Starquake disassembly
=====================
Published by Bubble Bus Software in 1985, Starquake was originally written by
Stephen Crow for the ZX Spectrum. It was converted to the BBC Micro in 1987 by
Kenton Price. It is a platform game in which the player must recover core
elements that are scattered around the depths of a 512 room planet.

The following disassembly was created by reverse engineering binary images,
without access to any source code. It is nevertheless reasonably complete,
allowing the technical approaches used to be understood.

The author of this disassembly imposes no additional copyright restrictions
beyond those already present on the game itself. It is provided for educational
purposes only, and it is hoped that the original authors will accept it in the
good faith it was intended - as a tribute to their skills.

Technical notes
===============
The custom tape loader is protected by a multi-stage routine written by Kenton
Price and Gary Partis, which uses EOR and VIA-based decryption. The disassembly
analyses each stage immediately after decryption has taken place.

Interesting pokes
=================
&1f13 = &00
player is invulnerable

&2db6 = &10
player can move through walls

&1304 = &00
infinite lives

&1cf0 = &00, &3153 = &00
infinite energy

&19a1 = &00
infinite fuel

&19c1 = &00
infinite ammunition

&2dbd = &60
no enemies

Tape protection disassembly
===========================
; QUAKE2
; 002600 002600 001000

; entry_point
&2600 a0 00    LDY #&00                                             # 151 successive EOR decryption loops
&2602 98       TYA
&2603 59 0c 26 EOR &260c,Y
&2606 99 0c 26 STA &260c,Y
&2609 c8       INY
&260a d0 f6    BNE &2602
&260c 98       TYA
&260d 59 16 26 EOR &2616,Y
&2610 99 16 26 STA &2616,Y
&2613 c8       INY
&2614 d0 f6    BNE &260c
&2616 98       TYA
&2617 49 c3    EOR #&c3
&2619 59 21 26 EOR &2621,Y
&261c 99 21 26 STA &2621,Y
&261f c8       INY
&2620 d0 f4    BNE &2616
&2622 b9 2c 26 LDA &262c,Y
&2625 49 ef    EOR #&ef
&2627 99 2c 26 STA &262c,Y
&262a c8       INY
&262b d0 f5    BNE &2622
&262d a9 4c    LDA #&4c
&262f 8d 87 02 STA &0287 ; BREAK intercept code
&2632 a9 02    LDA #&02
&2634 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2637 a9 87    LDA #&87
&2639 8d 88 02 STA &0288 ; BREAK intercept code + 1
&263c 98       TYA
&263d 49 9b    EOR #&9b
&263f 59 47 26 EOR &2647,Y
&2642 99 47 26 STA &2647,Y
&2645 c8       INY
&2646 d0 f4    BNE &263c
&2648 b9 53 26 LDA &2653,Y
&264b 49 a3    EOR #&a3
&264d 99 53 26 STA &2653,Y
&2650 c8       INY
&2651 d0 f5    BNE &2648
&2653 98       TYA
&2654 59 5d 26 EOR &265d,Y
&2657 99 5d 26 STA &265d,Y
&265a c8       INY
&265b d0 f6    BNE &2653
&265d 98       TYA
&265e 49 8d    EOR #&8d
&2660 59 68 26 EOR &2668,Y
&2663 99 68 26 STA &2668,Y
&2666 c8       INY
&2667 d0 f4    BNE &265d
&2669 98       TYA
&266a 59 73 26 EOR &2673,Y
&266d 99 73 26 STA &2673,Y
&2670 c8       INY
&2671 d0 f6    BNE &2669
&2673 b9 7e 26 LDA &267e,Y
&2676 49 8d    EOR #&8d
&2678 99 7e 26 STA &267e,Y
&267b c8       INY
&267c d0 f5    BNE &2673
&267e 98       TYA
&267f 59 88 26 EOR &2688,Y
&2682 99 88 26 STA &2688,Y
&2685 c8       INY
&2686 d0 f6    BNE &267e
&2688 98       TYA
&2689 59 92 26 EOR &2692,Y
&268c 99 92 26 STA &2692,Y
&268f c8       INY
&2690 d0 f6    BNE &2688
&2692 b9 9c 26 LDA &269c,Y
&2695 49 a0    EOR #&a0
&2697 99 9c 26 STA &269c,Y
&269a c8       INY
&269b d0 f5    BNE &2692
&269d a9 4c    LDA #&4c
&269f 8d 87 02 STA &0287 ; BREAK intercept code
&26a2 a9 02    LDA #&02
&26a4 8d 89 02 STA &0289 ; BREAK intercept code + 2
&26a7 a9 87    LDA #&87
&26a9 8d 88 02 STA &0288 ; BREAK intercept code + 1
&26ac 98       TYA
&26ad 59 b6 26 EOR &26b6,Y
&26b0 99 b6 26 STA &26b6,Y
&26b3 c8       INY
&26b4 d0 f6    BNE &26ac
&26b6 98       TYA
&26b7 59 c0 26 EOR &26c0,Y
&26ba 99 c0 26 STA &26c0,Y
&26bd c8       INY
&26be d0 f6    BNE &26b6
&26c0 98       TYA
&26c1 59 ca 26 EOR &26ca,Y
&26c4 99 ca 26 STA &26ca,Y
&26c7 c8       INY
&26c8 d0 f6    BNE &26c0
&26ca 98       TYA
&26cb 49 da    EOR #&da
&26cd 59 d5 26 EOR &26d5,Y
&26d0 99 d5 26 STA &26d5,Y
&26d3 c8       INY
&26d4 d0 f4    BNE &26ca
&26d6 b9 e0 26 LDA &26e0,Y
&26d9 49 9c    EOR #&9c
&26db 99 e0 26 STA &26e0,Y
&26de c8       INY
&26df d0 f5    BNE &26d6
&26e1 a9 4c    LDA #&4c
&26e3 8d 87 02 STA &0287 ; BREAK intercept code
&26e6 a9 02    LDA #&02
&26e8 8d 89 02 STA &0289 ; BREAK intercept code + 2
&26eb a9 87    LDA #&87
&26ed 8d 88 02 STA &0288 ; BREAK intercept code + 1
&26f0 b9 fa 26 LDA &26fa,Y
&26f3 49 f5    EOR #&f5
&26f5 99 fa 26 STA &26fa,Y
&26f8 c8       INY
&26f9 d0 f5    BNE &26f0
&26fb a9 4c    LDA #&4c
&26fd 8d 87 02 STA &0287 ; BREAK intercept code
&2700 a9 02    LDA #&02
&2702 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2705 a9 87    LDA #&87
&2707 8d 88 02 STA &0288 ; BREAK intercept code + 1
&270a 98       TYA
&270b 18       CLC
&270c 69 80    ADC #&80
&270e 49 c4    EOR #&c4
&2710 59 24 27 EOR &2724,Y
&2713 99 24 27 STA &2724,Y
&2716 c8       INY
&2717 d0 f1    BNE &270a
&2719 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&271b a2 03    LDX #&03 ; Clear memory on next RESET
&271d a0 00    LDY #&00
&271f 20 f4 ff JSR &fff4 ; OSBYTE
&2722 a0 00    LDY #&00
&2724 98       TYA
&2725 49 b5    EOR #&b5
&2727 59 2f 27 EOR &272f,Y
&272a 99 2f 27 STA &272f,Y
&272d c8       INY
&272e d0 f4    BNE &2724
&2730 b9 3b 27 LDA &273b,Y
&2733 49 da    EOR #&da
&2735 99 3b 27 STA &273b,Y
&2738 c8       INY
&2739 d0 f5    BNE &2730
&273b 98       TYA
&273c 59 45 27 EOR &2745,Y
&273f 99 45 27 STA &2745,Y
&2742 c8       INY
&2743 d0 f6    BNE &273b
&2745 98       TYA
&2746 49 86    EOR #&86
&2748 59 50 27 EOR &2750,Y
&274b 99 50 27 STA &2750,Y
&274e c8       INY
&274f d0 f4    BNE &2745
&2751 b9 5c 27 LDA &275c,Y
&2754 49 91    EOR #&91
&2756 99 5c 27 STA &275c,Y
&2759 c8       INY
&275a d0 f5    BNE &2751
&275c b9 66 27 LDA &2766,Y
&275f 49 bd    EOR #&bd
&2761 99 66 27 STA &2766,Y
&2764 c8       INY
&2765 d0 f5    BNE &275c
&2767 a9 4c    LDA #&4c
&2769 8d 87 02 STA &0287 ; BREAK intercept code
&276c a9 02    LDA #&02
&276e 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2771 a9 87    LDA #&87
&2773 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2776 98       TYA
&2777 49 d7    EOR #&d7
&2779 59 81 27 EOR &2781,Y
&277c 99 81 27 STA &2781,Y
&277f c8       INY
&2780 d0 f4    BNE &2776
&2782 98       TYA
&2783 49 98    EOR #&98
&2785 59 8d 27 EOR &278d,Y
&2788 99 8d 27 STA &278d,Y
&278b c8       INY
&278c d0 f4    BNE &2782
&278e 98       TYA
&278f 49 c0    EOR #&c0
&2791 59 99 27 EOR &2799,Y
&2794 99 99 27 STA &2799,Y
&2797 c8       INY
&2798 d0 f4    BNE &278e
&279a 98       TYA
&279b 49 c0    EOR #&c0
&279d 59 a5 27 EOR &27a5,Y
&27a0 99 a5 27 STA &27a5,Y
&27a3 c8       INY
&27a4 d0 f4    BNE &279a
&27a6 98       TYA
&27a7 59 b0 27 EOR &27b0,Y
&27aa 99 b0 27 STA &27b0,Y
&27ad c8       INY
&27ae d0 f6    BNE &27a6
&27b0 98       TYA
&27b1 59 ba 27 EOR &27ba,Y
&27b4 99 ba 27 STA &27ba,Y
&27b7 c8       INY
&27b8 d0 f6    BNE &27b0
&27ba 98       TYA
&27bb 59 c4 27 EOR &27c4,Y
&27be 99 c4 27 STA &27c4,Y
&27c1 c8       INY
&27c2 d0 f6    BNE &27ba
&27c4 98       TYA
&27c5 59 ce 27 EOR &27ce,Y
&27c8 99 ce 27 STA &27ce,Y
&27cb c8       INY
&27cc d0 f6    BNE &27c4
&27ce 98       TYA
&27cf 59 d8 27 EOR &27d8,Y
&27d2 99 d8 27 STA &27d8,Y
&27d5 c8       INY
&27d6 d0 f6    BNE &27ce
&27d8 b9 e2 27 LDA &27e2,Y
&27db 49 d3    EOR #&d3
&27dd 99 e2 27 STA &27e2,Y
&27e0 c8       INY
&27e1 d0 f5    BNE &27d8
&27e3 a9 4c    LDA #&4c
&27e5 8d 87 02 STA &0287 ; BREAK intercept code
&27e8 a9 02    LDA #&02
&27ea 8d 89 02 STA &0289 ; BREAK intercept code + 2
&27ed a9 87    LDA #&87
&27ef 8d 88 02 STA &0288 ; BREAK intercept code + 1
&27f2 98       TYA
&27f3 59 fc 27 EOR &27fc,Y
&27f6 99 fc 27 STA &27fc,Y
&27f9 c8       INY
&27fa d0 f6    BNE &27f2
&27fc 98       TYA
&27fd 18       CLC
&27fe 69 80    ADC #&80
&2800 49 87    EOR #&87
&2802 59 16 28 EOR &2816,Y
&2805 99 16 28 STA &2816,Y
&2808 c8       INY
&2809 d0 f1    BNE &27fc
&280b a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&280d a2 03    LDX #&03 ; Clear memory on next RESET
&280f a0 00    LDY #&00
&2811 20 f4 ff JSR &fff4 ; OSBYTE
&2814 a0 00    LDY #&00
&2816 98       TYA
&2817 59 20 28 EOR &2820,Y
&281a 99 20 28 STA &2820,Y
&281d c8       INY
&281e d0 f6    BNE &2816
&2820 98       TYA
&2821 18       CLC
&2822 69 80    ADC #&80
&2824 49 8c    EOR #&8c
&2826 59 3a 28 EOR &283a,Y
&2829 99 3a 28 STA &283a,Y
&282c c8       INY
&282d d0 f1    BNE &2820
&282f a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2831 a2 03    LDX #&03
&2833 a0 00    LDY #&00
&2835 20 f4 ff JSR &fff4 ; OSBYTE
&2838 a0 00    LDY #&00
&283a 98       TYA
&283b 59 44 28 EOR &2844,Y
&283e 99 44 28 STA &2844,Y
&2841 c8       INY
&2842 d0 f6    BNE &283a
&2844 b9 4f 28 LDA &284f,Y
&2847 49 e1    EOR #&e1
&2849 99 4f 28 STA &284f,Y
&284c c8       INY
&284d d0 f5    BNE &2844
&284f b9 59 28 LDA &2859,Y
&2852 49 af    EOR #&af
&2854 99 59 28 STA &2859,Y
&2857 c8       INY
&2858 d0 f5    BNE &284f
&285a a9 4c    LDA #&4c
&285c 8d 87 02 STA &0287 ; BREAK intercept code
&285f a9 02    LDA #&02
&2861 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2864 a9 87    LDA #&87
&2866 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2869 b9 73 28 LDA &2873,Y
&286c 49 e1    EOR #&e1
&286e 99 73 28 STA &2873,Y
&2871 c8       INY
&2872 d0 f5    BNE &2869
&2874 a9 4c    LDA #&4c
&2876 8d 87 02 STA &0287 ; BREAK intercept code
&2879 a9 02    LDA #&02
&287b 8d 89 02 STA &0289 ; BREAK intercept code + 2
&287e a9 87    LDA #&87
&2880 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2883 b9 8e 28 LDA &288e,Y
&2886 49 e6    EOR #&e6
&2888 99 8e 28 STA &288e,Y
&288b c8       INY
&288c d0 f5    BNE &2883
&288e 98       TYA
&288f 59 98 28 EOR &2898,Y
&2892 99 98 28 STA &2898,Y
&2895 c8       INY
&2896 d0 f6    BNE &288e
&2898 98       TYA
&2899 49 b5    EOR #&b5
&289b 59 a3 28 EOR &28a3,Y
&289e 99 a3 28 STA &28a3,Y
&28a1 c8       INY
&28a2 d0 f4    BNE &2898
&28a4 b9 ae 28 LDA &28ae,Y
&28a7 49 8a    EOR #&8a
&28a9 99 ae 28 STA &28ae,Y
&28ac c8       INY
&28ad d0 f5    BNE &28a4
&28af a9 4c    LDA #&4c
&28b1 8d 87 02 STA &0287 ; BREAK intercept code
&28b4 a9 02    LDA #&02
&28b6 8d 89 02 STA &0289 ; BREAK intercept code + 2
&28b9 a9 87    LDA #&87
&28bb 8d 88 02 STA &0288 ; BREAK intercept code + 1
&28be b9 c8 28 LDA &28c8,Y
&28c1 49 d0    EOR #&d0
&28c3 99 c8 28 STA &28c8,Y
&28c6 c8       INY
&28c7 d0 f5    BNE &28be
&28c9 a9 4c    LDA #&4c
&28cb 8d 87 02 STA &0287 ; BREAK intercept code
&28ce a9 02    LDA #&02
&28d0 8d 89 02 STA &0289 ; BREAK intercept code + 2
&28d3 a9 87    LDA #&87
&28d5 8d 88 02 STA &0288 ; BREAK intercept code + 1
&28d8 98       TYA
&28d9 59 e2 28 EOR &28e2,Y
&28dc 99 e2 28 STA &28e2,Y
&28df c8       INY
&28e0 d0 f6    BNE &28d8
&28e2 b9 ec 28 LDA &28ec,Y
&28e5 49 ba    EOR #&ba
&28e7 99 ec 28 STA &28ec,Y
&28ea c8       INY
&28eb d0 f5    BNE &28e2
&28ed a9 4c    LDA #&4c
&28ef 8d 87 02 STA &0287 ; BREAK intercept code
&28f2 a9 02    LDA #&02
&28f4 8d 89 02 STA &0289 ; BREAK intercept code + 2
&28f7 a9 87    LDA #&87
&28f9 8d 88 02 STA &0288 ; BREAK intercept code + 1
&28fc b9 06 29 LDA &2906,Y
&28ff 49 a1    EOR #&a1
&2901 99 06 29 STA &2906,Y
&2904 c8       INY
&2905 d0 f5    BNE &28fc
&2907 a9 4c    LDA #&4c
&2909 8d 87 02 STA &0287 ; BREAK intercept code
&290c a9 02    LDA #&02
&290e 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2911 a9 87    LDA #&87
&2913 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2916 98       TYA
&2917 18       CLC
&2918 69 80    ADC #&80
&291a 49 b9    EOR #&b9
&291c 59 30 29 EOR &2930,Y
&291f 99 30 29 STA &2930,Y
&2922 c8       INY
&2923 d0 f1    BNE &2916
&2925 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2927 a2 03    LDX #&03 ; Clear memory on next RESET
&2929 a0 00    LDY #&00
&292b 20 f4 ff JSR &fff4 ; OSBYTE
&292e a0 00    LDY #&00
&2930 98       TYA
&2931 18       CLC
&2932 69 80    ADC #&80
&2934 49 8b    EOR #&8b
&2936 59 4a 29 EOR &294a,Y
&2939 99 4a 29 STA &294a,Y
&293c c8       INY
&293d d0 f1    BNE &2930
&293f a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2941 a2 03    LDX #&03 ; Clear memory on next RESET
&2943 a0 00    LDY #&00
&2945 20 f4 ff JSR &fff4 ; OSBYTE
&2948 a0 00    LDY #&00
&294a b9 55 29 LDA &2955,Y
&294d 49 f1    EOR #&f1
&294f 99 55 29 STA &2955,Y
&2952 c8       INY
&2953 d0 f5    BNE &294a
&2955 98       TYA
&2956 49 f1    EOR #&f1
&2958 59 60 29 EOR &2960,Y
&295b 99 60 29 STA &2960,Y
&295e c8       INY
&295f d0 f4    BNE &2955
&2961 98       TYA
&2962 49 b3    EOR #&b3
&2964 59 6c 29 EOR &296c,Y
&2967 99 6c 29 STA &296c,Y
&296a c8       INY
&296b d0 f4    BNE &2961
&296d 98       TYA
&296e 18       CLC
&296f 69 80    ADC #&80
&2971 49 96    EOR #&96
&2973 59 87 29 EOR &2987,Y
&2976 99 87 29 STA &2987,Y
&2979 c8       INY
&297a d0 f1    BNE &296d
&297c a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&297e a2 03    LDX #&03 ; Clear memory on next RESET
&2980 a0 00    LDY #&00
&2982 20 f4 ff JSR &fff4 ; OSBYTE
&2985 a0 00    LDY #&00
&2987 b9 92 29 LDA &2992,Y
&298a 49 eb    EOR #&eb
&298c 99 92 29 STA &2992,Y
&298f c8       INY
&2990 d0 f5    BNE &2987
&2992 b9 9c 29 LDA &299c,Y
&2995 49 db    EOR #&db
&2997 99 9c 29 STA &299c,Y
&299a c8       INY
&299b d0 f5    BNE &2992
&299d a9 4c    LDA #&4c
&299f 8d 87 02 STA &0287 ; BREAK intercept code
&29a2 a9 02    LDA #&02
&29a4 8d 89 02 STA &0289 ; BREAK intercept code + 2
&29a7 a9 87    LDA #&87
&29a9 8d 88 02 STA &0288 ; BREAK intercept code + 1
&29ac 98       TYA
&29ad 49 a0    EOR #&a0
&29af 59 b7 29 EOR &29b7,Y
&29b2 99 b7 29 STA &29b7,Y
&29b5 c8       INY
&29b6 d0 f4    BNE &29ac
&29b8 98       TYA
&29b9 49 a1    EOR #&a1
&29bb 59 c3 29 EOR &29c3,Y
&29be 99 c3 29 STA &29c3,Y
&29c1 c8       INY
&29c2 d0 f4    BNE &29b8
&29c4 98       TYA
&29c5 18       CLC
&29c6 69 80    ADC #&80
&29c8 49 ef    EOR #&ef
&29ca 59 de 29 EOR &29de,Y
&29cd 99 de 29 STA &29de,Y
&29d0 c8       INY
&29d1 d0 f1    BNE &29c4
&29d3 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&29d5 a2 03    LDX #&03 ; Clear memory on next RESET
&29d7 a0 00    LDY #&00
&29d9 20 f4 ff JSR &fff4 ; OSBYTE
&29dc a0 00    LDY #&00
&29de b9 e8 29 LDA &29e8,Y
&29e1 49 c7    EOR #&c7
&29e3 99 e8 29 STA &29e8,Y
&29e6 c8       INY
&29e7 d0 f5    BNE &29de
&29e9 a9 4c    LDA #&4c
&29eb 8d 87 02 STA &0287 ; BREAK intercept code
&29ee a9 02    LDA #&02
&29f0 8d 89 02 STA &0289 ; BREAK intercept code + 2
&29f3 a9 87    LDA #&87
&29f5 8d 88 02 STA &0288 ; BREAK intercept code + 1
&29f8 98       TYA
&29f9 59 02 2a EOR &2a02,Y
&29fc 99 02 2a STA &2a02,Y
&29ff c8       INY
&2a00 d0 f6    BNE &29f8
&2a02 98       TYA
&2a03 59 0c 2a EOR &2a0c,Y
&2a06 99 0c 2a STA &2a0c,Y
&2a09 c8       INY
&2a0a d0 f6    BNE &2a02
&2a0c b9 16 2a LDA &2a16,Y
&2a0f 49 8b    EOR #&8b
&2a11 99 16 2a STA &2a16,Y
&2a14 c8       INY
&2a15 d0 f5    BNE &2a0c
&2a17 a9 4c    LDA #&4c
&2a19 8d 87 02 STA &0287 ; BREAK intercept code
&2a1c a9 02    LDA #&02
&2a1e 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2a21 a9 87    LDA #&87
&2a23 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2a26 98       TYA
&2a27 49 a1    EOR #&a1
&2a29 59 31 2a EOR &2a31,Y
&2a2c 99 31 2a STA &2a31,Y
&2a2f c8       INY
&2a30 d0 f4    BNE &2a26
&2a32 98       TYA
&2a33 59 3c 2a EOR &2a3c,Y
&2a36 99 3c 2a STA &2a3c,Y
&2a39 c8       INY
&2a3a d0 f6    BNE &2a32
&2a3c 98       TYA
&2a3d 59 46 2a EOR &2a46,Y
&2a40 99 46 2a STA &2a46,Y
&2a43 c8       INY
&2a44 d0 f6    BNE &2a3c
&2a46 98       TYA
&2a47 49 bd    EOR #&bd
&2a49 59 51 2a EOR &2a51,Y
&2a4c 99 51 2a STA &2a51,Y
&2a4f c8       INY
&2a50 d0 f4    BNE &2a46
&2a52 b9 5d 2a LDA &2a5d,Y
&2a55 49 f7    EOR #&f7
&2a57 99 5d 2a STA &2a5d,Y
&2a5a c8       INY
&2a5b d0 f5    BNE &2a52
&2a5d 98       TYA
&2a5e 59 67 2a EOR &2a67,Y
&2a61 99 67 2a STA &2a67,Y
&2a64 c8       INY
&2a65 d0 f6    BNE &2a5d
&2a67 98       TYA
&2a68 18       CLC
&2a69 69 80    ADC #&80
&2a6b 49 b3    EOR #&b3
&2a6d 59 81 2a EOR &2a81,Y
&2a70 99 81 2a STA &2a81,Y
&2a73 c8       INY
&2a74 d0 f1    BNE &2a67
&2a76 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2a78 a2 03    LDX #&03 ; Clear memory on next RESET
&2a7a a0 00    LDY #&00
&2a7c 20 f4 ff JSR &fff4 ; OSBYTE
&2a7f a0 00    LDY #&00
&2a81 98       TYA
&2a82 59 8b 2a EOR &2a8b,Y
&2a85 99 8b 2a STA &2a8b,Y
&2a88 c8       INY
&2a89 d0 f6    BNE &2a81
&2a8b 98       TYA
&2a8c 18       CLC
&2a8d 69 80    ADC #&80
&2a8f 49 de    EOR #&de
&2a91 59 a5 2a EOR &2aa5,Y
&2a94 99 a5 2a STA &2aa5,Y
&2a97 c8       INY
&2a98 d0 f1    BNE &2a8b
&2a9a a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2a9c a2 03    LDX #&03 ; Clear memory on next RESET
&2a9e a0 00    LDY #&00
&2aa0 20 f4 ff JSR &fff4 ; OSBYTE
&2aa3 a0 00    LDY #&00
&2aa5 b9 b0 2a LDA &2ab0,Y
&2aa8 49 d2    EOR #&d2
&2aaa 99 b0 2a STA &2ab0,Y
&2aad c8       INY
&2aae d0 f5    BNE &2aa5
&2ab0 98       TYA
&2ab1 18       CLC
&2ab2 69 80    ADC #&80
&2ab4 49 f0    EOR #&f0
&2ab6 59 ca 2a EOR &2aca,Y
&2ab9 99 ca 2a STA &2aca,Y
&2abc c8       INY
&2abd d0 f1    BNE &2ab0
&2abf a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2ac1 a2 03    LDX #&03 ; Clear memory on next RESET
&2ac3 a0 00    LDY #&00
&2ac5 20 f4 ff JSR &fff4 ; OSBYTE
&2ac8 a0 00    LDY #&00
&2aca b9 d5 2a LDA &2ad5,Y
&2acd 49 f6    EOR #&f6
&2acf 99 d5 2a STA &2ad5,Y
&2ad2 c8       INY
&2ad3 d0 f5    BNE &2aca
&2ad5 98       TYA
&2ad6 18       CLC
&2ad7 69 80    ADC #&80
&2ad9 49 ee    EOR #&ee
&2adb 59 ef 2a EOR &2aef,Y
&2ade 99 ef 2a STA &2aef,Y
&2ae1 c8       INY
&2ae2 d0 f1    BNE &2ad5
&2ae4 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2ae6 a2 03    LDX #&03 ; Clear memory on next RESET
&2ae8 a0 00    LDY #&00
&2aea 20 f4 ff JSR &fff4 ; OSBYTE
&2aed a0 00    LDY #&00
&2aef 98       TYA
&2af0 59 f9 2a EOR &2af9,Y
&2af3 99 f9 2a STA &2af9,Y
&2af6 c8       INY
&2af7 d0 f6    BNE &2aef
&2af9 98       TYA
&2afa 59 03 2b EOR &2b03,Y
&2afd 99 03 2b STA &2b03,Y
&2b00 c8       INY
&2b01 d0 f6    BNE &2af9
&2b03 98       TYA
&2b04 49 f5    EOR #&f5
&2b06 59 0e 2b EOR &2b0e,Y
&2b09 99 0e 2b STA &2b0e,Y
&2b0c c8       INY
&2b0d d0 f4    BNE &2b03
&2b0f 98       TYA
&2b10 18       CLC
&2b11 69 80    ADC #&80
&2b13 49 fd    EOR #&fd
&2b15 59 29 2b EOR &2b29,Y
&2b18 99 29 2b STA &2b29,Y
&2b1b c8       INY
&2b1c d0 f1    BNE &2b0f
&2b1e a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2b20 a2 03    LDX #&03 ; Clear memory on next RESET
&2b22 a0 00    LDY #&00
&2b24 20 f4 ff JSR &fff4 ; OSBYTE
&2b27 a0 00    LDY #&00
&2b29 b9 34 2b LDA &2b34,Y
&2b2c 49 93    EOR #&93
&2b2e 99 34 2b STA &2b34,Y
&2b31 c8       INY
&2b32 d0 f5    BNE &2b29
&2b34 98       TYA
&2b35 18       CLC
&2b36 69 80    ADC #&80
&2b38 49 d9    EOR #&d9
&2b3a 59 4e 2b EOR &2b4e,Y
&2b3d 99 4e 2b STA &2b4e,Y
&2b40 c8       INY
&2b41 d0 f1    BNE &2b34
&2b43 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2b45 a2 03    LDX #&03 ; Clear memory on next RESET
&2b47 a0 00    LDY #&00
&2b49 20 f4 ff JSR &fff4 ; OSBYTE
&2b4c a0 00    LDY #&00
&2b4e b9 58 2b LDA &2b58,Y
&2b51 49 80    EOR #&80
&2b53 99 58 2b STA &2b58,Y
&2b56 c8       INY
&2b57 d0 f5    BNE &2b4e
&2b59 a9 4c    LDA #&4c
&2b5b 8d 87 02 STA &0287 ; BREAK intercept code
&2b5e a9 02    LDA #&02
&2b60 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2b63 a9 87    LDA #&87
&2b65 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2b68 98       TYA
&2b69 49 d0    EOR #&d0
&2b6b 59 73 2b EOR &2b73,Y
&2b6e 99 73 2b STA &2b73,Y
&2b71 c8       INY
&2b72 d0 f4    BNE &2b68
&2b74 98       TYA
&2b75 49 f2    EOR #&f2
&2b77 59 7f 2b EOR &2b7f,Y
&2b7a 99 7f 2b STA &2b7f,Y
&2b7d c8       INY
&2b7e d0 f4    BNE &2b74
&2b80 98       TYA
&2b81 49 9c    EOR #&9c
&2b83 59 8b 2b EOR &2b8b,Y
&2b86 99 8b 2b STA &2b8b,Y
&2b89 c8       INY
&2b8a d0 f4    BNE &2b80
&2b8c b9 97 2b LDA &2b97,Y
&2b8f 49 ab    EOR #&ab
&2b91 99 97 2b STA &2b97,Y
&2b94 c8       INY
&2b95 d0 f5    BNE &2b8c
&2b97 98       TYA
&2b98 59 a1 2b EOR &2ba1,Y
&2b9b 99 a1 2b STA &2ba1,Y
&2b9e c8       INY
&2b9f d0 f6    BNE &2b97
&2ba1 b9 ab 2b LDA &2bab,Y
&2ba4 49 ee    EOR #&ee
&2ba6 99 ab 2b STA &2bab,Y
&2ba9 c8       INY
&2baa d0 f5    BNE &2ba1
&2bac a9 4c    LDA #&4c
&2bae 8d 87 02 STA &0287 ; BREAK intercept code
&2bb1 a9 02    LDA #&02
&2bb3 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2bb6 a9 87    LDA #&87
&2bb8 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2bbb b9 c6 2b LDA &2bc6,Y
&2bbe 49 93    EOR #&93
&2bc0 99 c6 2b STA &2bc6,Y
&2bc3 c8       INY
&2bc4 d0 f5    BNE &2bbb
&2bc6 98       TYA
&2bc7 49 b1    EOR #&b1
&2bc9 59 d1 2b EOR &2bd1,Y
&2bcc 99 d1 2b STA &2bd1,Y
&2bcf c8       INY
&2bd0 d0 f4    BNE &2bc6
&2bd2 98       TYA
&2bd3 59 dc 2b EOR &2bdc,Y
&2bd6 99 dc 2b STA &2bdc,Y
&2bd9 c8       INY
&2bda d0 f6    BNE &2bd2
&2bdc 98       TYA
&2bdd 49 95    EOR #&95
&2bdf 59 e7 2b EOR &2be7,Y
&2be2 99 e7 2b STA &2be7,Y
&2be5 c8       INY
&2be6 d0 f4    BNE &2bdc
&2be8 98       TYA
&2be9 18       CLC
&2bea 69 80    ADC #&80
&2bec 49 c2    EOR #&c2
&2bee 59 02 2c EOR &2c02,Y
&2bf1 99 02 2c STA &2c02,Y
&2bf4 c8       INY
&2bf5 d0 f1    BNE &2be8
&2bf7 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2bf9 a2 03    LDX #&03 ; Clear memory on next RESET
&2bfb a0 00    LDY #&00
&2bfd 20 f4 ff JSR &fff4 ; OSBYTE
&2c00 a0 00    LDY #&00
&2c02 b9 0d 2c LDA &2c0d,Y
&2c05 49 96    EOR #&96
&2c07 99 0d 2c STA &2c0d,Y
&2c0a c8       INY
&2c0b d0 f5    BNE &2c02
&2c0d b9 18 2c LDA &2c18,Y
&2c10 49 e5    EOR #&e5
&2c12 99 18 2c STA &2c18,Y
&2c15 c8       INY
&2c16 d0 f5    BNE &2c0d
&2c18 98       TYA
&2c19 49 8b    EOR #&8b
&2c1b 59 23 2c EOR &2c23,Y
&2c1e 99 23 2c STA &2c23,Y
&2c21 c8       INY
&2c22 d0 f4    BNE &2c18
&2c24 98       TYA
&2c25 59 2e 2c EOR &2c2e,Y
&2c28 99 2e 2c STA &2c2e,Y
&2c2b c8       INY
&2c2c d0 f6    BNE &2c24
&2c2e 98       TYA
&2c2f 49 da    EOR #&da
&2c31 59 39 2c EOR &2c39,Y
&2c34 99 39 2c STA &2c39,Y
&2c37 c8       INY
&2c38 d0 f4    BNE &2c2e
&2c3a b9 45 2c LDA &2c45,Y
&2c3d 49 c0    EOR #&c0
&2c3f 99 45 2c STA &2c45,Y
&2c42 c8       INY
&2c43 d0 f5    BNE &2c3a
&2c45 98       TYA
&2c46 59 4f 2c EOR &2c4f,Y
&2c49 99 4f 2c STA &2c4f,Y
&2c4c c8       INY
&2c4d d0 f6    BNE &2c45
&2c4f 98       TYA
&2c50 18       CLC
&2c51 69 80    ADC #&80
&2c53 49 ec    EOR #&ec
&2c55 59 69 2c EOR &2c69,Y
&2c58 99 69 2c STA &2c69,Y
&2c5b c8       INY
&2c5c d0 f1    BNE &2c4f
&2c5e a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2c60 a2 03    LDX #&03 ; Clear memory on next RESET
&2c62 a0 00    LDY #&00
&2c64 20 f4 ff JSR &fff4 ; OSBYTE
&2c67 a0 00    LDY #&00
&2c69 b9 73 2c LDA &2c73,Y
&2c6c 49 b3    EOR #&b3
&2c6e 99 73 2c STA &2c73,Y
&2c71 c8       INY
&2c72 d0 f5    BNE &2c69
&2c74 a9 4c    LDA #&4c
&2c76 8d 87 02 STA &0287 ; BREAK intercept code
&2c79 a9 02    LDA #&02
&2c7b 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2c7e a9 87    LDA #&87
&2c80 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2c83 98       TYA
&2c84 49 c0    EOR #&c0
&2c86 59 8e 2c EOR &2c8e,Y
&2c89 99 8e 2c STA &2c8e,Y
&2c8c c8       INY
&2c8d d0 f4    BNE &2c83
&2c8f b9 99 2c LDA &2c99,Y
&2c92 49 ac    EOR #&ac
&2c94 99 99 2c STA &2c99,Y
&2c97 c8       INY
&2c98 d0 f5    BNE &2c8f
&2c9a a9 4c    LDA #&4c
&2c9c 8d 87 02 STA &0287 ; BREAK intercept code
&2c9f a9 02    LDA #&02
&2ca1 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2ca4 a9 87    LDA #&87
&2ca6 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2ca9 b9 b3 2c LDA &2cb3,Y
&2cac 49 ce    EOR #&ce
&2cae 99 b3 2c STA &2cb3,Y
&2cb1 c8       INY
&2cb2 d0 f5    BNE &2ca9
&2cb4 a9 4c    LDA #&4c
&2cb6 8d 87 02 STA &0287 ; BREAK intercept code
&2cb9 a9 02    LDA #&02
&2cbb 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2cbe a9 87    LDA #&87
&2cc0 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2cc3 b9 cd 2c LDA &2ccd,Y
&2cc6 49 db    EOR #&db
&2cc8 99 cd 2c STA &2ccd,Y
&2ccb c8       INY
&2ccc d0 f5    BNE &2cc3
&2cce a9 4c    LDA #&4c
&2cd0 8d 87 02 STA &0287 ; BREAK intercept code
&2cd3 a9 02    LDA #&02
&2cd5 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2cd8 a9 87    LDA #&87
&2cda 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2cdd b9 e8 2c LDA &2ce8,Y
&2ce0 49 ea    EOR #&ea
&2ce2 99 e8 2c STA &2ce8,Y
&2ce5 c8       INY
&2ce6 d0 f5    BNE &2cdd
&2ce8 98       TYA
&2ce9 49 80    EOR #&80
&2ceb 59 f3 2c EOR &2cf3,Y
&2cee 99 f3 2c STA &2cf3,Y
&2cf1 c8       INY
&2cf2 d0 f4    BNE &2ce8
&2cf4 b9 fe 2c LDA &2cfe,Y
&2cf7 49 b9    EOR #&b9
&2cf9 99 fe 2c STA &2cfe,Y
&2cfc c8       INY
&2cfd d0 f5    BNE &2cf4
&2cff a9 4c    LDA #&4c
&2d01 8d 87 02 STA &0287 ; BREAK intercept code
&2d04 a9 02    LDA #&02
&2d06 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2d09 a9 87    LDA #&87
&2d0b 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2d0e b9 18 2d LDA &2d18,Y
&2d11 49 c0    EOR #&c0
&2d13 99 18 2d STA &2d18,Y
&2d16 c8       INY
&2d17 d0 f5    BNE &2d0e
&2d19 a9 4c    LDA #&4c
&2d1b 8d 87 02 STA &0287 ; BREAK intercept code
&2d1e a9 02    LDA #&02
&2d20 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2d23 a9 87    LDA #&87
&2d25 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2d28 98       TYA
&2d29 18       CLC
&2d2a 69 80    ADC #&80
&2d2c 49 c4    EOR #&c4
&2d2e 59 42 2d EOR &2d42,Y
&2d31 99 42 2d STA &2d42,Y
&2d34 c8       INY
&2d35 d0 f1    BNE &2d28
&2d37 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2d39 a2 03    LDX #&03 ; Clear memory on next RESET
&2d3b a0 00    LDY #&00
&2d3d 20 f4 ff JSR &fff4 ; OSBYTE
&2d40 a0 00    LDY #&00
&2d42 b9 4d 2d LDA &2d4d,Y
&2d45 49 e8    EOR #&e8
&2d47 99 4d 2d STA &2d4d,Y
&2d4a c8       INY
&2d4b d0 f5    BNE &2d42
&2d4d 98       TYA
&2d4e 49 d1    EOR #&d1
&2d50 59 58 2d EOR &2d58,Y
&2d53 99 58 2d STA &2d58,Y
&2d56 c8       INY
&2d57 d0 f4    BNE &2d4d
&2d59 b9 63 2d LDA &2d63,Y
&2d5c 49 cf    EOR #&cf
&2d5e 99 63 2d STA &2d63,Y
&2d61 c8       INY
&2d62 d0 f5    BNE &2d59
&2d64 a9 4c    LDA #&4c
&2d66 8d 87 02 STA &0287 ; BREAK intercept code
&2d69 a9 02    LDA #&02
&2d6b 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2d6e a9 87    LDA #&87
&2d70 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2d73 b9 7e 2d LDA &2d7e,Y
&2d76 49 e5    EOR #&e5
&2d78 99 7e 2d STA &2d7e,Y
&2d7b c8       INY
&2d7c d0 f5    BNE &2d73
&2d7e 98       TYA
&2d7f 59 88 2d EOR &2d88,Y
&2d82 99 88 2d STA &2d88,Y
&2d85 c8       INY
&2d86 d0 f6    BNE &2d7e
&2d88 b9 92 2d LDA &2d92,Y
&2d8b 49 80    EOR #&80
&2d8d 99 92 2d STA &2d92,Y
&2d90 c8       INY
&2d91 d0 f5    BNE &2d88
&2d93 a9 4c    LDA #&4c
&2d95 8d 87 02 STA &0287 ; BREAK intercept code
&2d98 a9 02    LDA #&02
&2d9a 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2d9d a9 87    LDA #&87
&2d9f 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2da2 b9 ac 2d LDA &2dac,Y
&2da5 49 c6    EOR #&c6
&2da7 99 ac 2d STA &2dac,Y
&2daa c8       INY
&2dab d0 f5    BNE &2da2
&2dad a9 4c    LDA #&4c
&2daf 8d 87 02 STA &0287 ; BREAK intercept code
&2db2 a9 02    LDA #&02
&2db4 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2db7 a9 87    LDA #&87
&2db9 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2dbc 98       TYA
&2dbd 59 c6 2d EOR &2dc6,Y
&2dc0 99 c6 2d STA &2dc6,Y
&2dc3 c8       INY
&2dc4 d0 f6    BNE &2dbc
&2dc6 98       TYA
&2dc7 59 d0 2d EOR &2dd0,Y
&2dca 99 d0 2d STA &2dd0,Y
&2dcd c8       INY
&2dce d0 f6    BNE &2dc6
&2dd0 98       TYA
&2dd1 49 82    EOR #&82
&2dd3 59 db 2d EOR &2ddb,Y
&2dd6 99 db 2d STA &2ddb,Y
&2dd9 c8       INY
&2dda d0 f4    BNE &2dd0
&2ddc 98       TYA
&2ddd 18       CLC
&2dde 69 80    ADC #&80
&2de0 49 a0    EOR #&a0
&2de2 59 f6 2d EOR &2df6,Y
&2de5 99 f6 2d STA &2df6,Y
&2de8 c8       INY
&2de9 d0 f1    BNE &2ddc
&2deb a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2ded a2 03    LDX #&03 ; Clear memory on next RESET
&2def a0 00    LDY #&00
&2df1 20 f4 ff JSR &fff4 ; OSBYTE
&2df4 a0 00    LDY #&00
&2df6 98       TYA
&2df7 59 00 2e EOR &2e00,Y
&2dfa 99 00 2e STA &2e00,Y
&2dfd c8       INY
&2dfe d0 f6    BNE &2df6
&2e00 b9 0b 2e LDA &2e0b,Y
&2e03 49 9d    EOR #&9d
&2e05 99 0b 2e STA &2e0b,Y
&2e08 c8       INY
&2e09 d0 f5    BNE &2e00
&2e0b b9 16 2e LDA &2e16,Y
&2e0e 49 db    EOR #&db
&2e10 99 16 2e STA &2e16,Y
&2e13 c8       INY
&2e14 d0 f5    BNE &2e0b
&2e16 b9 21 2e LDA &2e21,Y
&2e19 49 99    EOR #&99
&2e1b 99 21 2e STA &2e21,Y
&2e1e c8       INY
&2e1f d0 f5    BNE &2e16
&2e21 98       TYA
&2e22 59 2b 2e EOR &2e2b,Y
&2e25 99 2b 2e STA &2e2b,Y
&2e28 c8       INY
&2e29 d0 f6    BNE &2e21
&2e2b 98       TYA
&2e2c 18       CLC
&2e2d 69 80    ADC #&80
&2e2f 49 e5    EOR #&e5
&2e31 59 45 2e EOR &2e45,Y
&2e34 99 45 2e STA &2e45,Y
&2e37 c8       INY
&2e38 d0 f1    BNE &2e2b
&2e3a a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2e3c a2 03    LDX #&03 ; Clear memory on next RESET
&2e3e a0 00    LDY #&00
&2e40 20 f4 ff JSR &fff4 ; OSBYTE
&2e43 a0 00    LDY #&00
&2e45 98       TYA
&2e46 49 b2    EOR #&b2
&2e48 59 50 2e EOR &2e50,Y
&2e4b 99 50 2e STA &2e50,Y
&2e4e c8       INY
&2e4f d0 f4    BNE &2e45
&2e51 98       TYA
&2e52 49 b2    EOR #&b2
&2e54 59 5c 2e EOR &2e5c,Y
&2e57 99 5c 2e STA &2e5c,Y
&2e5a c8       INY
&2e5b d0 f4    BNE &2e51
&2e5d b9 68 2e LDA &2e68,Y
&2e60 49 9e    EOR #&9e
&2e62 99 68 2e STA &2e68,Y
&2e65 c8       INY
&2e66 d0 f5    BNE &2e5d
&2e68 98       TYA
&2e69 59 72 2e EOR &2e72,Y
&2e6c 99 72 2e STA &2e72,Y
&2e6f c8       INY
&2e70 d0 f6    BNE &2e68
&2e72 98       TYA
&2e73 49 b5    EOR #&b5
&2e75 59 7d 2e EOR &2e7d,Y
&2e78 99 7d 2e STA &2e7d,Y
&2e7b c8       INY
&2e7c d0 f4    BNE &2e72
&2e7e b9 89 2e LDA &2e89,Y
&2e81 49 a3    EOR #&a3
&2e83 99 89 2e STA &2e89,Y
&2e86 c8       INY
&2e87 d0 f5    BNE &2e7e
&2e89 98       TYA
&2e8a 49 d6    EOR #&d6
&2e8c 59 94 2e EOR &2e94,Y
&2e8f 99 94 2e STA &2e94,Y
&2e92 c8       INY
&2e93 d0 f4    BNE &2e89
&2e95 98       TYA
&2e96 49 9b    EOR #&9b
&2e98 59 a0 2e EOR &2ea0,Y
&2e9b 99 a0 2e STA &2ea0,Y
&2e9e c8       INY
&2e9f d0 f4    BNE &2e95
&2ea1 98       TYA
&2ea2 18       CLC
&2ea3 69 80    ADC #&80
&2ea5 49 ac    EOR #&ac
&2ea7 59 bb 2e EOR &2ebb,Y
&2eaa 99 bb 2e STA &2ebb,Y
&2ead c8       INY
&2eae d0 f1    BNE &2ea1
&2eb0 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2eb2 a2 03    LDX #&03 ; Clear memory on next RESET
&2eb4 a0 00    LDY #&00
&2eb6 20 f4 ff JSR &fff4 ; OSBYTE
&2eb9 a0 00    LDY #&00
&2ebb 98       TYA
&2ebc 18       CLC
&2ebd 69 80    ADC #&80
&2ebf 49 88    EOR #&88
&2ec1 59 d5 2e EOR &2ed5,Y
&2ec4 99 d5 2e STA &2ed5,Y
&2ec7 c8       INY
&2ec8 d0 f1    BNE &2ebb
&2eca a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2ecc a2 03    LDX #&03 ; Clear memory on next RESET
&2ece a0 00    LDY #&00
&2ed0 20 f4 ff JSR &fff4 ; OSBYTE
&2ed3 a0 00    LDY #&00
&2ed5 b9 df 2e LDA &2edf,Y
&2ed8 49 b0    EOR #&b0
&2eda 99 df 2e STA &2edf,Y
&2edd c8       INY
&2ede d0 f5    BNE &2ed5
&2ee0 a9 4c    LDA #&4c
&2ee2 8d 87 02 STA &0287 ; BREAK intercept code
&2ee5 a9 02    LDA #&02
&2ee7 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2eea a9 87    LDA #&87
&2eec 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2eef b9 fa 2e LDA &2efa,Y
&2ef2 49 92    EOR #&92
&2ef4 99 fa 2e STA &2efa,Y
&2ef7 c8       INY
&2ef8 d0 f5    BNE &2eef
&2efa 98       TYA
&2efb 59 04 2f EOR &2f04,Y
&2efe 99 04 2f STA &2f04,Y
&2f01 c8       INY
&2f02 d0 f6    BNE &2efa
&2f04 98       TYA
&2f05 49 99    EOR #&99
&2f07 59 0f 2f EOR &2f0f,Y
&2f0a 99 0f 2f STA &2f0f,Y
&2f0d c8       INY
&2f0e d0 f4    BNE &2f04
&2f10 b9 1a 2f LDA &2f1a,Y
&2f13 49 b1    EOR #&b1
&2f15 99 1a 2f STA &2f1a,Y
&2f18 c8       INY
&2f19 d0 f5    BNE &2f10
&2f1b a9 4c    LDA #&4c
&2f1d 8d 87 02 STA &0287 ; BREAK intercept code
&2f20 a9 02    LDA #&02
&2f22 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2f25 a9 87    LDA #&87
&2f27 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2f2a 98       TYA
&2f2b 49 d9    EOR #&d9
&2f2d 59 35 2f EOR &2f35,Y
&2f30 99 35 2f STA &2f35,Y
&2f33 c8       INY
&2f34 d0 f4    BNE &2f2a
&2f36 b9 40 2f LDA &2f40,Y
&2f39 49 b3    EOR #&b3
&2f3b 99 40 2f STA &2f40,Y
&2f3e c8       INY
&2f3f d0 f5    BNE &2f36
&2f41 a9 4c    LDA #&4c
&2f43 8d 87 02 STA &0287 ; BREAK intercept code
&2f46 a9 02    LDA #&02
&2f48 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2f4b a9 87    LDA #&87
&2f4d 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2f50 98       TYA
&2f51 18       CLC
&2f52 69 80    ADC #&80
&2f54 49 c8    EOR #&c8
&2f56 59 6a 2f EOR &2f6a,Y
&2f59 99 6a 2f STA &2f6a,Y
&2f5c c8       INY
&2f5d d0 f1    BNE &2f50
&2f5f a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2f61 a2 03    LDX #&03 ; Clear memory on next RESET
&2f63 a0 00    LDY #&00
&2f65 20 f4 ff JSR &fff4 ; OSBYTE
&2f68 a0 00    LDY #&00
&2f6a 4c bd 2f JMP &2fbd ; decrypt_via_decryption
; unused                                                            # &2f6d - &2fbc is never executed
&2f6d 49 dd    EOR #&dd
&2f6f 99 74 2f STA &2f74,Y
&2f72 c8       INY
&2f73 d0 28    BNE &2f9d
&2f75 a9 4c    LDA #&4c
&2f77 8d 87 02 STA &0287 ; BREAK intercept code
&2f7a a9 02    LDA #&02
&2f7c 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2f7f a9 87    LDA #&87
&2f81 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2f84 b9 8e 2f LDA &2f8e,Y
&2f87 49 d6    EOR #&d6
&2f89 99 8e 2f STA &2f8e,Y
&2f8c c8       INY
&2f8d d0 23    BNE &2fb2
&2f8f a9 4c    LDA #&4c
&2f91 8d 87 02 STA &0287 ; BREAK intercept code
&2f94 a9 02    LDA #&02
&2f96 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2f99 a9 87    LDA #&87
&2f9b 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2f9e 98       TYA
&2f9f 49 99    EOR #&99
&2fa1 59 a9 2f EOR &2fa9,Y
&2fa4 99 a9 2f STA &2fa9,Y
&2fa7 c8       INY
&2fa8 d0 6d    BNE &3017
&2faa 98       TYA
&2fab 18       CLC
&2fac 69 80    ADC #&80
&2fae 49 e9    EOR #&e9
&2fb0 59 c4 2f EOR &2fc4,Y
&2fb3 99 c4 2f STA &2fc4,Y
&2fb6 c8       INY
&2fb7 d0 f1    BNE &2faa
&2fb9 a9 c8    LDA #&c8
&2fbb a2 03    LDX #&03
; decrypt_via_decryption
&2fbd a0 00    LDY #&00                                             # Decrypt main decryption routine
&2fbf 84 8e    STY &8e ; address_low
&2fc1 a9 30    LDA #&30 ; &3000 = via_decryption
&2fc3 85 8f    STA &8f ; address_high
&2fc5 84 8d    STY &8d ; eor
&2fc7 a2 06    LDX #&06
; decrypt_via_decryption_loop                                       # Decrypt &3000 - &35ff
&2fc9 98       TYA
&2fca 51 8e    EOR (&8e),Y ; address
&2fcc 49 ad    EOR #&ad
&2fce 91 8e    STA (&8e),Y ; address
&2fd0 45 8d    EOR &8d ; eor
&2fd2 85 8d    STA &8d ; eor
&2fd4 c8       INY
&2fd5 d0 f2    BNE &2fc9 ; decrypt_via_decryption_loop
&2fd7 e6 8f    INC &8f ; address_high
&2fd9 ca       DEX
&2fda d0 ed    BNE &2fc9 ; decrypt_via_decryption_loop
&2fdc 78       SEI
&2fdd a9 4c    LDA #&4c
&2fdf 8d 87 02 STA &0287 ; BREAK intercept code
&2fe2 a9 02    LDA #&02
&2fe4 8d 89 02 STA &0289 ; BREAK intercept code + 2
&2fe7 a9 87    LDA #&87
&2fe9 8d 88 02 STA &0288 ; BREAK intercept code + 1
&2fec a5 8d    LDA &8d ; eor
&2fee c9 62    CMP #&62
&2ff0 f0 03    BEQ &2ff5 ; skip_reset                               # Reset system if decrypted data not as expected
&2ff2 6c fc ff JMP (&fffc) ; os_reset_address
; skip_reset
&2ff5 a0 00    LDY #&00
; copy_0800_loop
&2ff7 b9 00 08 LDA &0800,Y                                          # Copy &0800 - &08ff to &1100 - &11ff
&2ffa 99 00 11 STA &1100,Y                                          # (OS sound workspace, buffers and envelopes)
&2ffd c8       INY
&2ffe d0 f7    BNE &2ff7 ; copy_0800_loop
; via_decryption
&3000 a9 0f    LDA #&0f ; Flush all buffers
&3002 a2 00    LDX #&00
&3004 20 f4 ff JSR &fff4 ; OSBYTE
&3007 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&3009 a2 03    LDX #&03 ; Clear memory on next RESET
&300b a0 00    LDY #&00
&300d 20 f4 ff JSR &fff4 ; OSBYTE
&3010 78       SEI
&3011 a9 df    LDA #&df                                             # Set User VIA timer 2 to timed interrupt
&3013 2d 6b fe AND &fe6b ; User VIA auxiliary control register
&3016 8d 6b fe STA &fe6b ; User VIA auxiliary control register
&3019 a9 a0    LDA #&a0                                             # Enable interrupts for User VIA timer 2
&301b 8d 6e fe STA &fe6e ; User VIA interrupt enable register
&301e a9 00    LDA #&00
&3020 8d 68 fe STA &fe68 ; User VIA timer 2 counter LSB
&3023 8d 69 fe STA &fe69 ; User VIA timer 2 counter MSB
&3026 38       SEC
&3027 a2 00    LDX #&00                                             # 256 rounds
&3029 a0 00    LDY #&00
; via_decryption_loop
&302b b9 00 31 LDA &3100,Y ; payload
&302e 59 41 32 EOR &3241,Y                                          # Runs over &3241 - &3340
&3031 4d 00 34 EOR &3400
#     actually EOR &3400 + via_decryption_offset_one                # Runs over &3400 - &34ff
&3034 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&3037 5d 01 32 EOR &3201,X                                          # Runs over &3201 - &3300
&303a 48       PHA
&303b a9 7f    LDA #&7f                                             # Disable all system interrupts
&303d 8d 4e fe STA &fe4e ; System VIA interrupt enable register
&3040 68       PLA
&3041 5d 46 32 EOR &3246,X                                          # Runs over &3246 - &3345
&3044 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&3047 4d 24 33 EOR &3324
#     actually EOR &3300 + via_decryption_offset_two                # Runs over &3300 - &33ff, starting at &3324
&304a 5d f2 33 EOR &33f2,X                                          # Runs over &33f2 - &34f1
&304d 59 01 32 EOR &3201,Y                                          # Runs over &3201 - &3300
&3050 49 38    EOR #&38
&3052 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&3055 5d 24 33 EOR &3324,X                                          # Runs over &3324 - &3423
&3058 4d 83 33 EOR &3383
#     actually EOR &3300 + via_decryption_offset_three              # Runs over &3300 - &33ff, starting at &3383
&305b 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&305e 5d 01 33 EOR &3301,X                                          # Runs over &3301 - &3400
&3061 59 84 33 EOR &3384,Y                                          # Runs over &3384 - &3483
&3064 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&3067 4d ff 33 EOR &33ff
#     actually EOR &3300 + via_decryption_offset_four               # Runs over &3300 - &33ff, starting at &33ff
&306a 59 81 32 EOR &3281,Y                                          # Runs over &3281 - &3380
&306d 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&3070 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&3073 4d 77 32 EOR &3277
#     actually EOR &3200 + via_decryption_offset_five               # Runs over &3200 - &32ff, starting at &3277
&3076 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&3079 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&307c 4d 5a 33 EOR &335a
#     actually EOR &3300 + via_decryption_offset_six                # Runs over &3300 - &33ff, starting at &335a
&307f 59 33 33 EOR &3333,Y                                          # Runs over &3333 - &3432
&3082 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&3085 5d 71 33 EOR &3371,X                                          # Runs over &3371 - &3470
&3088 5d 01 32 EOR &3201,X                                          # Runs over &3201 - &3300
&308b 59 01 32 EOR &3201,Y                                          # Runs over &3201 - &3300
&308e 99 00 31 STA &3100,Y ; payload
&3091 ad 68 30 LDA &3068 ; via_decryption_offset_four
&3094 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&3097 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&309a 8d 68 30 STA &3068 ; via_decryption_offset_four
&309d 4d 7d 30 EOR &307d ; via_decryption_offset_six
&30a0 49 38    EOR #&38
&30a2 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&30a5 8d 7d 30 STA &307d ; via_decryption_offset_six
&30a8 4d 48 30 EOR &3048 ; via_decryption_offset_two
&30ab 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&30ae 4d 68 30 EOR &3068 ; via_decryption_offset_four
&30b1 4d 74 30 EOR &3074 ; via_decryption_offset_five
&30b4 8d 48 30 STA &3048 ; via_decryption_offset_two
&30b7 4d 32 30 EOR &3032 ; via_decryption_offset_one
&30ba 4d 48 30 EOR &3048 ; via_decryption_offset_two
&30bd 8d 32 30 STA &3032 ; via_decryption_offset_one
&30c0 4d 74 30 EOR &3074 ; via_decryption_offset_five
&30c3 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&30c6 e9 c8    SBC #&c8
&30c8 4d 32 30 EOR &3032 ; via_decryption_offset_one
&30cb 8d 74 30 STA &3074 ; via_decryption_offset_five
&30ce 4d 48 30 EOR &3048 ; via_decryption_offset_two
&30d1 4d 59 30 EOR &3059 ; via_decryption_offset_three
&30d4 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&30d7 8d 59 30 STA &3059 ; via_decryption_offset_three
&30da c8       INY
&30db f0 03    BEQ &30e0 ; next_round
&30dd 4c 2b 30 JMP &302b ; via_decryption_loop
; next_round                                                        # Run over every byte of payload 256 times
&30e0 e8       INX
&30e1 f0 03    BEQ &30e6 ; finished_decryption
&30e3 4c 2b 30 JMP &302b ; via_decryption_loop
; finished_decryption
&30e6 a9 20    LDA #&20                                             # Disable interrupts for User VIA timer 2
&30e8 8d 6e fe STA &fe6e ; User VIA interrupt enable register
&30eb a2 00    LDX #&00
&30ed 8a       TXA
; wipe_3000_to_30ea_loop                                            # Wipe &3000 - &30ea (via_decryption)
&30ee 9d 00 30 STA &3000,X ; via_decryption
&30f1 e8       INX
&30f2 e0 eb    CPX #&eb
&30f4 d0 f8    BNE &30ee ; wipe_3000_to_30ea_loop
&30f6 a2 00    LDX #&00
&30f8 8a       TXA
; checksum_3100_to_31ff_loop
&30f9 18       CLC
&30fa 7d 00 31 ADC &3100,X ; payload                                # Ensure &3100 - &31ff (payload) is as expected
&30fd e8       INX                                                  # Note that &3000 - &30ff (via_decryption) is never
&30fe d0 f9    BNE &30f9 ; checksum_3100_to_31ff_loop               # checked, so could be trapped at &30e6 - &30ff

; payload
&3100 cd 00 32 CMP &3200 ; expected_checksum
&3103 f0 03    BEQ &3108 ; checksum_matches
; to_reset
&3105 6c fc ff JMP (&fffc) ; os_reset_address                       # Reset system if payload not as expected
; checksum_matches
&3108 2c e5 fe BIT &fee5 ; tube ULA data register 3                 # Reset system if second processor present ?
&310b 10 f8    BPL &3105 ; to_reset
; reset_vector_table                                                # Reset all vectors to OS defaults
&310d ad b7 ff LDA &ffb7 ; os_rom_default_vector_table_address_low
&3110 85 10    STA &10 ; default_vector_table_address_low
&3112 ad b8 ff LDA &ffb8 ; os_rom_default_vector_table_address_high
&3115 85 11    STA &11 ; default_vector_table_address_high
&3117 ac b9 ff LDY &ffb9 ; OSRDRM                                   # Bug: should be &ffb6, os_rom_vector_table_length
; reset_vector_table_loop
&311a b1 10    LDA (&10),Y ; default_vector_table_address
&311c 99 00 02 STA &0200,Y ; os_vector_table
&311f 88       DEY
&3120 10 f8    BPL &311a ; reset_vector_table_loop
; check_roms
&3122 a2 00    LDX #&00
; check_roms_loop
&3124 8e 30 fe STX &fe30 ; paged ROM latch                          # Check each ROM in turn
&3127 ad 09 80 LDA &8009 ; rom_title_string
&312a 29 df    AND #&df
&312c c9 52    CMP #&52 ; "R"
&312e d0 12    BNE &3142
&3130 ad 0a 80 LDA &800a ; rom_title_string + 1
&3133 29 df    AND #&df
&3135 c9 45    CMP #&45 ; "E"
&3137 d0 09    BNE &3142
&3139 ad 0b 80 LDA &800b ; rom_title_string + 2
&313c 29 df    AND #&df
&313e c9 50    CMP #&50 ; "P"
&3140 f0 c3    BEQ &3105 ; to_reset                                 # Reset system if Replay ROM detected
&3142 e8       INX
&3143 d0 df    BNE &3124 ; check_roms_loop
; make_cypher_table                                                 # Make a pseudo-random table at &0600 - &06ff
&3145 a9 df    LDA #&df                                             # Set User VIA timer 2 to timed interrupt
&3147 2d 6b fe AND &fe6b ; User VIA auxiliary control register
&314a 8d 6b fe STA &fe6b ; User VIA auxiliary control register
&314d a9 a0    LDA #&a0                                             # Enable interrupts for User VIA timer 2
&314f 8d 6e fe STA &fe6e ; User VIA interrupt enable register
&3152 a9 00    LDA #&00
&3154 8d 68 fe STA &fe68 ; User VIA timer 2 counter LSB
&3157 8d 69 fe STA &fe69 ; User VIA timer 2 counter MSB
&315a a2 00    LDX #&00
; initialise_cypher_table_loop
&315c 8a       TXA
&315d 49 ff    EOR #&ff
&315f 9d 00 06 STA &0600,X ; cypher_table
&3162 e8       INX
&3163 d0 f7    BNE &315c ; initialise_cypher_table_loop
&3165 a2 00    LDX #&00
; scramble_cypher_table_x_loop
&3167 86 70    STX &70 ; x
&3169 a0 00    LDY #&00
; scramble_cypher_table_y_loop
&316b 84 71    STY &71 ; y
&316d ae 68 fe LDX &fe68 ; User VIA timer 2 counter LSB
&3170 bd 00 06 LDA &0600,X ; cypher_table
&3173 85 72    STA &72 ; tmp
&3175 e8       INX
&3176 bd 00 06 LDA &0600,X ; cypher_table
&3179 ca       DEX
&317a 9d 00 06 STA &0600,X ; cypher_table
&317d e8       INX
&317e a5 72    LDA &72 ; tmp
&3180 9d 00 06 STA &0600,X ; cypher_table
&3183 ac 68 fe LDY &fe68 ; User VIA timer 2 counter LSB
&3186 ae 69 fe LDX &fe69 ; User VIA timer 2 counter MSB
&3189 bd 00 06 LDA &0600,X ; cypher_table
&318c 85 72    STA &72 ; tmp
&318e b9 00 06 LDA &0600,Y ; cypher_table
&3191 9d 00 06 STA &0600,X ; cypher_table
&3194 a5 72    LDA &72 ; tmp
&3196 99 00 06 STA &0600,Y ; cypher_table
&3199 a4 71    LDY &71 ; y
&319b c8       INY
&319c d0 cd    BNE &316b ; scramble_cypher_table_y_loop
&319e a6 70    LDX &70 ; x
&31a0 e8       INX
&31a1 d0 c4    BNE &3167 ; scramble_cypher_table_x_loop
; decrypt_tape_loader
&31a3 a9 20    LDA #&20                                             # Disable interrupts for User VIA timer 2
&31a5 8d 6e fe STA &fe6e ; User VIA interrupt enable register
&31a8 a0 00    LDY #&00
&31aa 84 10    STY &10 ; target_address_low
&31ac a9 20    LDA #&20 ; &2000 = prepare_tape_loader
&31ae 85 11    STA &11 ; target_address_high
&31b0 a9 01    LDA #&01
&31b2 85 12    STA &12 ; source_address_low
&31b4 a9 32    LDA #&32 ; &3201 = encrypted_tape_loader
&31b6 85 13    STA &13 ; source_address_high
&31b8 a9 0f    LDA #&0f
&31ba 85 ff    STA &ff ; pages_to_decrypt
; decrypt_tape_loader_loop                                          # Decrypt &3201 - &4200 to &2000 - &2fff
&31bc b1 12    LDA (&12),Y ; source_address
&31be 59 00 06 EOR &0600,Y ; cypher_table                           # using previously generated pseudo-random table
&31c1 91 10    STA (&10),Y ; target_address
&31c3 8a       TXA
&31c4 91 12    STA (&12),Y ; source_address                         # Wipe encrypted data
&31c6 c8       INY
&31c7 d0 f3    BNE &31bc ; decrypt_tape_loader_loop
&31c9 e6 11    INC &11 ; target_address_high
&31cb e6 13    INC &13 ; source_address_high
&31cd c6 ff    DEC &ff ; pages_to_decrypt
&31cf 10 eb    BPL &31bc ; decrypt_tape_loader_loop
&31d1 a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&31d3 a2 03    LDX #&03 ; Clear memory on next RESET
&31d5 20 f4 ff JSR &fff4 ; OSBYTE
&31d8 a9 ff    LDA #&ff                                             # Enable all system interrupts
&31da 8d 4e fe STA &fe4e ; System VIA interrupt enable register
&31dd 4c 00 20 JMP &2000 ; prepare_tape_loader

; unused
&31e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
&31f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

; expected_checksum
&3200 00

# &3201 - &4200 is decrypted to &2000 - &2fff at &31bc

; prepare_tape_loader
&2000 a2 00    LDX #&00
; backup_zero_page_loop
&2002 b5 00    LDA &00,X                                            # Copy &0000 - &00ff to &0100 - &01ff
&2004 9d 00 01 STA &0100,X
&2007 e8       INX
&2008 10 f8    BPL &2002 ; backup_zero_page_loop
; move_loading_screen
&200a a0 00    LDY #&00
&200c 84 00    STY &00 ; target_address_low
&200e 84 02    STY &02 ; source_address_low
&2010 a9 4c    LDA #&4c ; &4c00
&2012 85 01    STA &01 ; target_address_high
&2014 a9 50    LDA #&50 ; &5000
&2016 85 03    STA &03 ; source_address_high
; move_loading_screen_loop                                          # Move &5000 - &7fff to &4c00 - &7bff
&2018 b1 02    LDA (&02),Y ; source_address
&201a 91 00    STA (&00),Y ; target_address
&201c a9 00    LDA #&00
&201e 91 02    STA (&02),Y ; source_address                         # Wipe &7c00 - &7fff as part of this
&2020 c8       INY
&2021 d0 f5    BNE &2018 ; move_loading_screen_loop
&2023 e6 01    INC &01 ; target_address_high
&2025 e6 03    INC &03 ; source_address_high
&2027 10 ef    BPL &2018 ; move_loading_screen_loop
; disable_shadow_memory
&2029 a9 72    LDA #&72 ; Specify video memory to use on next MODE change
&202b a2 01    LDX #&01 ; only use shadow memory if MODE number is > 127
&202d a0 00    LDY #&00
&202f 20 f4 ff JSR &fff4 ; OSBYTE
; create_font_data                                                  # Populate &0900 - &0bff with character definitions
&2032 a9 14    LDA #&14 ; Implode user defined character font RAM
&2034 a2 00    LDX #&00
&2036 20 f4 ff JSR &fff4 ; OSBYTE
&2039 a9 00    LDA #&00
&203b 85 00    STA &00 ; font_address_low
&203d a9 09    LDA #&09 ; &0900 = font_data
&203f 85 01    STA &01 ; font_address_high
&2041 a9 20    LDA #&20 ; " "
&2043 85 02    STA &02 ; character
; create_font_data_loop
&2045 a2 02    LDX #&02
&2047 a0 00    LDY #&00 ; &0002
&2049 a9 0a    LDA #&0a ; Read character definition
&204b 20 f1 ff JSR &fff1 ; OSWORD
&204e a0 07    LDY #&07
; copy_character_loop
&2050 b9 03 00 LDA &0003,Y ; character + 1                          # &0003 - &000a contains character definition
&2053 91 00    STA (&00),Y ; font_address
&2055 88       DEY
&2056 10 f8    BPL &2050 ; copy_character_loop
&2058 a5 00    LDA &00 ; font_address_low
&205a 18       CLC
&205b 69 08    ADC #&08
&205d 85 00    STA &00 ; font_address_low
&205f a5 01    LDA &01 ; font_address_high
&2061 69 00    ADC #&00
&2063 85 01    STA &01 ; font_address_high
&2065 e6 02    INC &02
&2067 10 dc    BPL &2045 ; create_font_data_loop
&2069 78       SEI
&206a a2 ff    LDX #&ff
&206c 9a       TXS
; relocate_tape_loader
&206d a9 bc    LDA #&bc
&206f 85 00    STA &00 ; source_address_low
&2071 a9 20    LDA #&20 ; &20bc = unrelocated_tape_loader
&2073 85 01    STA &01 ; source_address_high
&2075 a9 04    LDA #&04 ; &0400 = tape_loader
&2077 85 03    STA &03 ; target_address_high
&2079 a0 00    LDY #&00
&207b 84 02    STY &02 ; target_address_low
; relocate_tape_loader_loop                                         # Move &20bc - &24bb to &0400 - &08ff
&207d b1 00    LDA (&00),Y ; source_address
&207f 91 02    STA (&02),Y ; target_address
&2081 c8       INY
&2082 d0 f9    BNE &207d ; relocate_tape_loader_loop
&2084 e6 01    INC &01 ; source_address_high
&2086 e6 03    INC &03 ; target_address_high
&2088 a5 03    LDA &03 ; target_address_high
&208a c9 09    CMP #&09
&208c d0 ef    BNE &207d ; relocate_tape_loader_loop
&208e a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&2090 a2 03    LDX #&03
&2092 20 f4 ff JSR &fff4 ; OSBYTE
&2095 a9 7f    LDA #&7f                                             # Disable all interrupts
&2097 8d 6e fe STA &fe6e ; User VIA interrupt enable register
&209a 8d 4e fe STA &fe4e ; System VIA interrupt enable register
&209d a2 06    LDX #&06                                             # R6: Vertical displayed register
&209f a9 1a    LDA #&1a
&20a1 20 5d 06 JSR &065d ; set_video_register
&20a4 a2 0c    LDX #&0c                                             # R12: Displayed screen start address register (high)
&20a6 a9 09    LDA #&09
&20a8 20 5d 06 JSR &065d ; set_video_register
&20ab a2 0d    LDX #&0d                                             # R13: Displayed screen start address register (low)
&20ad a9 80    LDA #&80                                             # Set screen start address to &4c00
&20af 20 5d 06 JSR &065d ; set_video_register
&20b2 a2 07    LDX #&07                                             # R7: Vertical sync position
&20b4 a9 20    LDA #&20
&20b6 20 5d 06 JSR &065d ; set_video_register
&20b9 4c 00 04 JMP &0400 ; tape_loader

# &20bc - &24bc is moved to &0400 - &08ff at &207d

; tape_loader
&0400 78       SEI
&0401 20 50 06 JSR &0650 ; clear_status_area
&0404 a0 00    LDY #&00
; delay_loop
&0406 98       TYA
&0407 48       PHA
&0408 a2 ff    LDX #&ff                                             # Unnecessary code
&040a 86 60    STX &60 ; unused
&040c e8       INX
&040d 86 61    STX &61 ; unused
&040f a2 05    LDX #&05
&0411 20 08 06 JSR &0608 ; set_text_position
&0414 a9 02    LDA #&02 ; C
&0416 8d 07 06 STA &0607 ; text_colour
&0419 20 2f 06 JSR &062f ; plot_text

&041c 4c 6f 6f 6b 69 6e 67 20 66 6f 72 20 53 74 61 72 ; "Looking for Star"
&042c 20 51 75 61 6b 65 00                            ; "Quake"

&0433 68       PLA
&0434 a8       TAY
&0435 88       DEY
&0436 d0 ce    BNE &0406 ; delay_loop
&0438 58       CLI
; start_load
&0439 a2 ff    LDX #&ff
&043b 9a       TXS
&043c a2 0e    LDX #&0e                                             # Turn off CAPS LOCK LED
&043e 8e 40 fe STX &fe40 ; System VIA port B input/output register
&0441 e8       INX ; &0f                                            # Turn off SHIFT LOCK LED
&0442 8e 40 fe STX &fe40 ; System VIA port B input/output register
&0445 a9 85    LDA #&85                                             # Set to 2400 baud, switch on cassette motor
&0447 8d 10 fe STA &fe10 ; Serial ULA control register
&044a a9 1f    LDA #&1f                                             # Master reset
&044c 8d 08 fe STA &fe08 ; Cassette ACIA control register
&044f a9 1d    LDA #&1d                                             # 8 bit word, 1 stop bit, even parity, 1200 baud
&0451 8d 08 fe STA &fe08 ; Cassette ACIA control register
&0454 a0 00    LDY #&00
&0456 84 02    STY &02 ; waiting_for_start_of_data                  # Zero to indicate waiting for start of data
&0458 84 00    STY &00 ; load_address_low
&045a a9 12    LDA #&12 ; &1200                                     # Start loading main binary at &1200
&045c 85 01    STA &01 ; load_address_high
; wait_for_start_of_actual_data                                     # Actual data starts with &aa &4b &4d &00 sequence
&045e 20 64 06 JSR &0664 ; get_byte_from_tape
&0461 c9 aa    CMP #&aa
&0463 d0 f9    BNE &045e ; wait_for_start_of_actual_data
&0465 20 64 06 JSR &0664 ; get_byte_from_tape
&0468 c9 4b    CMP #&4b ; "K"
&046a d0 f2    BNE &045e ; wait_for_start_of_actual_data
&046c 20 64 06 JSR &0664 ; get_byte_from_tape
&046f c9 4d    CMP #&4d ; "M"
&0471 d0 eb    BNE &045e ; wait_for_start_of_actual_data
&0473 20 64 06 JSR &0664 ; get_byte_from_tape
&0476 c9 00    CMP #&00
&0478 d0 e4    BNE &045e ; wait_for_start_of_actual_data
&047a 85 04    STA &04 ; decryption_code_byte
&047c a9 64    LDA #&64
&047e 85 02    STA &02 ; waiting_for_start_of_data                  # Non-zero to indicate reading data
&0480 85 05    STA &05 ; bytes_remaining_in_sector                  # 100 bytes of data per sector
&0482 a9 32    LDA #&32 ; "2"
&0484 85 1e    STA &1e ; sectors
&0486 a9 35    LDA #&35 ; "5"
&0488 85 1f    STA &1f ; sectors + 1
&048a 85 20    STA &20 ; sectors + 2
&048c 20 50 06 JSR &0650 ; clear_status_area
&048f 20 6d 05 JSR &056d ; plot_sectors_left
; read_data_loop
&0492 20 64 06 JSR &0664 ; get_byte_from_tape
&0495 84 03    STY &03 ; load_address_offset
&0497 45 03    EOR &03 ; load_address_offset
&0499 45 01    EOR &01 ; load_address_high
&049b 20 2e 05 JSR &052e ; decrypt_byte
&049e 91 00    STA (&00),Y ; load_address
&04a0 c6 05    DEC &05 ; bytes_remaining_in_sector
&04a2 d0 03    BNE &04a7 ; not_new_sector
&04a4 20 3b 05 JSR &053b ; decrement_sector_count
; not_new_sector
&04a7 c8       INY
&04a8 d0 e8    BNE &0492 ; read_data_loop
&04aa e6 01    INC &01 ; load_address_high
&04ac a5 01    LDA &01 ; load_address_high
&04ae c9 76    CMP #&76 ; &7600
&04b0 d0 e0    BNE &0492 ; read_data_loop
&04b2 8c 10 fe STY &fe10 ; Serial ULA control register              # Switch off cassette motor
&04b5 20 50 06 JSR &0650 ; clear_status_area
&04b8 a9 01    LDA #&01 ; R
&04ba 8d 07 06 STA &0607 ; text_colour
&04bd a2 07    LDX #&07
&04bf 20 08 06 JSR &0608 ; set_text_position
&04c2 20 2f 06 JSR &062f ; plot_text

&04c5 54 68 69 6e 6b 69 6e 67 20 61 67 61 69 6e 2e 2e ; "Thinking again.."
&04d5 2e 00                                           ; "."

&04d7 20 00 0c JSR &0c00 ; decrypt_main_binary
&04da a9 ff    LDA #&ff                                             # Enable all system interrupts
&04dc 8d 4e fe STA &fe4e ; System VIA interrupt enable register
&04df a9 00    LDA #&00
&04e1 8d 6e fe STA &fe6e ; User VIA interrupt enable register       # ?
&04e4 8d 6b fe STA &fe6b ; User VIA auxiliary control register      # Set timer 1 and timer 2 to timed interrupts
&04e7 a2 01    LDX #&01                                             # R1: Number of characters per line
&04e9 a9 00    LDA #&00                                             # Hide screen
&04eb 20 5d 06 JSR &065d ; set_video_register
&04ee a2 07    LDX #&07                                             # R7: Vertical sync position
&04f0 a9 1f    LDA #&1f
&04f2 20 5d 06 JSR &065d ; set_video_register
&04f5 a2 06    LDX #&06                                             # R6: Vertical displayed register
&04f7 a9 18    LDA #&18
&04f9 20 5d 06 JSR &065d ; set_video_register
&04fc a2 00    LDX #&00
; restore_zero_page_loop                                            # Copy &0100 - &01ff to &0000 - &00ff
&04fe bd 00 01 LDA &0100,X
&0501 95 00    STA &00,X
&0503 e8       INX
&0504 10 f8    BPL &04fe ; restore_zero_page_loop
&0506 78       SEI
; reset_vector_table                                                # Reset all vectors to OS defaults
&0507 ac b6 ff LDY &ffb6 ; os_rom_vector_table_length
&050a ad b7 ff LDA &ffb7 ; os_rom_default_vector_table_address_low
&050d 85 10    STA &10 ; default_vector_table_address_low
&050f ad b8 ff LDA &ffb8 ; os_rom_default_vector_table_address_high
&0512 85 11    STA &11 ; default_vector_table_address_high
; reset_vector_table_loop
&0514 b1 10    LDA (&10),Y ; default_vector_table_address
&0516 99 00 02 STA &0200,Y ; os_vector_table
&0519 88       DEY
&051a 10 f8    BPL &0514 ; reset_vector_table_loop
&051c a2 01    LDX #&01                                             # R1: Number of characters per line
&051e a9 40    LDA #&40                                             # Restore screen
&0520 20 5d 06 JSR &065d ; set_video_register
&0523 58       CLI
&0524 a9 0f    LDA #&0f ; Flush all buffers
&0526 a2 00    LDX #&00
&0528 20 f4 ff JSR &fff4 ; OSBYTE
&052b 4c fc 14 JMP &14fc ; main_binary_entry_point

; decrypt_byte
&052e 48       PHA
&052f 29 55    AND #&55
&0531 0a       ASL A
&0532 85 0a    STA &0a ; tmp
&0534 68       PLA
&0535 29 aa    AND #&aa
&0537 4a       LSR A
&0538 05 0a    ORA &0a ; tmp
&053a 60       RTS

; decrement_sector_count
&053b 20 64 06 JSR &0664 ; get_byte_from_tape
&053e 20 2e 05 JSR &052e ; decrypt_byte
&0541 a6 04    LDX &04 ; decryption_code_byte
&0543 9d 00 0c STA &0c00,X ; decryption_main_binary                 # One byte of decryption code per sector
&0546 e6 04    INC &04 ; decryption_code_byte
&0548 a9 64    LDA #&64
&054a 85 05    STA &05 ; bytes_remaining_in_sector
&054c c6 20    DEC &20 ; sectors + 2
&054e a5 20    LDA &20 ; sectors + 2
&0550 c9 2f    CMP #&2f ; "0" - 1
&0552 d0 19    BNE &056d ; plot_sectors_left
&0554 a9 39    LDA #&39 ; "9"
&0556 85 20    STA &20 ; sectors + 2
&0558 c6 1f    DEC &1f ; sectors + 1
&055a a5 1f    LDA &1f ; sectors + 1
&055c c9 2f    CMP #&2f ; "0" - 1
&055e d0 0d    BNE &056d ; plot_sectors_left
&0560 a9 39    LDA #&39 ; "9"
&0562 85 1f    STA &1f ; sectors + 1
&0564 c6 1e    DEC &1e ; sectors
&0566 a5 1e    LDA &1e ; sectors
&0568 c9 2f    CMP #&2f ; "0" - 1
&056a d0 01    BNE &056d ; plot_sectors_left                        # Always branches
&056c 60       RTS

; plot_sectors_left
&056d 98       TYA
&056e 48       PHA
&056f a2 07    LDX #&07
&0571 20 08 06 JSR &0608 ; set_text_position
&0574 a9 03    LDA #&03 ; W
&0576 8d 07 06 STA &0607 ; text_colour
&0579 20 2f 06 JSR &062f ; plot_text

&057c 53 65 63 74 6f 72 73 20 6c 65 66 74 20 3a 00 ; "Sectors left :"

&058b a5 1e    LDA &1e ; sectors
&058d 20 9d 05 JSR &059d ; plot_character
&0590 a5 1f    LDA &1f ; sectors + 1
&0592 20 9d 05 JSR &059d ; plot_character
&0595 a5 20    LDA &20 ; sectors + 2
&0597 20 9d 05 JSR &059d ; plot_character
&059a 68       PLA
&059b a8       TAY
&059c 60       RTS

; plot_character
&059d 38       SEC
&059e e9 20    SBC #&20
&05a0 85 28    STA &28 ; font_address_low
&05a2 a9 00    LDA #&00
&05a4 06 28    ASL &28 ; font_address_low
&05a6 2a       ROL A
&05a7 06 28    ASL &28 ; font_address_low
&05a9 2a       ROL A
&05aa 06 28    ASL &28 ; font_address_low
&05ac 2a       ROL A
&05ad 69 09    ADC #&09 ; &0900 = font_data                         # &900 + 8 * (character - 32)
&05af 85 29    STA &29 ; font_address_high
&05b1 a5 2a    LDA &2a ; screen_address_low
&05b3 18       CLC
&05b4 69 08    ADC #&08
&05b6 85 2c    STA &2c ; right_screen_address_low
&05b8 a5 2b    LDA &2b ; screen_address_high
&05ba 69 00    ADC #&00
&05bc 85 2d    STA &2d ; right_screen_address_high
&05be 98       TYA
&05bf 48       PHA
&05c0 a0 07    LDY #&07
; plot_character_loop
&05c2 b1 28    LDA (&28),Y ; font_address
&05c4 4a       LSR A
&05c5 4a       LSR A
&05c6 4a       LSR A
&05c7 4a       LSR A
&05c8 20 e9 05 JSR &05e9 ; multiply_font_byte_by_colour
&05cb 91 2a    STA (&2a),Y ; screen_address
&05cd b1 28    LDA (&28),Y ; font_address
&05cf 29 0f    AND #&0f
&05d1 20 e9 05 JSR &05e9 ; multiply_font_byte_by_colour
&05d4 91 2c    STA (&2c),Y ; right_screen_address
&05d6 88       DEY
&05d7 10 e9    BPL &05c2 ; plot_character_loop
&05d9 a5 2a    LDA &2a ; screen_address_low
&05db 18       CLC
&05dc 69 10    ADC #&10
&05de 85 2a    STA &2a ; screen_address_low
&05e0 a5 2b    LDA &2b ; screen_address_high
&05e2 69 00    ADC #&00
&05e4 85 2b    STA &2b ; screen_address_high
&05e6 68       PLA
&05e7 a8       TAY
&05e8 60       RTS

; multiply_font_byte_by_colour
&05e9 ae 07 06 LDX &0607 ; text_colour
&05ec f0 17    BEQ &0605 ; is_zero
&05ee e0 01    CPX #&01
&05f0 d0 01    BNE &05f3 ; is_two_or_three
; is_one
&05f2 60       RTS                                                  # Leave with A
; is_two_or_three
&05f3 e0 02    CPX #&02
&05f5 d0 05    BNE &05fc ; is_three
&05f7 0a       ASL A
&05f8 0a       ASL A
&05f9 0a       ASL A
&05fa 0a       ASL A
&05fb 60       RTS                                                  # Leave with A * 16
; is_three
&05fc 85 2e    STA &2e ; a
&05fe 0a       ASL A
&05ff 0a       ASL A
&0600 0a       ASL A
&0601 0a       ASL A
&0602 05 2e    ORA &2e ; a
&0604 60       RTS                                                  # Leave with A * 17
; is_zero
&0605 8a       TXA
&0606 60       RTS                                                  # Leave with zero

; text_colour
&0607 00

; set_text_position
&0608 86 2c    STX &2c ; x
&060a a9 00    LDA #&00
&060c 85 2a    STA &2a ; screen_address_low
&060e a9 7e    LDA #&7e ; &7e00
&0610 85 2b    STA &2b ; screen_address_high
&0612 a9 00    LDA #&00
&0614 06 2c    ASL &2c ; x
&0616 2a       ROL A
&0617 06 2c    ASL &2c ; x
&0619 2a       ROL A
&061a 06 2c    ASL &2c ; x
&061c 2a       ROL A
&061d 85 2d    STA &2d ; x_high
&061f 06 2c    ASL &2c ; x
&0621 2a       ROL A
&0622 a5 2a    LDA &2a ; screen_address_low
&0624 65 2c    ADC &2c ; x
&0626 85 2a    STA &2a ; screen_address_low
&0628 a5 2b    LDA &2b ; screen_address_high
&062a 65 2d    ADC &2d ; x_high
&062c 85 2b    STA &2b ; screen_address_high
&062e 60       RTS

; plot_text
&062f 68       PLA
&0630 85 32    STA &32 ; text_address_low
&0632 68       PLA
&0633 85 33    STA &33 ; text_address_high
&0635 a0 00    LDY #&00
; plot_text_loop
&0637 e6 32    INC &32
&0639 d0 02    BNE &063d ; skip_page
&063b e6 33    INC &33 ; text_address_high
; skip_page
&063d b1 32    LDA (&32),Y ; text_address
&063f f0 06    BEQ &0647 ; leave_after_text
&0641 20 9d 05 JSR &059d ; plot_character
&0644 4c 37 06 JMP &0637 ; plot_text_loop
; leave_after_text
&0647 e6 32    INC &32 ; text_address_low
&0649 d0 02    BNE &064d ; skip_page
&064b e6 33    INC &33 ; text_address_high
; skip_page
&064d 6c 32 00 JMP (&0032) ; text_address                           # Return after end of string

; clear_status_area
&0650 a2 00    LDX #&00
&0652 8a       TXA
; clear_status_area_loop
&0653 9d 00 7e STA &7e00,X                                          # Wipe &7e00 - &7fff
&0656 9d 00 7f STA &7f00,X
&0659 e8       INX
&065a d0 f7    BNE &0653 ; clear_status_area_loop
&065c 60       RTS

; set_video_register
&065d 8e 00 fe STX &fe00 ; video register number
&0660 8d 01 fe STA &fe01 ; video register value
&0663 60       RTS

; get_byte_from_tape
&0664 ad 08 fe LDA &fe08 ; Cassette ACIA status register
&0667 29 70    AND #&70                                             # Is there a framing, receiver overrun or parity error?
&0669 f0 04    BEQ &066f ; not_error
&066b a5 02    LDA &02 ; waiting_for_start_of_data
&066d d0 0b    BNE &067a ; load_error                               # Non-zero if reading data
; not_error
&066f ad 08 fe LDA &fe08 ; Cassette ACIA status register
&0672 29 01    AND #&01                                             # Is it a receiver interrupt?
&0674 f0 ee    BEQ &0664 ; get_byte_from_tape
&0676 ad 09 fe LDA &fe09 ; Cassette ACIA data register              # If so, return a byte of data
&0679 60       RTS
; load_error
&067a 20 50 06 JSR &0650 ; clear_status_area
&067d a9 00    LDA #&00                                             # Switch off cassette motor
&067f 8d 10 fe STA &fe10 ; Serial ULA control register
&0682 a9 01    LDA #&01 ; R
&0684 8d 07 06 STA &0607 ; text_colour
&0687 a2 07    LDX #&07
&0689 20 08 06 JSR &0608 ; set_text_position
&068c 20 2f 06 JSR &062f ; plot_text

&068f 50 75 74 20 74 61 70 65 20 74 6f 20 73 74 61 72 ; "Put tape to star"
&069f 74 00                                           ; "t"

&06a1 4c 39 04 JMP &0439 ; start_load                               # Restart the load

; unused
&3561 98 66 11 21 fd ee 21                                          # Not meaningful either encrypted or decrypted

# Text decrypted by decrypt_3000_to_35ff

&3568 2a 2a 2a 20 4f 6b 61 79 2c 20 73 6f 20 79 6f 75 ; "*** Okay, so you"
&3578 20 67 6f 74 20 70 61 73 74 20 74 68 65 20 65 61 ; " got past the ea"
&3588 73 79 20 62 69 74 2c 20 62 69 67 20 68 61 73 73 ; "sy bit, big hass"
&3598 6c 65 20 2a 2a 2a 20 54 68 61 6e 6b 73 20 74 6f ; "le *** Thanks to"
&35a8 20 47 61 72 79 20 50 61 72 74 69 73 20 66 6f 72 ; " Gary Partis for"
&35b8 20 64 6f 69 6e 67 20 74 68 65 20 72 65 61 6c 20 ; " doing the real "
&35c8 70 72 6f 74 65 63 74 69 6f 6e 20 61 74 20 74 68 ; "protection at th"
&35d8 65 20 6c 61 73 74 20 6d 69 6e 75 74 65 20 2a 2a ; "e last minute **"
&35e8 2a 20 42 79 20 4b 65 6e 74 6f 6e 20 50 72 69 63 ; "* By Kenton Pric"
&35f8 65 20 2a 2a 2a 00 ff cc                         ; "e ***..."

Decryption code read one byte at end of each sector:

; decrypt_main_binary
&0c00 78       SEI
&0c01 d8       CLD
&0c02 a9 df    LDA #&df                                             # Set User VIA timer 2 to timed interrupt
&0c04 2d 6b fe AND &fe6b ; User VIA auxiliary control register
&0c07 8d 6b fe STA &fe6b ; User VIA auxiliary control register
&0c0a a9 a0    LDA #&a0                                             # Enable interrupts for User VIA timer 2
&0c0c 8d 6e fe STA &fe6e ; User VIA interrupt enable register
&0c0f a9 00    LDA #&00
&0c11 8d 68 fe STA &fe68 ; User VIA timer 2 counter LSB
&0c14 8d 69 fe STA &fe69 ; User VIA timer 2 counter MSB
&0c17 a2 04    LDX #&04                                             # 4 rounds
; decrypt_main_binary_loop
&0c19 86 60    STX &60 ; round
&0c1b ad 69 fe LDA &fe69 ; User VIA timer 2 counter MSB
&0c1e 48       PHA
&0c1f ad 68 fe LDA &fe68 ; User VIA timer 2 counter LSB
&0c22 8d 69 fe STA &fe69 ; User VIA timer 2 counter MSB
&0c25 68       PLA
&0c26 8d 68 fe STA &fe68 ; User VIA timer 2 counter LSB
&0c29 8a       TXA
&0c2a 18       CLC
&0c2b 6d 68 fe ADC &fe68 ; User VIA timer 2 counter LSB
&0c2e a8       TAY
&0c2f ad 00 12 LDA &1200                                            # Start decryption at &1200
#     actually LDA source_address
&0c32 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&0c35 5d 00 0c EOR &0c00,X ; decrypt_main_binary                    # Runs over &0c01 - &0c04
&0c38 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&0c3b 49 ff    EOR #&ff
#     actually EOR decrypt_eor_one
&0c3d 45 60    EOR &60 ; round
&0c3f 48       PHA
&0c40 ad 68 fe LDA &fe68 ; User VIA timer 2 counter LSB
&0c43 38       SEC
&0c44 6d 69 fe ADC &fe69 ; User VIA timer 2 counter MSB
&0c47 49 55    EOR #&55                                             # Fixed value, inverts even bits
&0c49 8d 68 fe STA &fe68 ; User VIA timer 2 counter LSB
&0c4c 68       PLA
&0c4d 59 00 0c EOR &0c00,Y ; decrypt_main_binary                    # Runs over &0c00 - &0cff
&0c50 ac 30 0c LDY &0c30 ; source_address_low
&0c53 59 00 0c EOR &0c00,Y ; decrypt_main_binary                    # Runs over &0c00 - &0cff
&0c56 49 00    EOR #&00
#     actually EOR decrypt_eor_two
&0c58 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&0c5b 4d 80 0c EOR &0c80
#     actually EOR &0c00 + decrypt_offset_one                       # Runs over &0c00 - &0cff
&0c5e ee 5c 0c INC &0c5c ; decrypt_offset_one
&0c61 ac 68 fe LDY &fe68 ; User VIA timer 2 counter LSB
&0c64 59 00 0c EOR &0c00,Y ; decrypt_main_binary                    # Runs over &0c00 - &0cff
&0c67 49 ff    EOR #&ff
#     actually EOR decrypt_eor_three
&0c69 ac 69 fe LDY &fe69 ; User VIA timer 2 counter MSB
&0c6c 59 00 0c EOR &0c00,Y ; decrypt_main_binary                    # Runs over &0c00 - &0cff
&0c6f c8       INY
&0c70 4d 00 0c EOR &0c00 ; decrypt_main_binary
#     actually EOR &0c00 + decrypt_offset_two                       # Runs over &0c00 - &0cff
&0c73 48       PHA
&0c74 ad 71 0c LDA &0c71 ; decrypt_offset_two
&0c77 6d 68 fe ADC &fe68 ; User VIA timer 2 counter LSB
&0c7a 8d 71 0c STA &0c71 ; decrypt_offset_two
&0c7d 68       PLA
&0c7e 48       PHA
&0c7f b9 00 0c LDA &0c00,Y ; decrypt_main_binary                    # Runs over &0c00 - &0cff
&0c82 5d 00 0c EOR &0c00,X ; decrypt_main_binary                    # Runs over &0c00 - &0cff
&0c85 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&0c88 4d 69 fe EOR &fe69 ; User VIA timer 2 counter MSB
&0c8b 8d 90 0c STA &0c90 ; decrypt_eor_four
&0c8e 68       PLA
&0c8f 49 00    EOR #&00
#     actually EOR decrypt_eor_four
&0c91 ee 95 0c INC &0c95 ; decrypt_eor_five
&0c94 49 5d    EOR #&5d
#     actually EOR decrypt_eor_five
&0c96 5d 00 0c EOR &0c00,X ; decrypt_main_binary                    # Runs over &0c01 - &0c04
&0c99 49 26    EOR #&26
#     actually EOR decrypt_eor_six
&0c9b 8d 00 12 STA &1200
#     actually STA target_address
&0c9e ad 68 0c LDA &0c68 ; decrypt_eor_three
&0ca1 18       CLC
&0ca2 6d 68 fe ADC &fe68 ; User VIA timer 2 counter LSB
&0ca5 49 55    EOR #&55                                             # Fixed value, inverts even bits
&0ca7 8d 68 0c STA &0c68 ; decrypt_eor_three
&0caa ad 3c 0c LDA &0c3c ; decrypt_eor_one
&0cad ed 69 fe SBC &fe69 ; User VIA timer 2 counter MSB
&0cb0 49 aa    EOR #&aa                                             # Fixed value, inverts odd bits
&0cb2 8d 3c 0c STA &0c3c ; decrypt_eor_one
&0cb5 ad 57 0c LDA &0c57 ; decrypt_eor_two
&0cb8 ed 68 fe SBC &fe68 ; User VIA timer 2 counter LSB
&0cbb 6d 69 fe ADC &fe69 ; User VIA timer 2 counter MSB
&0cbe 4d 68 fe EOR &fe68 ; User VIA timer 2 counter LSB
&0cc1 0d 69 fe ORA &fe69 ; User VIA timer 2 counter MSB
&0cc4 8d 57 0c STA &0c57 ; decrypt_eor_two
&0cc7 ad 9a 0c LDA &0c9a ; decrypt_eor_six
&0cca 6d 68 fe ADC &fe68 ; User VIA timer 2 counter LSB
&0ccd f9 00 0c SBC &0c00,Y ; decrypt_main_binary                    # Runs over &0c00 - &0cff
&0cd0 5d 00 0c EOR &0c00,X ; decrypt_main_binary                    # Runs over &0c01 - &0c04
&0cd3 8d 9a 0c STA &0c9a ; decrypt_eor_six
&0cd6 ee 31 0c INC &0c31 ; source_address_high                      # Decrypt &1200, &1300, &1400, ... &7f00
&0cd9 ee 9d 0c INC &0c9d ; target_address_high
&0cdc 30 03    BMI &0ce1 ; wrap_address
&0cde 4c 19 0c JMP &0c19 ; decrypt_main_binary_loop
; wrap_address
&0ce1 a9 20    LDA #&20                                             # then continue decryption at &2001, &2101, &2201, ...
&0ce3 8d 31 0c STA &0c31 ; source_address_high                      # Bug: &1201 - &12ff, &1301 - &13ff, etc, not decrypted
&0ce6 8d 9d 0c STA &0c9d ; target_address_high
&0ce9 ee 30 0c INC &0c30 ; source_address_low
&0cec ee 9c 0c INC &0c9c ; target_address_low
&0cef f0 03    BEQ &0cf4 ; next_round
&0cf1 4c 19 0c JMP &0c19 ; decrypt_main_binary_loop
; next_round
&0cf4 ca       DEX
&0cf5 f0 03    BEQ &0cfa ; disable_interrupt_and_leave
&0cf7 4c 19 0c JMP &0c19 ; decrypt_main_binary_loop
; disable_interrupt_and_leave
&0cfa a9 20    LDA #&20                                             # Disable interrupts for User VIA timer 2
&0cfc 8d 6e fe STA &fe6e ; User VIA interrupt enable register
&0cff 60       RTS

Game disassembly
================
; (no filename)
; 001200 0014fc 006400

; &0000 - &000a keys
; &000b - &000c adventure_score
; &000d         gate_screen_address_low
; &000e         (unused)
; &000f - &0012 pockets
; &0013 - &0016 previous_pockets
; &0017 - &001f core_elements_required
; &0020         player_touching_death
; &0021         previous_player_on_hopper
; &0022         player_facing
; &0023         game_time_countdown
; &0024         game_time_low
; &0025         game_time_high
; &0026         player_room_history
; &0027         player_room_history + 1
; &0028         player_room_history + 2
; &0029         player_room_history + 3
; &002a         new_enemies_cooldown_history
; &002b         new_enemies_needed_history
; &002c         new_enemies_cooldown_history + 2
; &002d         new_enemies_needed_history + 2
; &002e         new_enemies_cooldown
; &002f         new_enemies_needed
; &0030 - &0032 previous_score
; &0031         previous_player_lives
; &0034 - &0039 previous_player_energy_low
; &003a - &003f player_energy_low
; &0040         enemy_previous_screen_address_low
; &0041         enemy_previous_screen_address_high
; &0042         enemy_previous_type
; &0043         enemy_previous_animation
; &0044         only_unplot_enemies
; &0045         player_walking_direction
; &0046 - &0048 score
; &0049         player_lives
; &004a         passage_direction
; &004b         passage_destination_room_low
; &004c         passage_screen_address_low
; &004d         passage_screen_address_high
; &004e         passage_destination_screen_address_low
; &004f         passage_destination_screen_address_high
; &0050         previous_cfs_timeout_counter
; &0051 - &0052 (unused)
; &0053         room_item_data_address_low
; &0054         room_item_data_address_high
; &0055         room_item_colour_mask
; &0056         room_item_sprite
; &0057         room_item_unused
; &0058         room_item_screen_address_low
; &0059         room_item_screen_address_high
; &005a         player_entry_screen_address_low
; &005b         player_entry_screen_address_high
; &005c         player_entry_sprite
; &005d         player_entry_on_platform
; &005e - &0063 (unused)
; &0064         hopper_pad_screen_address_low
; &0065         hopper_pad_screen_address_high

; &0090 - &0097 palette
; &0098         player_group_address_low
; &0099         hopper_sprite
; &009a         rnd_1
; &009b         rnd_2
; &009c         rnd_3
; &009d         rnd_4
; &009e         player_in_pipe
; &009f         core_elements_placed
; &00a0 - &00ab (unused)
; &00ac         space_lock_entrance_screen_address_low
; &00ad         space_lock_entrance_screen_address_high
; &00ae         space_lock_entrance_screen_address_low + 2
; &00af         space_lock_entrance_screen_address_high + 2

; &0100 - &011f spark_data
;     Eight bytes per spark
;         &0100 sparks_screen_address_low
;         &0101 sparks_screen_address_high
;         &0102 sparks_subtile_address_low                          # Set but not used
;         &0103 sparks_subtile_address_high                         # Set but not used
;         &0104 sparks_frame
;         &0105 sparks_ignition_frame
;         &0106 sparks_total_frames
;         &0107 (unused)

; &0120 - &014f pipe_in_tile
; &0150 - &0157 pipe_arrow_columns_status


; &0158 - &0187 previous_enemies_data
; &0188 - &01b7 enemies_data (four enemies, twelve bytes per enemy)
;         &0188 enemies_screen_address_low
;         &0189 enemies_screen_address_high
;         &018a enemies_type
;         &018b enemies_direction
;         &018c enemies_inertia
;         &018d enemies_maximum_homing_cooldown
;         &018e enemies_behaviour
;         &018f enemies_move_cooldown
;         &0190 enemies_homing_cooldown
;         &0191 enemies_materialisation_timer
;         &0192 enemies_animation
;         &0193 enemies_materialising

; &01c8 - &01d0 player_subtiles

; &0380 - &03ff rooms_visited

; &0400 - &042f room_tiles

; &0400 - &041f bridging_platform_data
;     Two bytes per platform:
;         84218421 ........ subtile_address_low
;         ........ ......21 subtile_address_high
;         ........ 842184.. time to live

; &0528 - &0577 core_elements_data
;     Four bytes per element:
;         84218421 ........ ........ ........ room_low
;         ........ ......21 ........ ........ room_high
;         ........ 842184.. ........ ........ screen_address_low
;         ........ ........ 84218421 ........ screen_address_high
;         ........ ........ ........ 84218421 sprite

; &05a0 - &07df room_subtiles

; &0c00 - &0dff item_data
;     Two bytes per item:
;         84218421 8....... room (low, high)
;         ........ .4218421 screen address

; &6600 - &7eff screen memory

# &1200 - &6fff is decrypted to &0e00 - &6bff at &7518

; prepare_teleport_or_pyramid_screen
&0e00 20 11 0f JSR &0f11 ; clear_screen_and_flush_buffers
; choose_random_colour_one
&0e03 20 40 64 JSR &6440 ; rnd
&0e06 29 07    AND #&07
&0e08 c9 05    CMP #&05
&0e0a b0 f7    BCS &0e03 ; choose_random_colour_one
&0e0c 85 93    STA &93 ; palette + 3                                # Set colour one of bottom section
; choose_random_colour_two
&0e0e 20 40 64 JSR &6440 ; rnd
&0e11 29 07    AND #&07
&0e13 c5 93    CMP &93 ; palette + 3
&0e15 f0 f7    BEQ &0e0e ; choose_random_colour_two
&0e17 c9 05    CMP #&05
&0e19 b0 f3    BCS &0e0e ; choose_random_colour_two
&0e1b 69 01    ADC #&01
&0e1d 85 95    STA &95 ; palette + 5                                # Set colour two of bottom section
&0e1f e6 93    INC &93 ; palette + 3
&0e21 20 00 7f JSR &7f00 ; to_set_screen_colours
; play_enter_teleport_sound
&0e24 a2 14    LDX #&14
&0e26 a0 10    LDY #&10 ; &1014 = enter_teleport_sound
&0e28 4c 2b 35 JMP &352b ; play_sound_using_envelope

; enter_teleport
&0e2b a2 00    LDX #&00
&0e2d a4 f5    LDY &f5 ; room_teleport_offset
; poke_teleport_code_loop
&0e2f b9 1d 62 LDA &621d,Y ; teleport_data - 8                      # Poke teleport code into text
&0e32 9d 52 0f STA &0f52,X ; teleport_text + &2c
&0e35 c8       INY
&0e36 e8       INX
&0e37 e0 05    CPX #&05
&0e39 d0 f4    BNE &0e2f ; poke_teleport_code_loop
&0e3b 20 00 0e JSR &0e00 ; prepare_teleport_or_pyramid_screen
&0e3e a9 24    LDA #&24
&0e40 85 8c    STA &8c ; sprite_address_low
&0e42 a9 61    LDA #&61 ; &6124 = tile_sprite_25
&0e44 85 8d    STA &8d ; sprite_address_high
&0e46 a9 d0    LDA #&d0
&0e48 85 8e    STA &8e ; screen_address_low
&0e4a a9 6f    LDA #&6f ; &6fd0
&0e4c 85 8f    STA &8f ; screen_address_high
&0e4e a2 04    LDX #&04                                             # 16 pixels wide
&0e50 a0 03    LDY #&03                                             # 24 pixels high
&0e52 20 00 65 JSR &6500 ; plot_aligned_sprite_using_write          # Plot teleport sprite
&0e55 a2 26    LDX #&26
&0e57 a0 0f    LDY #&0f ; &0f26 = teleport_text
&0e59 20 80 0a JSR &0a80 ; plot_text
&0e5c a9 00    LDA #&00
&0e5e 85 86    STA &86 ; input_offset
; get_character
&0e60 20 e0 ff JSR &ffe0 ; OSRDCH
&0e63 29 5f    AND #&5f                                             # Convert to uppercase
&0e65 c9 41    CMP #&41 ; "A"
&0e67 90 f7    BCC &0e60 ; get_character
&0e69 c9 5b    CMP #&5b ; "Z" + 1
&0e6b b0 f3    BCS &0e60 ; get_character                            # Get a character between "A" and "Z"
&0e6d a6 86    LDX &86 ; input_offset
&0e6f 9d 90 0f STA &0f90,X ; entered_code
&0e72 8d 95 0f STA &0f95 ; character_entered_text
&0e75 a2 95    LDX #&95
&0e77 a0 0f    LDY #&0f ; &0f95 = character_entered_text
&0e79 20 80 0a JSR &0a80 ; plot_text                                # Display character
&0e7c a2 1e    LDX #&1e
&0e7e a0 0f    LDY #&0f ; &0f1e = character_entered_sound
&0e80 20 3d 35 JSR &353d ; play_sound
&0e83 e6 86    INC &86 ; input_offset
&0e85 a5 86    LDA &86 ; input_offset
&0e87 c9 05    CMP #&05
&0e89 d0 d5    BNE &0e60 ; get_character
&0e8b a0 08    LDY #&08
; check_teleport_codes_loop
&0e8d a2 00    LDX #&00
; check_characters_loop
&0e8f b9 1d 62 LDA &621d,Y ; teleport_data - 8                      # Does the entered code match any teleport code?
&0e92 dd 90 0f CMP &0f90,X ; entered_code
&0e95 d0 08    BNE &0e9f ; consider_next_code
&0e97 c8       INY
&0e98 e8       INX
&0e99 e0 05    CPX #&05
&0e9b d0 f2    BNE &0e8f ; check_characters_loop
&0e9d f0 13    BEQ &0eb2 ; code_matches
; consider_next_code
&0e9f 98       TYA
&0ea0 18       CLC
&0ea1 69 08    ADC #&08
&0ea3 29 f8    AND #&f8
&0ea5 a8       TAY
&0ea6 10 e5    BPL &0e8d ; check_teleport_codes_loop
&0ea8 20 17 0f JSR &0f17 ; play_error_sound
&0eab a5 f5    LDA &f5 ; room_teleport_offset                       # If not, return to current room
&0ead 48       PHA
&0eae a2 98    LDX #&98 ; &0f98 = code_not_recognised_text          # and display an error
&0eb0 d0 0d    BNE &0ebf ; flash_text
; code_matches
&0eb2 98       TYA
&0eb3 29 f8    AND #&f8
&0eb5 48       PHA                                                  # Otherwise, return to destination room
&0eb6 a2 59    LDX #&59
&0eb8 a0 04    LDY #&04 ; &0459 = teleporting_sound
&0eba 20 2b 35 JSR &352b ; play_sound_using_envelope
&0ebd a2 b0    LDX #&b0 ; &0fb0 = now_teleporting_text
; flash_text
&0ebf a9 d5    LDA #&d5
&0ec1 85 86    STA &86 ; timer
&0ec3 86 7e    STX &7e ; text_address_low
; flash_text_loop
&0ec5 a5 86    LDA &86 ; timer
&0ec7 29 03    AND #&03                                             # Cycle through all four colours
&0ec9 09 80    ORA #&80                                             # Top bit set to set colour
&0ecb 8d b0 0f STA &0fb0 ; now_teleporting_text
&0ece 8d 98 0f STA &0f98 ; code_not_recognised_text
&0ed1 a6 7e    LDX &7e ; text_address_low
&0ed3 a0 0f    LDY #&0f
&0ed5 20 80 0a JSR &0a80 ; plot_text
&0ed8 a9 13    LDA #&13 ; Wait for v-sync
&0eda 20 f4 ff JSR &fff4 ; OSBYTE
&0edd e6 86    INC &86 ; timer
&0edf d0 e4    BNE &0ec5 ; flash_text_loop
&0ee1 68       PLA ; teleport_offset
&0ee2 a8       TAY
&0ee3 b9 24 62 LDA &6224,Y ; teleport_data - 1                      # Top nibble of last byte of teleport data
&0ee6 4a       LSR A
&0ee7 4a       LSR A
&0ee8 4a       LSR A
&0ee9 4a       LSR A
&0eea 85 8e    STA &8e ; tmp
&0eec 0a       ASL A
&0eed 65 8e    ADC &8e ; tmp                                        # sets y position of destination tile
&0eef 69 6e    ADC #&6e
&0ef1 85 71    STA &71 ; player_screen_address_high
&0ef3 b9 24 62 LDA &6224,Y ; teleport_data - 1                      # Bottom nibble of last byte of teleport data
&0ef6 4a       LSR A                                                # (excluding bottom bit)
&0ef7 0a       ASL A
&0ef8 0a       ASL A
&0ef9 0a       ASL A
&0efa 0a       ASL A
&0efb 0a       ASL A
&0efc 38       SEC
&0efd e9 08    SBC #&08
&0eff 85 70    STA &70 ; player_screen_address_low                  # sets x position of destination tile
&0f01 a9 0b    LDA #&0b
&0f03 85 72    STA &72 ; player_sprite                              # Player faces right, one step out of teleport
&0f05 b9 23 62 LDA &6223,Y ; teleport_data - 2
&0f08 85 7e    STA &7e ; player_room_low                            # Second last byte of teleport data
&0f0a b9 24 62 LDA &6224,Y ; teleport_data - 1
&0f0d 29 01    AND #&01                                             # and bottom bit of last byte of teleport data
&0f0f 85 7f    STA &7f ; player_room_high                           # set destination room
; clear_screen_and_flush_buffers
&0f11 20 78 34 JSR &3478 ; clear_screen
&0f14 4c 24 35 JMP &3524 ; flush_buffers

; play_error_sound
&0f17 a2 c4    LDX #&c4
&0f19 a0 0f    LDY #&0f ; &0fc4 = error_sound
&0f1b 4c 2b 35 JMP &352b ; play_sound_using_envelope

; character_entered_sound
;     chan  vol   pitch dur
&0f1e 10 00 f1 00 01 00 01 00

; teleport_text
&0f26 81
&0f27 1f 03 07
&0f2a 59 4f 55 00 00 48 41 56 45 00 00 45 4e 54 45 52 ; "YOU  HAVE  ENTERED"
&0f3a 45 44
&0f3c 1f 13 09
&0f34 54 45 4c 45 50 4f 52 54                         ; "TELEPORT"
&0f47 1f 0a 0b
&0f4a 43 4f 44 45 5b 6b 5b                            ; "CODE : "
&0f51 83
&0f52 28 43 29 4b 50                                  ; "(C)KP"     # Overwritten by teleport code
&0f57 1f 0c 0e
&0f5a 82
&0f5b 45 4e 54 45 52 5b 54 45 4c 45 50 4f 52 54 41 4c ; "ENTER TELEPORTAL"
&0f6b 1f 0c 10
&0f6e 44 45 53 54 49 4e 41 54 49 4f 4e 5b 43 4f 44 45 ; "DESTINATION CODE"
&0f7e 1f 1a 13
&0f81 83
&0f82 6d 5b 6d 5b 6d 5b 6d 5b 6d 81                   ; "_ _ _ _ _"
&0f8c 1f 1a 13
&0f8f 0d

; entered_code
&0f90 00 00 00 00 00

; character_entered_text
&0f95 5b 5b                                           ; "  "
&0f97 0d

; code_not_recognised_text
&0f98 81
&0f99 1f 05 15
&0f9c 43 4f 44 45 5b 4e 4f 54 5b 52 45 43 4f 47 4e 49 ; "CODE NOT RECOGNISED"
&0fac 53 45 44
&0faf 0d

; now_teleporting_text
&0fb0 81
&0fb1 1f 0e 15
&0fb3 4e 4f 57 5b 54 45 4c 45 50 4f 52 54 49 4e 47    ; "NOW TELEPORTING"
&0fc3 0d

; error_sound
&0fc4 04 01 0a 14 1e 01 01 01 7e 00 00 82 7e 7e
;     chan  vol   pitch dur
&0fd2 11 00 04 00 c0 00 1e 00

; cheops_pyramid_text
&0fda 1f 0e 08
&0fdd 82
&0fde 43 48 45 4f 50 53 5b 50 59 52 41 4d 49 44       ; "CHEOPS PYRAMID"
&0fec 1f 0e 0c
&0fef 81
&0ff0 45 58 43 48 41 4e 47 45 5b 5b 5b 46 4f 52       ; "EXCHANGE   FOR"
&0ffe 1f 06 0e
&1001 62 5e 5b 5b 63 5e 5b 5b 64 5e 5b 5b 65 5e 5b 5b ; "1.  2.  3.  4.  5."
&1011 66 5e
&1013 0d

; enter_teleport_sound
;     envelope
&1014 04 01 f6 f1 ec 04 04 04 7e fa f3 dc 7e 5a
;     chan  vol   pitch dur
&1022 02 00 04 00 78 00 02 00

; enter_pyramid
&102a 20 00 0e JSR &0e00 ; prepare_teleport_or_pyramid_screen
&102d a2 da    LDX #&da
&102f a0 0f    LDY #&0f ; &0fda = cheops_pyramid_text
&1031 20 80 0a JSR &0a80 ; plot_text
; choose_random_pocket
&1034 20 40 64 JSR &6440 ; rnd                                      # Choose a pocket at random
&1037 29 03    AND #&03
&1039 a8       TAY
&103a b9 0f 00 LDA &000f,Y ; pockets
&103d f0 f5    BEQ &1034 ; choose_random_pocket                     # Check that it contains something
&103f 84 80    STY &80 ; pocket_to_swap
&1041 85 89    STA &89 ; pocket_contents                            # pocket_contents = pyramid_choices + 4
&1043 a9 03    LDA #&03
&1045 85 8e    STA &8e ; count
; choose_random_core_element
&1047 20 40 64 JSR &6440 ; rnd                                      # Choose a core element at random
&104a c9 09    CMP #&09
&104c b0 f9    BCS &1047 ; choose_random_core_element
&104e a8       TAY
&104f b9 17 00 LDA &0017,Y ; core_elements_required
&1052 c9 80    CMP #&80                                             # Top bit set if core element restored
&1054 b0 f1    BCS &1047 ; choose_random_core_element
&1056 a6 8e    LDX &8e ; count
&1058 29 1f    AND #&1f
&105a 95 85    STA &85,X ; pyramid_options
&105c c6 8e    DEC &8e ; count
&105e 10 e7    BPL &1047 ; choose_random_core_element
; plot_chosen_pocket
&1060 a2 ff    LDX #&ff                                             # White
&1062 a0 00    LDY #&00                                             # Overwrite screen
&1064 a9 90    LDA #&90
&1066 85 8e    STA &8e ; screen_address_low
&1068 a9 72    LDA #&72 ; &7290
&106a 85 8f    STA &8f ; screen_address_high
&106c a5 89    LDA &89 ; pocket_contents
&106e 20 b3 0b JSR &0bb3 ; plot_packed_two_colour_sprite            # Plot contents of chosen pocket
; plot_options
&1071 a9 18    LDA #&18
&1073 85 8e    STA &8e ; screen_address_low
&1075 a9 76    LDA #&76
&1077 85 8f    STA &8f ; screen_address_high
&1079 a9 00    LDA #&00
&107b 85 81    STA &81 ; option
; plot_options_loop
&107d a4 81    LDY &81 ; option
&107f b9 85 00 LDA &0085,Y ; pyramid_options
&1082 a2 ff    LDX #&ff                                             # White
&1084 a0 00    LDY #&00                                             # Overwrite screen
&1086 20 b3 0b JSR &0bb3 ; plot_packed_two_colour_sprite
&1089 38       SEC
&108a a5 8e    LDA &8e ; screen_address_low
&108c e9 d0    SBC #&d0
&108e 85 8e    STA &8e ; screen_address_low
&1090 a5 8f    LDA &8f ; screen_address_high
&1092 e9 01    SBC #&01
&1094 85 8f    STA &8f ; screen_address_high
&1096 e6 81    INC &81 ; option
&1098 a5 81    LDA &81 ; option
&109a c9 05    CMP #&05
&109c d0 df    BNE &107d ; plot_options_loop
&109e a9 0f    LDA #&0f ; Flush all buffers
&10a0 a2 00    LDX #&00
&10a2 20 f4 ff JSR &fff4 ; OSBYTE
; get_number
&10a5 20 e0 ff JSR &ffe0 ; OSRDCH
&10a8 38       SEC
&10a9 e9 31    SBC #&31 ; "1"
&10ab 90 f8    BCC &10a5 ; get_number
&10ad c9 05    CMP #&05
&10af b0 f4    BCS &10a5 ; get_number                               # Get a character between "1" and "5"
&10b1 48       PHA
&10b2 a8       TAY
&10b3 b9 85 00 LDA &0085,Y ; options
&10b6 a4 80    LDY &80 ; pocket_to_swap
&10b8 99 0f 00 STA &000f,Y ; pockets                                # Put the corresponding option in chosen pocket
&10bb 85 87    STA &87 ; chosen_option
&10bd 68       PLA
&10be 0a       ASL A
&10bf 0a       ASL A
&10c0 0a       ASL A
&10c1 0a       ASL A
&10c2 85 86    STA &86 ; option_screen_address_low
&10c4 0a       ASL A
&10c5 65 86    ADC &86 ; option_screen_address_low
&10c7 69 18    ADC #&18
&10c9 85 86    STA &86 ; option_screen_address_low
&10cb 20 17 0f JSR &0f17 ; play_error_sound
&10ce a9 32    LDA #&32
&10d0 85 88    STA &88 ; count
&10d2 a9 00    LDA #&00
&10d4 85 89    STA &89 ; colour
; flash_option
&10d6 a9 13    LDA #&13 ; Wait for v-sync
&10d8 20 f4 ff JSR &fff4 ; OSBYTE
&10db a5 86    LDA &86 ; option_screen_address_low
&10dd 85 8e    STA &8e ; screen_address_low
&10df a9 76    LDA #&76
&10e1 85 8f    STA &8f ; screen_address_high
&10e3 a5 89    LDA &89 ; colour
&10e5 49 ff    EOR #&ff
&10e7 85 89    STA &89 ; colour
&10e9 aa       TAX                                                  # Alternate between white and black
&10ea a0 00    LDY #&00                                             # Overwrite screen
&10ec a5 87    LDA &87 ; chosen_option
&10ee 20 b3 0b JSR &0bb3 ; plot_packed_two_colour_sprite            # Flash chosen option
&10f1 c6 88    DEC &88 ; count
&10f3 d0 e1    BNE &10d6 ; flash_option
&10f5 a8       TAY
&10f6 91 53    STA (&53),Y ; room_item_data_address                 # Remove chosen option from world
&10f8 c8       INY
&10f9 91 53    STA (&53),Y ; room_item_data_address
&10fb 60       RTS

# &10fc - &111b correspond to &14fc - &151b before the binary is decrypted.

; entry_point
&14fc a0 00    LDY #&00
&14fe 84 ff    STY &ff ; os_escape_pressed                          # Clear ESCAPE condition
; decrypt_74e8_to_75e7_loop                                         # Decrypt &74e8 - &75e7
&1500 b9 e8 74 LDA &74e8,Y ; decrypted_entry_point
&1503 49 ad    EOR #&ad
&1505 99 e8 74 STA &74e8,Y ; decrypted_entry_point
&1508 c8       INY
&1509 d0 f5    BNE &1500 ; decrypt_74e8_to_75e7_loop
; restore_0800_loop
&150b b9 00 11 LDA &1100,Y                                          # &0800 - &08ff was copied to &1100 - &11ff in loader
&150e 99 00 08 STA &0800,Y                                          # (OS sound workspace, buffers and envelopes)
&1511 c8       INY
&1512 d0 f7    BNE &150b ; restore_0800_loop
&1514 4c e8 74 JMP &74e8 ; decrypted_entry_point
; unused
&1517 3e 92 2d 8e 64                                                # Not meaningful encrypted or decrypted

# After decryption, this code is obscured, then overwritten by:

; &10fc  - &111b ula_palette_data

; start_game
&111c a0 09    LDY #&09
; reset_gates_loop
&111e b9 c3 61 LDA &61c3,Y ; gate_table
&1121 29 fd    AND #&fd                                             # Unset &02 to indicate gate is present
&1123 99 c3 61 STA &61c3,Y ; gate_table
&1126 88       DEY
&1127 88       DEY
&1128 10 f4    BPL &111e ; reset_gates_loop
&112a a9 80    LDA #&80
&112c 85 70    STA &70 ; player_screen_address_low
&112e a9 77    LDA #&77
&1130 85 71    STA &71 ; player_screen_address_high
&1132 a9 00    LDA #&00
&1134 85 46    STA &46 ; score
&1136 85 47    STA &47 ; score + 1
&1138 85 48    STA &48 ; score + 2
&113a a9 05    LDA #&05
&113c 85 49    STA &49 ; player_lives
&113e a0 00    LDY #&00
&1140 98       TYA
; wipe_item_data_loop
&1141 99 00 0c STA &0c00,Y ; item_data                              # Wipe &0c00 - &0dff
&1144 99 00 0d STA &0d00,Y ; item_data + &100
&1147 c8       INY
&1148 d0 f7    BNE &1141 ; wipe_item_data_loop
; reset_rooms_visited_loop
&114a 99 80 03 STA &0380,Y ; rooms_visited                          # Wipe &0380 - &03ff
&114d c8       INY
&114e 10 fa    BPL &114a ; reset_rooms_visited_loop
&1150 a0 07    LDY #&07
; reset_pockets_loop
&1152 98       TYA
&1153 29 04    AND #&04                                             # Set pockets to 0, previous_pockets to 4,
&1155 99 0f 00 STA &000f,Y ; pockets                                # forcing redraw
&1158 88       DEY
&1159 10 f7    BPL &1152 ; reset_pockets_loop
&115b 20 a0 20 JSR &20a0 ; wipe_subtiles
&115e a9 00    LDA #&00
&1160 85 0b    STA &0b ; adventure_score
&1162 85 0c    STA &0c ; adventure_score + 1
; place_items
&1164 85 88    STA &88 ; item_data_address_low
&1166 a9 0c    LDA #&0c ; &0c00 = item_data
&1168 85 89    STA &89 ; item_data_address_high
; place_items_loop
&116a 20 40 64 JSR &6440 ; rnd                                      # Pick a random room between &0000 and &01ff
&116d 85 8e    STA &8e ; items_used_address_low
&116f 20 40 64 JSR &6440 ; rnd
&1172 0a       ASL A
&1173 0a       ASL A
&1174 0a       ASL A
&1175 0a       ASL A
&1176 05 8e    ORA &8e ; items_used_address_low
&1178 85 8e    STA &8e ; items_used_address_low
&117a 20 40 64 JSR &6440 ; rnd
&117d 29 03    AND #&03
&117f 85 8a    STA &8a ; subtile_x
&1181 4a       LSR A
&1182 09 06    ORA #&06                                             # items_used_address is between &0600 and &07ff
&1184 85 8f    STA &8f ; items_used_address_high
&1186 a0 00    LDY #&00
&1188 b1 8e    LDA (&8e),Y ; items_used_address
&118a d0 de    BNE &116a ; place_items_loop                         # Is there already an item in this room?
&118c a9 01    LDA #&01
&118e 91 8e    STA (&8e),Y ; items_used_address
&1190 a5 8e    LDA &8e ; items_used_address_low
&1192 aa       TAX
&1193 18       CLC
&1194 69 c0    ADC #&c0
&1196 85 8e    STA &8e ; item_locations_address_low
&1198 a5 8f    LDA &8f ; items_used_address_high
&119a 69 31    ADC #&31 ; &31c0 = possible_item_locations - &600
&119c 85 8f    STA &8f ; item_locations_address_high
&119e b1 8e    LDA (&8e),Y ; item_locations_address                 # Get a byte of data for possible item location
&11a0 85 8d    STA &8d ; location_byte
&11a2 29 3f    AND #&3f                                             # Low six bits are tile to put item in
&11a4 c9 30    CMP #&30
&11a6 b0 c2    BCS &116a ; place_items_loop
&11a8 85 8c    STA &8c ; tile
&11aa 8a       TXA
&11ab 91 88    STA (&88),Y ; item_data_address                      # First byte of item data is room_low
&11ad a5 8d    LDA &8d ; location_byte
&11af 29 c0    AND #&c0                                             # Top two bits set where item can be placed vertically
&11b1 0a       ASL A
&11b2 2a       ROL A
&11b3 2a       ROL A
&11b4 69 01    ADC #&01
&11b6 85 8b    STA &8b ; subtile_y_limit
; choose_random_subtile_y
&11b8 20 40 64 JSR &6440 ; rnd
&11bb 29 03    AND #&03
&11bd c5 8b    CMP &8b ; subtile_y_limit
&11bf b0 f7    BCS &11b8 ; choose_random_subtile
&11c1 65 8c    ADC &8c ; tile
&11c3 46 8a    LSR &8a ; subtile_x
&11c5 66 8a    ROR &8a ; subtile_x
&11c7 66 8a    ROR &8a ; subtile_x
&11c9 05 8a    ORA &8a ; subtile_x
&11cb a0 01    LDY #&01
&11cd 91 88    STA (&88),Y ; item_data_address                      # Second byte of item data is room_high and position
&11cf e6 88    INC &88 ; item_data_address_low
&11d1 e6 88    INC &88 ; item_data_address_low
&11d3 d0 95    BNE &116a ; initialise_items_loop
&11d5 e6 89    INC &89 ; item_data_address_high
&11d7 a5 89    LDA &89 ; item_data_address_high
&11d9 c9 0e    CMP #&0e
&11db d0 8d    BNE &116a ; initialise_items_loop
; initialise_player
&11dd a9 00    LDA #&00
&11df 85 72    STA &72 ; player_sprite
&11e1 85 22    STA &22 ; player_facing                              # Zero to indicate facing left
&11e3 85 9f    STA &9f ; core_elements_placed
&11e5 a9 01    LDA #&01 ; FIRE_LEFT
&11e7 85 76    STA &76 ; player_on_hopper                           # Non-zero to indicate player not on hopper
&11e9 85 7a    STA &7a ; fire_direction
&11eb a0 0b    LDY #&0b
; reset_core_elements_required_loop
&11ed 98       TYA
&11ee 99 0c 00 STA &000c,Y ; core_elements_required - &b            # Wipe &0017 - &001f
&11f1 c8       INY
&11f2 c0 14    CPY #&14
&11f4 d0 f7    BNE &11ed ; reset_core_elements_required_loop
; choose_core_elements
&11f6 a9 04    LDA #&04                                             # Change four core elements to non-structural types
&11f8 85 8e    STA &8e ; count
; choose_core_elements_loop
&11fa 20 40 64 JSR &6440 ; rnd                                      # Pick a random non-structural type of element
&11fd c9 0a    CMP #&0a
&11ff b0 f9    BCS &11fa ; choose_core_elements_loop
&1201 69 14    ADC #&14 ; ITEM_CORE_CHIP_1
&1203 a0 08    LDY #&08
; check_if_element_already_used_loop
&1205 d9 17 00 CMP &0017,Y ; core_elements_required
&1208 f0 f0    BEQ &11fa ; choose_core_elements_loop                # Has this element already been used?
&120a 88       DEY
&120b 10 f8    BPL &1205 ; check_if_element_already_used_loop
&120d 48       PHA
; choose_random_position
&120e 20 40 64 JSR &6440 ; rnd                                      # If not, pick a random position to put it in
&1211 c9 09    CMP #&09
&1213 b0 f9    BCS &120e ; choose_random_position
&1215 aa       TAX
&1216 b5 17    LDA &17,X ; core_elements_required
&1218 c9 14    CMP #&14 ; ITEM_CORE_CHIP_1                          # Is there already a non-structural element there?
&121a b0 f2    BCS &120e ; choose_random_position
&121c 68       PLA
&121d 95 17    STA &17,X ; core_elements_required                   # If not, change the core element
&121f c6 8e    DEC &8e ; count
&1221 10 d7    BPL &11fa ; change_core_elements_loop
; place_core_elements
&1223 a9 00    LDA #&00
&1225 85 8c    STA &8c ; possible_locations_offset
&1227 85 8d    STA &8d ; data_offset
&1229 85 8b    STA &8b ; core_element_to_consider 
; place_core_elements_loop
&122b 20 40 64 JSR &6440 ; rnd
&122e 29 02    AND #&02
&1230 18       CLC
&1231 65 8c    ADC &8c ; possible_locations_offset
&1233 a8       TAY
&1234 b9 cd 61 LDA &61cd,Y ; possible_core_element_locations
&1237 a6 8d    LDX &8d ; data_offset
&1239 9d 28 05 STA &0528,X ; core_elements_data + 0                 # Set room_low
&123c b9 ce 61 LDA &61ce,Y ; possible_core_element_locations + 1
&123f 48       PHA
&1240 48       PHA
&1241 29 01    AND #&01
&1243 9d 29 05 STA &0529,X ; core_elements_data + 1                 # Set room_high
&1246 68       PLA
&1247 0a       ASL A
&1248 0a       ASL A
&1249 0a       ASL A
&124a 0a       ASL A
&124b 29 e0    AND #&e0
&124d 09 08    ORA #&08
&124f 1d 29 05 ORA &0529,X ; core_elements_data + 1
&1252 9d 29 05 STA &0529,X ; core_elements_data + 1                 # Set screen_address_low
&1255 68       PLA
&1256 29 70    AND #&70
&1258 4a       LSR A
&1259 4a       LSR A
&125a 4a       LSR A
&125b 85 8e    STA &8e ; tmp
&125d 4a       LSR A
&125e 65 8e    ADC &8e ; tmp
&1260 69 6e    ADC #&6e
&1262 9d 2a 05 STA &052a,X ; core_elements_data + 2                 # Set screen_address_high
&1265 a5 8b    LDA &8b ; core_element_to_consider
&1267 c9 0b    CMP #&0b
&1269 b0 0a    BCS &1275 ; use_random_sprite
; use_required_sprite
&126b a8       TAY
&126c b9 15 00 LDA &0015,Y ; core_elements_required - 2
&126f 9d 2b 05 STA &052b,X ; core_elements_data + 3                 # Set sprite
&1272 4c 88 12 JMP &1288 ; consider_next_core_element
; use_random_sprite
&1275 20 40 64 JSR &6440 ; rnd
&1278 a5 9b    LDA &9b ; rnd_2
&127a 29 1f    AND #&1f
&127c c9 13    CMP #&13 ; ITEM_CORE_EXTINGUISHER - &0b
&127e b0 f5    BCS &1275 ; use_random_sprite                        # Choose a random type between &13 and &1d
&1280 18       CLC
&1281 69 0b    ADC #&0b ; ITEM_CORE_TOP_LEFT
&1283 a6 8d    LDX &8d ; data_offset
&1285 9d 2b 05 STA &052b,X ; core_elements_data + 3                 # Set sprite
; consider_next_core_element
&1288 18       CLC
&1289 a5 8c    LDA &8c ; possible_locations_offset
&128b 69 04    ADC #&04
&128d 85 8c    STA &8c ; possible_locations_offset
&128f a5 8d    LDA &8d ; data_offset
&1291 69 04    ADC #&04
&1293 85 8d    STA &8d ; data_offset
&1295 e6 8b    INC &8b ; core_element_to_consider
&1297 a5 8b    LDA &8b ; core_element_to_consider
&1299 c9 01    CMP #&01
&129b f0 04    BEQ &12a1 ; is_pass_or_key
&129d c9 03    CMP #&03
&129f d0 11    BNE &12b2 ; not_pass_or_key
; is_pass_or_key
&12a1 38       SEC                                                  # ITEM_PASS and ITEM_KEY can go in one of four rooms
&12a2 a5 8d    LDA &8d ; data_offset
&12a4 e9 04    SBC #&04
&12a6 85 8d    STA &8d ; data_offset
&12a8 20 40 64 JSR &6440 ; rnd
&12ab 29 01    AND #&01                                             # 1 in 2 chance to use second set of two rooms
&12ad f0 d9    BEQ &1288 ; consider_next_core_element
; to_place_core_elements_loop
&12af 4c 2b 12 JMP &122b ; place_core_elements_loop
; not_pass_or_key
&12b2 a5 8b    LDA &8b ; core_element_to_consider
&12b4 c9 16    CMP #&16
&12b6 d0 f7    BNE &12af ; place_core_elements_loop
&12b8 a9 09    LDA #&09 ; ITEM_PASS
&12ba 8d 2b 05 STA &052b ; core_elements_data + 3                   # Set core element 0 sprite
&12bd a9 0a    LDA #&0a ; ITEM_KEY
&12bf 8d 2f 05 STA &052f ; core_elements_data + 7                   # Set core element 1 sprite
&12c2 a9 08    LDA #&08
&12c4 85 7e    STA &7e ; player_room_low
&12c6 a9 00    LDA #&00
&12c8 85 7f    STA &7f ; player_room_high
&12ca 78       SEI
&12cb 85 23    STA &23 ; game_time_countdown
&12cd e6 23    INC &23 ; game_time_countdown
&12cf 85 24    STA &24 ; game_time_low
&12d1 85 25    STA &25 ; game_time_high
&12d3 58       CLI
&12d4 85 9e    STA &9e ; player_in_pipe
&12d6 85 35    STA &35 ; previous_player_energy_high
&12d8 85 37    STA &37 ; previous_player_fuel_high
&12da 85 39    STA &39 ; previous_player_ammunition_high
&12dc a9 0f    LDA #&0f
&12de 85 31    STA &31 ; previous_score + 1
&12e0 a9 10    LDA #&10
&12e2 85 3f    STA &3f ; player_ammunition_high
&12e4 a9 06    LDA #&06
&12e6 85 3d    STA &3d ; player_fuel_high
&12e8 a9 ff    LDA #&ff
&12ea 85 3e    STA &3e ; player_ammunition_low
&12ec 20 60 25 JSR &2560 ; store_player_entry_position
; start_new_life
&12ef a5 5a    LDA &5a ; player_entry_screen_address_low
&12f1 85 70    STA &70 ; player_screen_address_low
&12f3 a5 5b    LDA &5b ; player_entry_screen_address_high
&12f5 85 71    STA &71 ; player_screen_address_high
&12f7 a5 5c    LDA &5c ; player_entry_sprite
&12f9 85 72    STA &72 ; player_sprite
&12fb a5 5d    LDA &5d ; player_entry_on_platform
&12fd 85 76    STA &76 ; player_on_hopper
&12ff f8       SED
&1300 38       SEC
&1301 a5 49    LDA &49 ; player_lives
&1303 e9 01    SBC #&01
&1305 85 49    STA &49 ; player_lives
&1307 d8       CLD
&1308 b0 01    BCS &130b ; player_is_still_alive
&130a 60       RTS                                                  # Leave with carry clear to indicate game not completed
; player_is_still_alive
&130b a9 10    LDA #&10
&130d 85 3b    STA &3b ; player_energy_high
&130f a5 3d    LDA &3d ; player_fuel_high
&1311 09 01    ORA #&01
&1313 85 3d    STA &3d ; player_fuel_high
&1315 a9 ff    LDA #&ff
&1317 85 3c    STA &3c ; player_fuel_low
&1319 85 3a    STA &3a ; player_energy_low
; enter_room_after_pyramid
&131b a9 03    LDA #&03
&131d 85 29    STA &29 ; player_room_history + 3                    # Remove enemies from nearby rooms
&131f 85 27    STA &27 ; player_room_history + 1
; enter_room
&1321 20 24 35 JSR &3524 ; flush_buffers
&1324 20 60 25 JSR &2560 ; store_player_entry_position
&1327 a5 80    LDA &80 ; player_action
&1329 48       PHA
&132a a0 2f    LDY #&2f
; swap_enemies_loop
&132c b9 88 01 LDA &0188,Y ; enemies_data
&132f aa       TAX
&1330 b9 58 01 LDA &0158,Y ; previous_enemies_data
&1333 99 88 01 STA &0188,Y ; enemies_data
&1336 8a       TXA
&1337 99 58 01 STA &0158,Y ; previous_enemies_data
&133a 88       DEY
&133b 10 ef    BPL &132c ; swap_enemies_loop
&133d 20 a0 20 JSR &20a0 ; wipe_subtiles
; mark_room_as_visited
&1340 a5 7f    LDA &7f ; player_room_high
&1342 4a       LSR A
&1343 a5 7e    LDA &7e ; player_room_low
&1345 6a       ROR A
&1346 4a       LSR A
&1347 4a       LSR A
&1348 a8       TAY
&1349 a9 00    LDA #&00
&134b 85 8f    STA &8f ; bit
&134d a5 7e    LDA &7e ; player_room_low
&134f 29 07    AND #&07
&1351 aa       TAX
&1352 38       SEC
; calculate_bit_loop
&1353 26 8f    ROL &8f ; bit
&1355 ca       DEX
&1356 10 fb    BPL &1353 ; calculate_bit_loop
&1358 b9 80 03 LDA &0380,Y ; rooms_visited
&135b 25 8f    AND &8f ; bit
&135d d0 1e    BNE &137d ; room_already_visisted
&135f b9 80 03 LDA &0380,Y ; rooms_visited
&1362 05 8f    ORA &8f ; bit
&1364 99 80 03 STA &0380,Y ; rooms_visited
&1367 a0 02    LDY #&02                                             # Score 250 for visiting an unvisited room
&1369 a2 50    LDX #&50
&136b 20 4f 35 JSR &354f ; increase_score
&136e 18       CLC
&136f a5 0b    LDA &0b ; adventure_score
&1371 69 32    ADC #&32                                             # Score 50/256 % for visiting an unvisited room
&1373 85 0b    STA &0b ; adventure_score
&1375 a5 0c    LDA &0c ; adventure_score + 1
&1377 f8       SED
&1378 69 00    ADC #&00
&137a d8       CLD
&137b 85 0c    STA &0c ; adventure_score + 1
; room_already_visisted
&137d a6 7e    LDX &7e ; player_room_low
&137f a4 7f    LDY &7f ; player_room_high
&1381 20 f0 25 JSR &25f0 ; plot_room
&1384 20 71 25 JSR &2571 ; calculate_player_group_address_and_hopper_sprite
&1387 a6 70    LDX &70 ; player_screen_address_low
&1389 a4 71    LDY &71 ; player_screen_address_high
&138b 20 2f 25 JSR &252f ; calculate_below_subtile_address_from_screen_address
&138e 86 74    STX &74 ; below_player_subtile_address_low
&1390 84 75    STY &75 ; below_player_subtile_address_high
&1392 a9 00    LDA #&00
&1394 85 73    STA &73 ; falling_time
&1396 68       PLA ; player_action
&1397 85 80    STA &80 ; player_action
&1399 20 d4 23 JSR &23d4 ; plot_status
&139c a5 2e    LDA &2e ; new_enemies_cooldown                       # Store room's enemy state in history
&139e 85 2c    STA &2c ; new_enemies_cooldown_history + 2
&13a0 a5 2f    LDA &2f ; new_enemies_needed
&13a2 85 2d    STA &2d ; new_enemies_needed_history + 2
&13a4 a5 26    LDA &26 ; player_room_history
&13a6 c5 7e    CMP &7e ; player_room_low
&13a8 d0 11    BNE &13bb ; not_previous_room                        # Is this the previous room visited?
&13aa a5 27    LDA &27 ; player_room_history + 1
&13ac c5 7f    CMP &7f ; player_room_high
&13ae d0 0b    BNE &13bb ; not_previous_room
&13b0 a5 2a    LDA &2a ; new_enemies_cooldown_history               # If so, use previous enemies
&13b2 85 2e    STA &2e ; new_enemies_cooldown
&13b4 a5 2b    LDA &2b ; new_enemies_needed_history
&13b6 85 2f    STA &2f ; new_enemies_needed
&13b8 4c 30 14 JMP &1430 ; skip_initialising_enemies
; not_previous_room                                                 # Otherwise,
&13bb 20 40 64 JSR &6440 ; rnd
&13be 09 10    ORA #&10                                             # Between &10 and &1f frames before new enemies appear
&13c0 85 2e    STA &2e ; new_enemies_cooldown
&13c2 20 40 64 JSR &6440 ; rnd
&13c5 29 01    AND #&01
&13c7 09 02    ORA #&02                                             # 3 or 4 enemies
&13c9 85 2f    STA &2f ; new_enemies_needed
&13cb a0 2f    LDY #&2f
&13cd a9 00    LDA #&00
; wipe_enemies_data_loop                                            # Wipe previous enemies
&13cf 99 88 01 STA &0188,Y ; enemies_data
&13d2 88       DEY
&13d3 10 fa    BPL &13cf ; wipe_enemies_data_loop
&13d5 a5 7f    LDA &7f ; player_room_high
&13d7 f0 57    BEQ &1430 ; skip_initialising_enemies
; check_room_for_patrolling_droids
&13d9 a9 26    LDA #&26
&13db 85 8e    STA &8e ; special_rooms_offset
; consider_next_room
&13dd c6 8e    DEC &8e ; special_rooms_offset
&13df c6 8e    DEC &8e ; special_rooms_offset
&13e1 30 4d    BMI &1430 ; skip_initialising_enemies
&13e3 a4 8e    LDY &8e ; special_rooms_offset
&13e5 b9 85 61 LDA &6185,Y ; rooms_with_patrolling_droids           # Does this room have patrolling droids?
&13e8 c5 7e    CMP &7e ; player_room_low
&13ea d0 f1    BNE &13dd ; consider_next_room
&13ec b9 86 61 LDA &6186,Y ; rooms_with_patrolling_droids + 1
&13ef 48       PHA
&13f0 29 f8    AND #&f8
&13f2 8d 32 23 STA &2332 ; patrolling_droid_data                    # Set enemies_screen_address_low
&13f5 68       PLA
&13f6 29 03    AND #&03
&13f8 85 8e    STA &8e ; patrolling_droids_needed
&13fa a0 00    LDY #&00
; initialise_patrolling_droids_loop
&13fc 84 8f    STY &8f ; enemy_offset
&13fe 20 40 64 JSR &6440 ; rnd                                      # Patrolling droids have random speed
&1401 69 08    ADC #&08
&1403 8d 36 23 STA &2336 ; patrolling_droid_data + 4                # Set enemies_inertia
&1406 20 40 64 JSR &6440 ; rnd                                      # Patrolling droids have random direction
&1409 29 01    AND #&01
&140b aa       TAX
&140c bd 3e 23 LDA &233e,X ; patrolling_droid_direction_table
&140f 8d 35 23 STA &2335 ; patrolling_droid_data + 5                # Set enemies_direction
&1412 a4 8f    LDY &8f ; enemy_offset
&1414 a2 00    LDX #&00
; copy_patrolling_droid_data_loop
&1416 bd 32 23 LDA &2332,X ; patrolling_droid_data
&1419 99 88 01 STA &0188,Y ; enemies_data
&141c e8       INX
&141d c8       INY
&141e e0 0c    CPX #&0c
&1420 90 f4    BCC &1416 ; copy_patrolling_droid_data_loop
&1422 ad 32 23 LDA &2332 ; patrolling_droid_data                    # Increase enemies_screen_address_low
&1425 69 1f    ADC #&1f
&1427 8d 32 23 STA &2332 ; patrolling_droid_data
&142a c6 2f    DEC &2f ; new_enemies_needed
&142c c6 8e    DEC &8e ; patrolling_droids_needed
&142e 10 cc    BPL &13fc ; initialise_patrolling_droids_loop
; skip_initialising_enemies
&1430 a9 01    LDA #&01
&1432 85 0d    STA &0d ; gate_screen_address_low
&1434 20 b6 2e JSR &2eb6 ; update_enemies                           # Unplot enemies
&1437 20 66 23 JSR &2366 ; plot_gates
&143a a0 00    LDY #&00
; rotate_player_room_and_enemy_history_loop
&143c b9 28 00 LDA &0028,Y ; player_room_history + 2                # Move &0028 - &002f to &0026 - &002d
&143f 99 26 00 STA &0026,Y ; player_room_history                    # i.e. rotate player_room_history
&1442 c8       INY                                                  #      new_enemies_cooldown_history
&1443 c0 08    CPY #&08                                             #  and new_enemies_needed_history
&1445 d0 f5    BNE &143c ; rotate_player_room_and_enemy_history_loop
&1447 a5 7e    LDA &7e ; player_room_low                            # Store current room in room history
&1449 85 28    STA &28 ; player_room_history + 2
&144b a5 7f    LDA &7f ; player_room_high
&144d 85 29    STA &29 ; player_room_history + 3
&144f a5 7f    LDA &7f ; player_room_high
&1451 d0 0e    BNE &1461 ; is_regular_room
&1453 a5 7e    LDA &7e ; player_room_low
&1455 c9 c7    CMP #&c7                                             # Is the core room? (&0c7)
&1457 f0 0b    BEQ &1464 ; is_core_room                             
&1459 c9 c6    CMP #&c6                                             # or the room to the left of the core room? (&0c6)
&145b d0 04    BNE &1461 ; is_regular_room
; is_left_of_core_room
&145d a9 ff    LDA #&ff                                             # Stop enemies spawning in room left of core room
&145f 85 2e    STA &2e ; new_enemies_cooldown
; is_regular_room
&1461 4c ec 15 JMP &15ec ; not_core_room
; is_core_room
&1464 a9 01    LDA #&01                                             # Unplot enemies, don't update
&1466 20 b6 2e JSR &2eb6 ; update_enemies
&1469 a9 6d    LDA #&6d
&146b 85 8e    STA &8e ; subtile_address_low
&146d a9 06    LDA #&06 ; &066d = room_subtiles + &20 * 6 + &d      # Move four subtiles down, thirteen across
&146f 85 8f    STA &8f ; subtile_address_high
&1471 a2 06    LDX #&06
; set_subtiles_column_loop
&1473 a0 05    LDY #&05
; set_subtiles_row_loop
&1475 a9 18    LDA #&18 ; SUBTILE_NO_ENEMIES | SUBTILE_NO_PLAYER
&1477 91 8e    STA (&8e),Y ; subtile_address                        # Set core area to be impassable
&1479 88       DEY
&147a 10 f9    BPL &1475 ; set_subtiles_row_loop
&147c 18       CLC
&147d a5 8e    LDA &8e ; subtile_address_low
&147f 69 20    ADC #&20
&1481 85 8e    STA &8e ; subtile_address_low
&1483 90 02    BCC &1487 ; skip_overflow
&1485 e6 8f    INC &8f ; subtile_address_high
; skip_overflow
&1487 ca       DEX
&1488 d0 e9    BNE &1473 ; set_subtiles_column_loop
&148a 20 63 35 JSR &3563 ; set_core_element_colours
&148d a9 00    LDA #&00
&148f a2 73    LDX #&73 ; &7300
&1491 20 87 35 JSR &3587 ; plot_full_core_array                     # Plot core array
&1494 20 00 7f JSR &7f00 ; to_set_screen_colours
&1497 a9 00    LDA #&00
&1499 85 84    STA &84 ; pocket_to_consider                         # For each pocket,
; check_pockets_for_core_elements_pocket_loop
&149b a4 84    LDY &84 ; pocket_to_consider
&149d b9 0f 00 LDA &000f,Y ; pockets
&14a0 a0 08    LDY #&08
; check_pockets_for_core_elements_element_loop
&14a2 d9 17 00 CMP &0017,Y ; core_elements_required                 # does it contain a required core element?
&14a5 f0 06    BEQ &14ad ; pocket_contains_required_core_element
&14a7 88       DEY
&14a8 10 f8    BPL &14a2 ; check_pockets_for_core_elements_element_loop
&14aa 4c 06 15 JMP &1506 ; consider_next_pocket
; pocket_contains_required_core_element
&14ad 85 83    STA &83 ; core_element_type
&14af 84 85    STY &85 ; core_element_offset
&14b1 85 81    STA &81 ; core_element_for_pocket
&14b3 a9 0f    LDA #&0f
&14b5 85 86    STA &86 ; count
&14b7 b9 75 35 LDA &3575,Y ; initial_core_element_colours
&14ba 8d 9e 20 STA &209e ; core_element_flash_colours               # Set first colour of flash to be colour 1 or 2
; flash_restored_core_element_loop
&14bd a5 86    LDA &86 ; count
&14bf 29 01    AND #&01
&14c1 aa       TAX
&14c2 bd 9e 20 LDA &209e,X ; core_element_flash_colours             # Alternate between first flash colour and white
&14c5 a4 85    LDY &85 ; core_element_offset
&14c7 99 f7 0b STA &0bf7,Y ; core_elements_colours
&14ca a4 84    LDY &84 ; pocket_to_consider
&14cc a5 81    LDA &81 ; core_element_for_pocket
&14ce 99 0f 00 STA &000f,Y ; pockets
&14d1 45 83    EOR &83 ; core_element_type                          # Alternate pocket between core element and empty
&14d3 85 81    STA &81 ; core_element_for_pocket
&14d5 a2 34    LDX #&34
&14d7 a0 60    LDY #&60 ; &6034 = core_element_from_pocket_sound
&14d9 20 3d 35 JSR &353d ; play_sound
&14dc a9 00    LDA #&00
&14de a2 73    LDX #&73
&14e0 20 93 35 JSR &3593 ; plot_partial_core_array
&14e3 20 d4 23 JSR &23d4 ; plot_status
&14e6 a9 07    LDA #&07
&14e8 20 42 35 JSR &3542 ; wait_for_a_frames
&14eb c6 86    DEC &86 ; count
&14ed 10 ce    BPL &14bd ; flash_restored_core_element_loop
&14ef a5 85    LDA &85 ; core_element_offset
&14f1 a8       TAY
&14f2 18       CLC
&14f3 69 8b    ADC #&8b                                             # Set top bit to indicate core element has been
&14f5 99 17 00 STA &0017,Y ; core_elements_required                 # restore, use structural element for position
&14f8 a9 ff    LDA #&ff                                             # Set restored core element to be white in array
&14fa 99 f7 0b STA &0bf7,Y ; core_elements_colours
&14fd e6 9f    INC &9f ; core_elements_placed
&14ff a5 9f    LDA &9f ; core_elements_placed
&1501 c9 09    CMP #&09                                             # Have all nine core elements been restored? If so,
&1503 90 01    BCC &1506 ; consider_next_pocket
&1505 60       RTS                                                  # Leave with carry set to indicate game completed
; consider_next_pocket
&1506 e6 84    INC &84 ; pocket_to_consider
&1508 a5 84    LDA &84 ; pocket_to_consider
&150a c9 04    CMP #&04
&150c d0 8d    BNE &149b ; check_pockets_for_core_elements_pocket_loop
&150e a0 2f    LDY #&2f
; copy_core_room_materialisation_data_loop
&1510 b9 02 23 LDA &2302,Y ; core_room_materialisation_data         # Use core room materialisations for enemies
&1513 99 88 01 STA &0188,Y ; enemies_screen_address_low
&1516 88       DEY
&1517 10 f7    BPL &1510 ; copy_core_room_materialisation_data_loop
&1519 a9 08    LDA #&08
&151b 85 8e    STA &8e ; count
; randomise_materialisation_positions_loop
&151d 20 40 64 JSR &6440 ; rnd                                      # Choose a random multiple of 12 for enemy offset
&1520 a5 9b    LDA &9b ; rnd_2
&1522 29 18    AND #&18
&1524 85 8f    STA &8f ; random_enemy_offset
&1526 4a       LSR A
&1527 65 8f    ADC &8f ; random_enemy_offset
&1529 a8       TAY
&152a b9 88 01 LDA &0188,Y ; enemies_screen_address_low
&152d 49 08    EOR #&08                                             # Move enemy by 4 pixels left or right
&152f 99 88 01 STA &0188,Y ; enemies_screen_address_low
&1532 20 40 64 JSR &6440 ; rnd                                      # Choose a random multiple of 12 for enemy offset
&1535 a5 9b    LDA &9b ; rnd_2
&1537 29 18    AND #&18
&1539 85 8f    STA &8f ; random_enemy_offset
&153b 4a       LSR A
&153c 65 8f    ADC &8f ; random_enemy_offset
&153e a8       TAY
&153f b9 89 01 LDA &0189,Y ; enemies_screen_address_high
&1542 49 01    EOR #&01                                             # Move enemy by 8 pixels up or down
&1544 99 89 01 STA &0189,Y ; enemies_screen_address_high
&1547 c6 8e    DEC &8e ; count
&1549 d0 d2    BNE &151d ; randomise_materialisation_positions_loop
&154b a5 9f    LDA &9f ; core_elements_placed
&154d 85 70    STA &70 ; unused                                     # Unnecessary code
&154f 38       SEC
&1550 a9 08    LDA #&08
&1552 e5 9f    SBC &9f ; core_elements_placed                       # Add one materialisation for every two core elements
&1554 4a       LSR A                                                # restored
; remove_enemies_loop
&1555 85 8e    STA &8e ; count
&1557 c6 8e    DEC &8e ; count
&1559 30 1f    BMI &157a ; skip_removing_enemies
; choose_random_enemy
&155b 20 40 64 JSR &6440 ; rnd                                      # Choose a random multiple of 12 for enemy offset
&155e a5 9b    LDA &9b ; rnd_2
&1560 29 18    AND #&18
&1562 85 8f    STA &8f ; random_enemy_offset
&1564 4a       LSR A
&1565 65 8f    ADC &8f ; random_enemy_offset
&1567 aa       TAX
&1568 bd 89 01 LDA &0189,X ; enemies_screen_address_high            # Is there an enemy in this slot?
&156b f0 ee    BEQ &155b ; choose_random_enemy                      # If not, choose another slot
&156d a9 00    LDA #&00
&156f a0 0c    LDY #&0c
; wipe_enemy_loop
&1571 9d 88 01 STA &0188,X ; enemies_screen_address_low
&1574 e8       INX
&1575 88       DEY
&1576 d0 f9    BNE &1571 ; wipe_enemy_loop
&1578 f0 dd    BEQ &1557 ; remove_enemies_loop
; skip_removing_enemies
&157a a9 01    LDA #&01                                             # Unplot enemies, don't update
&157c 20 b6 2e JSR &2eb6 ; update_enemies
&157f a9 64    LDA #&64
; core_room_loop
&1581 48       PHA ; frames
; choose_random_colour
&1582 20 40 64 JSR &6440 ; rnd                                      # Choose a random colour
&1585 c9 05    CMP #&05                                             # from green, yellow, blue, magenta or cyan
&1587 b0 f9    BCS &1582 ; choose_random_colour
&1589 69 02    ADC #&02
&158b 85 95    STA &95 ; palette + 5                                # Set colour two of bottom section
&158d a9 02    LDA #&02
; core_room_inner_loop
&158f 48       PHA ; inner_frames
&1590 a9 13    LDA #&13 ; Wait for v-sync
&1592 20 f4 ff JSR &fff4 ; OSBYTE
&1595 ad 3e 60 LDA &603e ; restored_core_element_sound + 2
&1598 49 f1    EOR #&f1                                             # Alternate volume between silent and full
&159a 8d 3e 60 STA &603e ; restored_core_element_sound + 2
&159d a2 3c    LDX #&3c
&159f a0 60    LDY #&60 ; &603c = restored_core_element_sound
&15a1 20 3d 35 JSR &353d ; play_sound
&15a4 a9 00    LDA #&00                                             # Update and replot enemies
&15a6 20 b6 2e JSR &2eb6 ; update_enemies
&15a9 68       PLA ; inner_frames
&15aa 38       SEC
&15ab e9 01    SBC #&01
&15ad d0 e0    BNE &158f ; core_room_inner_loop
&15af 20 00 7f JSR &7f00 ; to_set_screen_colours
&15b2 a9 00    LDA #&00
&15b4 a2 73    LDX #&73
&15b6 20 93 35 JSR &3593 ; plot_partial_core_array
&15b9 a9 08    LDA #&08
&15bb 85 8e    STA &8e ; count
; randomise_colours_of_unrestored_core_elements_loop
&15bd 20 40 64 JSR &6440 ; rnd                                      # Choose colour 1 or 2 at random
&15c0 a2 f0    LDX #&f0
&15c2 29 01    AND #&01
&15c4 d0 02    BNE &15c8 ; use_colour_2
&15c6 a2 0f    LDX #&0f
; use_colour_2
&15c8 a4 8e    LDY &8e ; count
&15ca 8a       TXA
&15cb b6 17    LDX &17,Y ; core_elements_required
&15cd 30 03    BMI &15d2 ; skip_element                             # Has this core element been restored?
&15cf 99 f7 0b STA &0bf7,Y ; core_elements_colours                  # If not, set its colour
; skip_element
&15d2 c6 8e    DEC &8e ; count
&15d4 10 e7    BPL &15bd ; randomise_colours_of_unrestored_core_elements_loop
&15d6 68       PLA ; frames
&15d7 38       SEC
&15d8 e9 01    SBC #&01
&15da f0 03    BEQ &15df ; finished_in_core_room
&15dc 4c 81 15 JMP &1581 ; core_room_loop
; finished_in_core_room
&15df c6 7e    DEC &7e ; player_room_low                            # Return player to room left of core room
&15e1 a9 03    LDA #&03                                             # Prevent any falling or walking sound
&15e3 85 73    STA &73 ; falling_time
&15e5 a9 e8    LDA #&e8                                             # Put player at right edge of room
&15e7 85 70    STA &70 ; player_screen_address_low
&15e9 4c 21 13 JMP &1321 ; enter_room
; not_core_room
&15ec 20 d9 20 JSR &20d9 ; replot_player
&15ef 20 00 7f JSR &7f00 ; to_set_screen_colours
&15f2 a9 00    LDA #&00
&15f4 85 77    STA &77 ; player_on_hopper_pad                       # Zero to indicate player not on hopper pad
&15f6 85 7b    STA &7b ; fire_hit_something
&15f8 85 7c    STA &7c ; fire_screen_address_low
&15fa 85 7d    STA &7d ; fire_screen_address_high
&15fc 85 45    STA &45 ; player_walking_direction
&15fe ad 40 02 LDA &0240 ; os_cfs_timeout_counter
&1601 85 50    STA &50 ; previous_cfs_timeout_counter
; main_game_loop
&1603 a5 76    LDA &76 ; player_on_hopper
&1605 85 21    STA &21 ; previous_player_on_hopper
&1607 20 54 25 JSR &2554 ; calculate_below_player_subtile_address
&160a a5 80    LDA &80 ; player_action
&160c 85 81    STA &81 ; previous_player_action
&160e 29 0f    AND #&0f ; PLAYER_LEFT | PLAYER_RIGHT | PLAYER_UP | PLAYER_DOWN
&1610 f0 0e    BEQ &1620 ; skip_setting_fire_direction
&1612 c9 0f    CMP #&0f ; PLAYER_LEFT | PLAYER_RIGHT | PLAYER_UP | PLAYER_DOWN
&1614 f0 0a    BEQ &1620 ; skip_setting_fire_direction
&1616 c9 03    CMP #&03 ; PLAYER_LEFT | PLAYER_RIGHT
&1618 f0 06    BEQ &1620 ; skip_setting_fire_direction
&161a c9 0c    CMP #&0c ; PLAYER_UP | PLAYER_DOWN
&161c f0 02    BEQ &1620 ; skip_setting_fire_direction
&161e 85 79    STA &79 ; player_fire_direction
; skip_setting_fire_direction
&1620 a9 00    LDA #&00
&1622 85 80    STA &80 ; player_action
&1624 a4 0a    LDY &0a ; input_method
&1626 c0 0a    CPY #&0a
&1628 90 3c    BCC &1666 ; check_keys
; check_joystick
&162a a9 80    LDA #&80 ; Read I/O device
&162c a2 01    LDX #&01 ; Analogue channel 1
&162e 20 f4 ff JSR &fff4 ; OSBYTE
&1631 a2 00    LDX #&00
&1633 c0 38    CPY #&38
&1635 b0 02    BCS &1639 ; joystick_not_right
&1637 a2 02    LDX #&02 ; PLAYER_RIGHT
; joystick_not_right
&1639 c0 c8    CPY #&c8
&163b 90 02    BCC &163f ; joystick_not_left
&163d a2 01    LDX #&01 ; PLAYER_LEFT
; joystick_not_left
&163f 86 80    STX &80 ; player_action
&1641 a9 80    LDA #&80 ; Read I/O device
&1643 a2 02    LDX #&02 ; Analogue channel 2
&1645 20 f4 ff JSR &fff4 ; OSBYTE
&1648 a5 80    LDA &80 ; player_action
&164a c0 38    CPY #&38
&164c b0 02    BCS &1650 ; joystick_not_down
&164e 09 08    ORA #&08 ; PLAYER_DOWN
; joystick_not_down
&1650 c0 c8    CPY #&c8
&1652 90 02    BCC &1656 ; joystick_not_up
&1654 09 04    ORA #&04 ; PLAYER_UP
; joystick_not_up
&1656 85 80    STA &80 ; player_action
&1658 a9 80    LDA #&80 ; Read I/O device
&165a a2 00    LDX #&00 ; buttons
&165c 20 f4 ff JSR &fff4 ; OSBYTE
&165f 8a       TXA
&1660 29 03    AND #&03
&1662 f0 4b    BEQ &16af ; fire_not_pressed
&1664 d0 43    BNE &16a9 ; fire_pressed
; check_keys
&1666 b6 00    LDX &00,Y ; key_left
&1668 20 94 20 JSR &2094 ; check_for_keypress
&166b d0 06    BNE &1673 ; left_not_pressed
&166d a5 80    LDA &80 ; player_action
&166f 09 01    ORA #&01 ; PLAYER_LEFT
&1671 85 80    STA &80 ; player_action
; left_not_pressed
&1673 a4 0a    LDY &0a ; input_method
&1675 b6 01    LDX &01,Y ; key_right
&1677 20 94 20 JSR &2094 ; check_for_keypress
&167a d0 06    BNE &1682 ; right_not_pressed
&167c a5 80    LDA &80 ; player_action
&167e 09 02    ORA #&02 ; PLAYER_RIGHT
&1680 85 80    STA &80 ; player_action
; right_not_pressed
&1682 a4 0a    LDY &0a ; input_method
&1684 b6 02    LDX &02,Y ; key_up
&1686 20 94 20 JSR &2094 ; check_for_keypress
&1689 d0 06    BNE &1691 ; up_not_pressed
&168b a5 80    LDA &80 ; player_action
&168d 09 04    ORA #&04 ; PLAYER_UP
&168f 85 80    STA &80 ; player_action
 ; up_not_pressed
&1691 a4 0a    LDY &0a ; input_method
&1693 b6 03    LDX &03,Y ; key_down
&1695 20 94 20 JSR &2094 ; check_for_keypress
&1698 d0 06    BNE &16a0 ; down_not_pressed
&169a a5 80    LDA &80 ; player_action
&169c 09 08    ORA #&08 ; PLAYER_DOWN
&169e 85 80    STA &80 ; player_action
; down_not_pressed
&16a0 a4 0a    LDY &0a ; input_method
&16a2 b6 04    LDX &04,Y ; key_fire
&16a4 20 94 20 JSR &2094 ; check_for_keypress
&16a7 d0 06    BNE &16af ; fire_not_pressed
; fire_pressed
&16a9 a5 80    LDA &80 ; player_action
&16ab 09 10    ORA #&10 ; PLAYER_FIRE
&16ad 85 80    STA &80 ; player_action
; fire_not_pressed
&16af a9 00    LDA #&00
&16b1 85 f8    STA &f8 ; obstacles_found
&16b3 a6 70    LDX &70 ; player_screen_address_low
&16b5 a4 71    LDY &71 ; player_screen_address_high
&16b7 20 e0 65 JSR &65e0 ; calculate_subtile_address_from_screen_address
&16ba 86 8e    STX &8e ; player_subtile_right_address_low
&16bc 84 8f    STY &8f ; player_subtile_right_address_high
&16be 84 8d    STY &8d ; player_subtile_left_address_high
&16c0 ca       DEX
&16c1 86 8c    STX &8c ; player_subtile_left_address_low
&16c3 a2 02    LDX #&02                                             # Check two rows of subtiles
&16c5 a0 00    LDY #&00
&16c7 a5 70    LDA &70 ; player_screen_address_low
&16c9 29 07    AND #&07
&16cb f0 01    BEQ &16ce ; player_isn't_straddling_group_left
&16cd e8       INX                                                  # Add extra row if player sprite is straddling group
; player_isn't_straddling_group_left
&16ce a5 77    LDA &77 ; player_on_hopper_pad                       # Non-zero if player on hopper pad
&16d0 d0 05    BNE &16d7 ; player_isn't_on_platform_left
&16d2 a5 76    LDA &76 ; player_on_hopper                           # Non-zero if player not on hopper
&16d4 d0 01    BNE &16d7 ; player_isn't_on_platform_left
&16d6 e8       INX                                                  # Add extra row if player is on hopper
; player_isn't_on_platform_left
; check_for_obstacles_left
&16d7 b1 8c    LDA (&8c),Y ; player_subtile_left_address
&16d9 29 08    AND #&08 ; SUBTILE_NO_PLAYER
&16db d0 12    BNE &16ef ; left_subtile_has_obstacle
&16dd 18       CLC
&16de a5 8c    LDA &8c ; player_subtile_left_address_low
&16e0 69 20    ADC #&20                                             # Move down one subtile
&16e2 85 8c    STA &8c ; player_subtile_left_address_low
&16e4 a5 8d    LDA &8d ; player_subtile_left_address_high
&16e6 69 00    ADC #&00
&16e8 85 8d    STA &8d ; player_subtile_left_address_high
&16ea ca       DEX
&16eb d0 ea    BNE &16d7 ; check_for_obstacles_left
&16ed f0 0c    BEQ &16fb ; no_obstacle_to_left
; left_subtile_has_obstacle
&16ef a5 72    LDA &72 ; player_sprite                              # Is the player at the left of a subtile?
&16f1 29 03    AND #&03
&16f3 d0 06    BNE &16fb ; no_obstacle_to_left                      # Skip checking for left obstacle if not
&16f5 a5 f8    LDA &f8 ; obstacles_found
&16f7 09 01    ORA #&01 ; OBSTACLE_LEFT
&16f9 85 f8    STA &f8 ; obstacles_found
; no_obstacle_to_left
&16fb a2 02    LDX #&02                                             # Check two rows of subtiles
&16fd a0 02    LDY #&02
&16ff a5 70    LDA &70 ; player_screen_address_low
&1701 29 07    AND #&07
&1703 f0 01    BEQ &1706 ; player_isn't_straddling_group_right
&1705 e8       INX                                                  # Add extra row if player sprite is straddling group
; player_isn't_straddling_group_right
&1706 a5 77    LDA &77 ; player_on_hopper_pad                       # Non-zero if player on hopper pad
&1708 d0 05    BNE &170f ; player_isn't_on_platform_right
&170a a5 76    LDA &76 ; player_on_hopper                           # Non-zero if player not on hopper
&170c d0 01    BNE &170f ; player_isn't_on_platform_right
&170e e8       INX                                                  # Add extra row if player is on hopper
; player_isn't_on_platform_right
; check_for_obstacles_right
&170f b1 8e    LDA (&8e),Y ; player_subtile_right_address
&1711 29 08    AND #&08 ; SUBTILE_NO_PLAYER
&1713 d0 0b    BNE &1720 ; right_subtile_has_obstacle
&1715 18       CLC
&1716 98       TYA
&1717 69 20    ADC #&20                                             # Move down one subtile
&1719 a8       TAY
&171a ca       DEX
&171b d0 f2    BNE &170f ; check_for_obstacles_right
&171d 4c 26 17 JMP &1726 ; no_obstacle_to_right
; right_subtile_has_obstacle
&1720 a5 f8    LDA &f8 ; obstacles_found
&1722 09 02    ORA #&02 ; OBSTACLE_RIGHT
&1724 85 f8    STA &f8 ; obstacles_found
; no_obstacle_to_right
&1726 a5 2e    LDA &2e ; new_enemies_cooldown
&1728 f0 07    BEQ &1731 ; consider_adding_enemy
&172a 30 20    BMI &174c ; skip_adding_enemies
&172c c6 2e    DEC &2e ; new_enemies_cooldown
&172e 4c 4c 17 JMP &174c ; skip_adding_enemies
; consider_adding_enemy
&1731 a5 2f    LDA &2f ; new_enemies_needed
&1733 30 17    BMI &174c ; skip_adding_enemies
&1735 20 40 64 JSR &6440 ; rnd
&1738 29 03    AND #&03
&173a d0 10    BNE &174c ; skip_adding_enemies
&173c 20 bd 2d JSR &2dbd ; add_enemy
&173f a5 2f    LDA &2f ; new_enemies_needed
&1741 10 09    BPL &174c ; skip_adding_enemies
&1743 20 40 64 JSR &6440 ; rnd                                      # 1 in 8 chance
&1746 29 07    AND #&07
&1748 d0 02    BNE &174c ; skip_adding_enemies
&174a c6 2e    DEC &2e ; new_enemies_cooldown                       # of permanently killing an enemy
; skip_adding_enemies
&174c a5 76    LDA &76 ; player_on_hopper                           # Zero if player on hopper
&174e f0 1d    BEQ &176d ; skip_falling_and_walking_sound
&1750 a5 73    LDA &73 ; falling_time
&1752 f0 0e    BEQ &1762 ; consider_walking_sound
&1754 c9 01    CMP #&01
&1756 d0 15    BNE &176d ; skip_falling_and_walking_sound
&1758 a2 54    LDX #&54
&175a a0 60    LDY #&60 ; &6054 = player_falling_sound
&175c 20 3d 35 JSR &353d ; play_sound
&175f 4c 6d 17 JMP &176d ; skip_falling_and_walking_sound
; consider_walking_sound
&1762 a5 45    LDA &45 ; player_walking_direction
&1764 f0 07    BEQ &176d ; skip_falling_and_walking_sound
&1766 a2 d1    LDX #&d1
&1768 a0 20    LDY #&20 ; &20d1 = player_walking_sound
&176a 20 3d 35 JSR &353d ; play_sound
; skip_falling_and_walking_sound
; wait_for_vsync
&176d ad 40 02 LDA &0240 ; os_cfs_timeout_counter
&1770 c5 50    CMP &50 ; previous_cfs_timeout_counter
&1772 f0 f9    BEQ &176d ; wait_for_vsync
&1774 85 50    STA &50 ; previous_cfs_timeout_counter
&1776 20 d9 20 JSR &20d9 ; replot_player
&1779 20 71 25 JSR &2571 ; calculate_player_group_address_and_hopper_sprite
&177c a5 80    LDA &80 ; player_action
&177e 29 03    AND #&03 ; PLAYER_LEFT | PLAYER_RIGHT
&1780 c9 03    CMP #&03 ; PLAYER_LEFT | PLAYER_RIGHT
&1782 f0 66    BEQ &17ea ; player_not_moving_left_or_right
&1784 a5 f8    LDA &f8 ; obstacles_found
&1786 29 01    AND #&01 ; OBSTACLE_LEFT                             # Is there an obstacle to the left?
&1788 d0 2d    BNE &17b7 ; player_not_moving_left
&178a a5 80    LDA &80 ; player_action
&178c 29 01    AND #&01 ; PLAYER_LEFT                               # If not, does the player want to move left?
&178e f0 27    BEQ &17b7 ; player_not_moving_left
&1790 85 45    STA &45 ; player_walking_direction
&1792 a5 77    LDA &77 ; player_on_hopper_pad                       # Zero if player not on hopper pad
&1794 f0 04    BEQ &179a ; not_leaving_hopper_pad_to_left
&1796 a9 01    LDA #&01                                             # Non-zero to indicate player not on hopper
&1798 85 76    STA &76 ; player_on_hopper
; not_leaving_hopper_pad_to_left
&179a c6 72    DEC &72 ; player_sprite
&179c a5 72    LDA &72 ; player_sprite
&179e 29 07    AND #&07
&17a0 85 72    STA &72 ; player_sprite
&17a2 29 03    AND #&03
&17a4 c9 03    CMP #&03
&17a6 d0 09    BNE &17b1 ; not_new_subtile_to_left
&17a8 38       SEC
&17a9 a5 70    LDA &70 ; player_screen_address_low
&17ab e9 08    SBC #&08                                             # Move left four pixels
&17ad 85 70    STA &70 ; player_screen_address_low
&17af c6 74    DEC &74 ; below_player_subtile_address_low
; not_new_subtile_to_left
&17b1 a5 22    LDA &22 ; player_facing
&17b3 29 fe    AND #&fe                                             # Unset lowest bit to indicate facing left
&17b5 85 22    STA &22 ; player_facing
; player_not_moving_left
&17b7 a5 f8    LDA &f8 ; obstacles_found
&17b9 29 02    AND #&02 ; OBSTACLE_RIGHT                            # Is there an obstacle to the right?
&17bb d0 2d    BNE &17ea ; player_not_moving_left_or_right
&17bd a5 80    LDA &80 ; player_action
&17bf 29 02    AND #&02 : PLAYER_RIGHT                              # If not, does the player want to move right?
&17c1 f0 27    BEQ &17ea ; player_not_moving_left_or_right
&17c3 85 45    STA &45 ; player_walking_direction
&17c5 a5 77    LDA &77 ; player_on_hopper_pad
&17c7 f0 04    BEQ &17cd ; not_leaving_hopper_pad_to_right
&17c9 a9 01    LDA #&01
&17cb 85 76    STA &76 ; player_on_hopper
; not_leaving_hopper_pad_to_right
&17cd 18       CLC
&17ce a5 72    LDA &72 ; player_sprite
&17d0 29 07    AND #&07
&17d2 69 01    ADC #&01
&17d4 09 08    ORA #&08
&17d6 85 72    STA &72 ; player_sprite
&17d8 29 03    AND #&03
&17da d0 08    BNE &17e4 ; not_new_subtile_to_right
&17dc a5 70    LDA &70 ; player_screen_address_low
&17de 69 08    ADC #&08                                             # Move right four pixels
&17e0 85 70    STA &70 ; player_screen_address_low
&17e2 e6 74    INC &74 ; below_player_subtile_address_low
; not_new_subtile_to_right
&17e4 a5 22    LDA &22 ; player_facing
&17e6 09 01    ORA #&01                                             # Set lowest bit to indicate facing right
&17e8 85 22    STA &22 ; player_facing
; player_not_moving_left_or_right
&17ea a5 76    LDA &76 ; player_on_hopper                           # Zero if player on hopper
&17ec f0 03    BEQ &17f1 ; on_platform
; player_not_moving_up_or_down
&17ee 4c af 18 JMP &18af ; consider_bridging_platform
; on_platform
&17f1 a5 80    LDA &80 ; player_action
&17f3 29 0c    AND #&0c ; PLAYER_UP | PLAYER_DOWN
&17f5 c9 0c    CMP #&0c ; PLAYER_UP | PLAYER_DOWN
&17f7 f0 f5    BEQ &17ee ; player_not_moving_up_or_down
&17f9 a6 70    LDX &70 ; player_screen_address_low                  # Get the address of the subtile containing the platform
&17fb a4 71    LDY &71 ; player_screen_address_high
&17fd 20 2f 25 JSR &252f ; calculate_below_subtile_address_from_screen_address
&1800 38       SEC
&1801 8a       TXA
&1802 e9 60    SBC #&60                                             # Move up three subtiles
&1804 85 8c    STA &8c ; subtile_address_low
&1806 98       TYA
&1807 e9 00    SBC #&00
&1809 85 8d    STA &8d ; subtile_address_high
&180b a0 02    LDY #&02
&180d a5 72    LDA &72 ; player_sprite
&180f 29 03    AND #&03
&1811 d0 01    BNE &1814 ; check_for_obstacles_above
&1813 88       DEY                                                  # Player is three or two subtiles wide
; check_for_obstacles_above
&1814 b1 8c    LDA (&8c),Y ; subtile_address
&1816 29 08    AND #&08 ; SUBTILE_NO_PLAYER
&1818 d0 06    BNE &1820 ; top_subtile_has_obstacle
&181a 88       DEY
&181b 10 f7    BPL &1814 ; check_for_obstacles_above
&181d 4c 2c 18 JMP &182c ; no_obstacle_above
; top_subtile_has_obstacle
&1820 a5 70    LDA &70 ; player_screen_address_low
&1822 29 06    AND #&06
&1824 d0 06    BNE &182c ; no_obstacle_above                        # Player can move up if not aligned with group
&1826 a5 f8    LDA &f8 ; obstacles_found
&1828 09 04    ORA #&04 ; OBSTACLE_ABOVE
&182a 85 f8    STA &f8 ; obstacles_found
; no_obstacle_above
&182c a0 22    LDY #&22
&182e a5 72    LDA &72 ; player_sprite
&1830 29 03    AND #&03
&1832 d0 01    BNE &1835 ; check_for_obstacles_below
&1834 88       DEY                                                  # Player is three or two subtiles wide
; check_for_obstacles_below
&1835 b1 8e    LDA (&8e),Y ; player_subtile_right_address
&1837 29 08    AND #&08 ; SUBTILE_NO_PLAYER
&1839 d0 08    BNE &1843 ; bottom_subtile_has_obstacle
&183b 88       DEY
&183c c0 1f    CPY #&1f
&183e d0 f5    BNE &1835 ; check_for_obstacles_below
&1840 4c 49 18 JMP &1849 ; no_obstacle_below
; bottom_subtile_has_obstacle
&1843 a5 f8    LDA &f8 ; obstacles_found
&1845 09 08    ORA #&08 ; OBSTACLE_BELOW
&1847 85 f8    STA &f8 ; obstacles_found
; no_obstacle_below
&1849 a5 f8    LDA &f8 ; obstacles_found
&184b 29 04    AND #&04 ; OBSTACLE_ABOVE                            # Is there an obstacle above the player?
&184d d0 35    BNE &1884 ; align_player_with_group_up
&184f a5 80    LDA &80 ; player_action
&1851 29 04    AND #&04 ; PLAYER_UP                                 # If not, does the player want to move up?
&1853 f0 35    BEQ &188a ; player_not_moving_up
&1855 a5 f8    LDA &f8 ; obstacles_found
&1857 29 f7    AND #&f7
&1859 85 f8    STA &f8 ; obstacles_found
&185b 38       SEC
&185c a5 70    LDA &70 ; player_screen_address_low
&185e 29 07    AND #&07
&1860 e9 02    SBC #&02                                             # Move up two pixels
&1862 b0 19    BCS &187d ; move_up_within_group
&1864 38       SEC
&1865 a5 70    LDA &70 ; player_screen_address_low
&1867 e9 fa    SBC #&fa
&1869 85 70    STA &70 ; player_screen_address_low
&186b b0 02    BCS &186f ; skip_underflow
&186d c6 71    DEC &71 ; player_screen_address_high
; skip_underflow
&186f 38       SEC
&1870 a5 74    LDA &74 ; below_player_subtile_address_low
&1872 e9 20    SBC #&20                                             # Move up one subtile
&1874 85 74    STA &74 ; below_player_subtile_address_low
&1876 b0 02    BCS &187a ; skip_underflow
&1878 c6 75    DEC &75 ; below_player_subtile_address_high
; skip_underflow
&187a 4c 8a 18 JMP &188a ; player_not_moving_up
; move_up_within_group
&187d c6 70    DEC &70 ; player_screen_address_low
&187f c6 70    DEC &70 ; player_screen_address_low
&1881 4c 8a 18 JMP &188a ; player_not_moving_up
; align_player_with_group_up
&1884 a5 70    LDA &70 ; player_screen_address_low
&1886 29 f8    AND #&f8
&1888 85 70    STA &70 ; player_screen_address_low
; player_not_moving_up
&188a a5 f8    LDA &f8 ; obstacles_found
&188c 29 08    AND #&08 ; OBSTACLE_BELOW                            # Is there an obstacle below the player?
&188e d0 19    BNE &18a9 ; align_player_with_group_down
&1890 a5 80    LDA &80 ; player_action
&1892 29 08    AND #&08 ; PLAYER_DOWN                               # If not, does the player want to move down?
&1894 f0 19    BEQ &18af ; player_not_moving_down
&1896 a9 02    LDA #&02                                             # Move down two pixels
&1898 20 61 20 JSR &2061 ; move_player_down
&189b 18       CLC
&189c a5 74    LDA &74 ; below_player_subtile_address_low
&189e 69 20    ADC #&20                                             # Move down one subtile
&18a0 85 74    STA &74 ; below_player_subtile_address_low
&18a2 90 02    BCC &18a6 ; skip_overflow
&18a4 e6 75    INC &75 ; below_player_subtile_address_high
; skip_overflow
&18a6 4c af 18 JMP &18af ; player_not_moving_down
; align_player_with_group_down
&18a9 a5 70    LDA &70 ; player_screen_address_low
&18ab 29 f8    AND #&f8
&18ad 85 70    STA &70 ; player_screen_address_low
; player_not_moving_down
; consider_bridging_platform
&18af a5 76    LDA &76 ; player_on_hopper                           # Zero if player on hopper
&18b1 f0 16    BEQ &18c9 ; to_skip_bridging_platform
&18b3 a5 9e    LDA &9e ; player_in_pipe                             # Non-zero if player in pipe
&18b5 d0 12    BNE &18c9 ; to_skip_bridging_platform
&18b7 a5 81    LDA &81 ; previous_player_action
&18b9 29 08    AND #&08 ; PLAYER_DOWN
&18bb d0 0c    BNE &18c9 ; to_skip_bridging_platform                # Does the player want to create a bridging platform?
&18bd a5 80    LDA &80 ; player_action
&18bf 29 08    AND #&08 ; PLAYER_DOWN
&18c1 f0 06    BEQ &18c9 ; to_skip_bridging_platform                # No key repeat
&18c3 a5 71    LDA &71 ; player_screen_address_high
&18c5 c9 6d    CMP #&6d                                             # Is the player above the top of the screen?
&18c7 10 03    BPL &18cc ; consider_making_bridging_platform       
; to_skip_bridging_platform
&18c9 4c af 19 JMP &19af ; skip_bridging_platform
; consider_making_bridging_platform
&18cc a5 71    LDA &71 ; player_screen_address_high
&18ce c9 7d    CMP #&7d                                             # Is the player at or below the bottom of the screen?
&18d0 b0 f7    BCS &18c9 ; to_skip_bridging_platform
&18d2 a5 3d    LDA &3d ; player_fuel_high
&18d4 f0 f3    BEQ &18c9 ; to_skip_bridging_platform                # Does the player have fuel?
&18d6 a5 81    LDA &81 ; previous_player_action
&18d8 29 08    AND #&08 ; PLAYER_DOWN
&18da d0 ed    BNE &18c9 ; to_skip_bridging_platform
&18dc a5 80    LDA &80 ; player_action
&18de 29 08    AND #&08 ; PLAYER_DOWN
&18e0 f0 e7    BEQ &18c9 ; to_skip_bridging_platform
&18e2 a5 80    LDA &80 ; player_action
&18e4 29 03    AND #&03 ; PLAYER_LEFT | PLAYER_RIGHT
&18e6 d0 e1    BNE &18c9 ; to_skip_bridging_platform
&18e8 a6 70    LDX &70 ; player_screen_address_low
&18ea a4 71    LDY &71 ; player_screen_address_high
&18ec a5 73    LDA &73 ; falling_time
&18ee f0 04    BEQ &18f4 ; player_isn't_falling
&18f0 c8       INY                                                  # Calculate subtile address four tiles below player
&18f1 c8       INY
&18f2 c8       INY
&18f3 c8       INY
; player_isn't_falling
&18f4 88       DEY                                                  # (three if player isn't falling)
&18f5 20 e0 65 JSR &65e0 ; calculate_subtile_address_from_screen_address
&18f8 a0 02    LDY #&02
&18fa a5 72    LDA &72 ; player_sprite
&18fc 29 03    AND #&03
&18fe d0 01    BNE &1901 ; check_for_obstacles
&1900 88       DEY                                                  # Player is three or two subtiles wide
; check_for_obstacles
&1901 b1 6b    LDA (&6b),Y ; subtile_address
&1903 29 08    AND #&08 ; SUBTILE_NO_PLAYER
&1905 d0 0f    BNE &1916 ; obstacle_found
&1907 88       DEY
&1908 10 f7    BPL &1901 ; check_for_obstacles
&190a a5 73    LDA &73 ; falling_time
&190c f0 18    BEQ &1926 ; create_bridging_platform
&190e a5 71    LDA &71 ; player_screen_address_high
&1910 c9 7c    CMP #&7c
&1912 90 12    BCC &1926 ; create_bridging_platform
&1914 b0 04    BCS &191a ; align_player_with_group                  # Always branches
; obstacle_found
&1916 a5 73    LDA &73 ; falling_time
&1918 f0 af    BEQ &18c9 ; to_skip_bridging_platform
; align_player_with_group
&191a a5 70    LDA &70 ; player_screen_address_low
&191c 29 f8    AND #&f8                                             # Align player with group
&191e 85 70    STA &70 ; player_screen_address_low
&1920 a9 00    LDA #&00
&1922 85 73    STA &73 ; falling_time
&1924 e6 71    INC &71 ; player_screen_address_high
; create_bridging_platform
&1926 a0 00    LDY #&00
&1928 20 c2 20 JSR &20c2 ; find_bridging_platform_slot
&192b d0 52    BNE &197f ; to_skip_bridging_platform               # Non-zero if no slot available for new platform
&192d a5 70    LDA &70 ; player_screen_address_low
&192f 29 f8    AND #&f8                                             # Align platform with group
&1931 85 8e    STA &8e ; platform_screen_address_low
&1933 a5 73    LDA &73 ; falling_time
&1935 d0 0f    BNE &1946 ; skip_up_subtile
&1937 c6 71    DEC &71 ; player_screen_address_high
&1939 38       SEC
&193a a5 74    LDA &74 ; below_player_subtile_address_low
&193c e9 20    SBC #&20                                             # Move up a subtile if player isn't falling
&193e 85 74    STA &74 ; below_player_subtile_address_low
&1940 a5 75    LDA &75 ; below_player_subtile_address_high
&1942 e9 00    SBC #&00
&1944 85 75    STA &75 ; below_player_subtile_address_high
; skip_up_subtile
&1946 a6 8e    LDX &8e ; platform_screen_address_low
&1948 18       CLC
&1949 a5 72    LDA &72 ; player_sprite
&194b 29 02    AND #&02
&194d f0 05    BEQ &1954 ; skip_adjustment
&194f 8a       TXA
&1950 69 08    ADC #&08                                             # Move platform right four pixels
&1952 85 8e    STA &8e ; platform_screen_address_low
; skip_adjustment
&1954 a5 71    LDA &71 ; player_screen_address_high
&1956 69 02    ADC #&02                                             # Platform is two subtiles below player
&1958 84 6d    STY &6d ; platform_screen_address_high
&195a a8       TAY
&195b a5 73    LDA &73 ; falling_time
&195d f0 01    BEQ &1960 ; not_falling
&195f c8       INY                                                  # three if player is falling
; not_falling
&1960 a6 8e    LDX &8e ; player_group_address_low
&1962 20 e0 65 JSR &65e0 ; calculate_subtile_address_from_screen_address
&1965 86 8e    STX &8e ; platform_subtile_address_low
&1967 84 8f    STY &8f ; platform_subtile_address_high
&1969 a6 6d    LDX &6d ; platform_screen_address_high
&196b a0 00    LDY #&00
&196d b1 8e    LDA (&8e),Y ; platform_subtile_address
&196f 29 07    AND #&07 ; SUBTILE_GATE | SUBTILE_HIDE_PLAYER | SUBTILE_PIPE
&1971 c9 07    CMP #&07                                             # Never matches
&1973 d0 0d    BNE &1982 ; skip_unused_code                         # Always branches
&1975 ad fe 65 LDA &65fe ; unused_zero_one                          # Unused code
&1978 85 70    STA &70 ; player_screen_address_low
&197a ad ff 65 LDA &65ff ; unused_zero_two
&197d 85 71    STA &71 ; player_screen_address_high
; to_skip_bridging_platform
&197f 4c af 19 JMP &19af ; skip_bridging_platform
; skip_unused_code
&1982 b1 8e    LDA (&8e),Y ; platform_subtile_address
&1984 09 08    ORA #&08 ; SUBTILE_NO_PLAYER                         # Stop player falling through left half of platform
&1986 91 8e    STA (&8e),Y ; platform_subtile_address
&1988 c8       INY
&1989 b1 8e    LDA (&8e),Y ; platform_subtile_address
&198b 09 08    ORA #&08 ; SUBTILE_NO_PLAYER                         # Stop player falling through right half of platform
&198d 91 8e    STA (&8e),Y ; platform_subtile_address
&198f a5 8f    LDA &8f ; platform_subtile_address_high
&1991 29 03    AND #&03
&1993 09 e0    ORA #&e0                                             # Set time to live
&1995 9d 01 04 STA &0401,X ; bridging_platform_data + 1
&1998 a5 8e    LDA &8e ; platform_subtile_address_low
&199a 9d 00 04 STA &0400,X ; bridging_platform_data
&199d 38       SEC
&199e a5 3c    LDA &3c ; player_fuel_low
&19a0 e9 40    SBC #&40                                             # Temporary platform uses &0040 fuel
&19a2 85 3c    STA &3c ; player_fuel_low
&19a4 b0 02    BCS &19a8 ; skip_underflow
&19a6 c6 3d    DEC &3d ; player_fuel_high
; skip_underflow
&19a8 a2 5c    LDX #&5c
&19aa a0 60    LDY #&60 ; &605c = bridging_platform_sound
&19ac 20 3d 35 JSR &353d ; play_sound
; skip_bridging_platform
; consider_firing
&19af a5 80    LDA &80 ; player_action
&19b1 29 10    AND #&10 ; PLAYER_FIRE                               # Did the player press fire?
&19b3 f0 4f    BEQ &1a04 ; not_firing
&19b5 a5 7d    LDA &7d ; fire_screen_address_high
&19b7 d0 4b    BNE &1a04 ; not_firing
&19b9 a5 3f    LDA &3f ; player_ammunition_high                     # Does the player have ammunition?
&19bb f0 47    BEQ &1a04 ; not_firing
&19bd 38       SEC
&19be a5 3e    LDA &3e ; player_ammunition_low
&19c0 e9 20    SBC #&20                                             # Firing uses &0020 ammunition
&19c2 85 3e    STA &3e ; player_ammunition_low
&19c4 b0 02    BCS &19c8 ; skip_overflow
&19c6 c6 3f    DEC &3f ; player_ammunition_high
; skip_overflow
&19c8 a5 76    LDA &76 ; player_on_hopper                           # Zero if player on hopper
&19ca 49 01    EOR #&01
&19cc 85 78    STA &78 ; fire_type
&19ce a5 70    LDA &70 ; player_screen_address_low
&19d0 85 7c    STA &7c ; fire_screen_address_low
&19d2 85 8e    STA &8e ; screen_address_low                         # Unnecessary code
&19d4 a5 71    LDA &71 ; player_screen_address_high
&19d6 09 80    ORA #&80                                             # Top bit set to indicate fire doesn't need unplotting
&19d8 aa       TAX
&19d9 a5 70    LDA &70 ; player_screen_address_low
&19db 29 04    AND #&04
&19dd f0 01    BEQ &19e0 ; player_aligned_with_group
&19df e8       INX                                                  # Move down a group if player not aligned with group
; player_aligned_with_group
&19e0 a5 76    LDA &76 ; player_on_hopper                           # Zero if player on hopper
&19e2 f0 01    BEQ &19e5 ; player_is_on_platform
&19e4 e8       INX
; player_is_on_platform
&19e5 86 7d    STX &7d ; fire_screen_address_high
&19e7 86 8f    STX &8f ; screen_address_high                        # Unnecessary code
&19e9 a6 79    LDX &79 ; player_fire_direction
&19eb a5 76    LDA &76 ; player_on_hopper                           # Zero if player on hopper
&19ed f0 0a    BEQ &19f9 ; set_fire_direction
&19ef a2 81    LDX #&81 ; FIRE_LEFT | FIRE_NO_BOUNCE
&19f1 a5 72    LDA &72 ; player_sprite
&19f3 29 08    AND #&08                                             # Is the player facing right?
&19f5 f0 02    BEQ &19f9 ; set_fire_direction
&19f7 a2 82    LDX #&82 ; FIRE_RIGHT | FIRE_NO_BOUNCE
; set_fire_direction
&19f9 86 7a    STX &7a ; fire_direction
&19fb a2 44    LDX #&44
&19fd a0 60    LDY #&60 ; &6044 = player_firing_sound
&19ff a9 07    LDA #&07 ; Generate a sound (SOUND)
&1a01 20 f1 ff JSR &fff1 ; OSWORD
; not_firing
&1a04 a5 76    LDA &76 ; player_on_hopper                           # Zero if player on hopper
&1a06 d0 03    BNE &1a0b ; consider_falling
&1a08 4c b4 1a JMP &1ab4 ; skip_falling
; consider_falling
&1a0b 20 4e 20 JSR &204e ; check_if_player_can_fall                 # Returns negative set if no obstacle
&1a0e 30 09    BMI &1a19 ; make_player_fall
&1a10 b1 74    LDA (&74),Y ; below_subtile_address
&1a12 29 04    AND #&04 ; SUBTILE_PIPE                              # Is the player in a pipe?
&1a14 f0 03    BEQ &1a19 ; make_player_fall
&1a16 4c b0 1a JMP &1ab0 ; skip_falling_and_reset_falling_time      # If so, the player doesn't fall
; make_player_fall
&1a19 a4 73    LDY &73 ; falling_time
&1a1b b9 b1 20 LDA &20b1,Y ; falling_speeds
&1a1e 20 61 20 JSR &2061 ; move_player_down
&1a21 a5 73    LDA &73 ; falling_time
&1a23 c9 10    CMP #&10
&1a25 b0 02    BCS &1a29 ; skip_increase
&1a27 e6 73    INC &73 ; falling_time
; skip_increase
&1a29 20 4e 20 JSR &204e ; check_if_player_can_fall                 # Returns negative unset if obstacle 
&1a2c 10 03    BPL &1a31 ; player_falls_into_obstacle
; to_skip_falling
&1a2e 4c b4 1a JMP &1ab4 ; skip_falling
; player_falls_into_obstacle
&1a31 b1 74    LDA (&74),Y ; below_subtile_address
&1a33 29 04    AND #&04 ; SUBTILE_PIPE
&1a35 d0 f7    BNE &1a2e ; to_skip_falling
&1a37 b1 74    LDA (&74),Y ; below_subtile_address
&1a39 29 01    AND #&01 ; SUBTILE_GATE
&1a3b 49 01    EOR #&01
&1a3d d0 6b    BNE &1aaa ; align_player_with_group                  # Align player if obstacle isn't a horizontal gate
&1a3f a5 73    LDA &73 ; falling_time
&1a41 c9 10    CMP #&10
&1a43 30 65    BMI &1aaa ; align_player_with_group                  # Is the player falling into the gate at maximum speed?
&1a45 a5 74    LDA &74 ; below_player_subtile_address_low
&1a47 85 8e    STA &8e ; gate_subtile_address_low
&1a49 a5 75    LDA &75 ; below_player_subtile_address_high
&1a4b 85 8f    STA &8f ; gate_subtile_address_high
&1a4d 85 89    STA &89 ; bridging_platform_subtile_address_high
; find_start_of_gate_loop
&1a4f c6 8e    DEC &8e ; gate_subtile_address_low
&1a51 b1 8e    LDA (&8e),Y ; gate_subtile_address
&1a53 29 01    AND #&01 ; SUBTILE_GATE
&1a55 d0 f8    BNE &1a4f ; find_start_of_gate_loop
&1a57 88       DEY
&1a58 98       TYA
&1a59 18       CLC
&1a5a 65 8e    ADC &8e ; gate_subtile_low                           # Calculate screen address of gate
&1a5c 85 8e    STA &8e ; gate_subtile_low
&1a5e 85 88    STA &88 ; bridging_platform_subtile_address_low
&1a60 06 8e    ASL &8e ; gate_subtile_low
&1a62 26 8f    ROL &8f ; gate_subtile_high
&1a64 06 8e    ASL &8e ; gate_subtile_low
&1a66 26 8f    ROL &8f ; gate_subtile_high
&1a68 06 8e    ASL &8e ; gate_subtile_low / screen_address_low
&1a6a 26 8f    ROL &8f ; gate_subtile_high
&1a6c a5 8f    LDA &8f ; gate_subtile_high
&1a6e 09 60    ORA #&60
&1a70 85 8f    STA &8f ; screen_address_high
&1a72 a9 e0    LDA #&e0
&1a74 85 8c    STA &8c ; sprite_address_low
&1a76 a9 40    LDA #&40 ; &40e0 = bridging_platform_frame_7
&1a78 85 8d    STA &8d ; sprite_address_high
&1a7a a2 04    LDX #&04
&1a7c a0 01    LDY #&01
&1a7e 20 00 65 JSR &6500 ; plot_aligned_sprite_using_write          # Plot bridging platform over gate
&1a81 a0 00    LDY #&00
&1a83 20 c2 20 JSR &20c2 ; find_bridging_platform_slot
&1a86 a5 89    LDA &89 ; bridging_platform_subtile_address_high     # Add two bridging platforms in place of gate
&1a88 29 03    AND #&03
&1a8a 09 80    ORA #&80                                             # Set time to live
&1a8c 99 01 04 STA &0401,Y ; bridging_platform_data + 1
&1a8f a5 88    LDA &88 ; bridging_platform_subtile_address_low
&1a91 99 00 04 STA &0400,Y ; bridging_platform_data + 1
&1a94 a0 00    LDY #&00
&1a96 20 c2 20 JSR &20c2 ; find_bridging_platform_slot
&1a99 a5 89    LDA &89 ; bridging_platform_subtile_address_high
&1a9b 29 03    AND #&03
&1a9d 09 80    ORA #&80                                             # Set time to live
&1a9f 99 01 04 STA &0401,Y ; bridging_platform_data + 1
&1aa2 a5 88    LDA &88 ; bridging_platform_subtile_address_low
&1aa4 18       CLC
&1aa5 69 02    ADC #&02
&1aa7 99 00 04 STA &0400,Y ; bridging_platform_data
; align_player_with_group
&1aaa a5 70    LDA &70 ; player_screen_address_low
&1aac 29 f8    AND #&f8
&1aae 85 70    STA &70 ; player_screen_address_low
; skip_falling_and_reset_falling_time
&1ab0 a9 00    LDA #&00
&1ab2 85 73    STA &73 ; falling_time
; skip_falling 
&1ab4 a9 00    LDA #&00
&1ab6 85 77    STA &77 ; player_on_hopper_pad
&1ab8 a5 72    LDA &72 ; player_sprite
&1aba 29 03    AND #&03
&1abc d0 1f    BNE &1add ; not_hopper_pad
&1abe a5 70    LDA &70 ; player_screen_address_low
&1ac0 29 f8    AND #&f8
&1ac2 c5 64    CMP &64 ; hopper_pad_screen_address_low
&1ac4 d0 17    BNE &1add ; not_hopper_pad
&1ac6 a5 71    LDA &71 ; player_screen_address_high
&1ac8 c5 65    CMP &65 ; hopper_pad_screen_address_high
&1aca d0 11    BNE &1add ; not_hopper_pad
&1acc a9 01    LDA #&01
&1ace 85 77    STA &77 ; player_on_hopper_pad
&1ad0 a5 70    LDA &70 ; player_screen_address_low
&1ad2 29 f8    AND #&f8
&1ad4 85 70    STA &70 ; player_screen_address_low
&1ad6 a9 00    LDA #&00                                             # Zero to indicate player on hopper
&1ad8 85 76    STA &76 ; player_on_hopper
&1ada 20 71 25 JSR &2571 ; calculate_player_group_address_and_hopper_sprite
; not_hopper_pad
&1add a5 76    LDA &76 ; player_on_hopper
&1adf c5 21    CMP &21 ; previous_player_on_hopper
&1ae1 f0 1a    BEQ &1afd ; no_change_of_platform
&1ae3 a5 64    LDA &64 ; hopper_pad_screen_address_low
&1ae5 85 8e    STA &8e ; screen_address_low
&1ae7 a5 65    LDA &65 ; hopper_pad_screen_address_high
&1ae9 18       CLC
&1aea 69 02    ADC #&02
&1aec 85 8f    STA &8f ; screen_address_high
&1aee a9 20    LDA #&20
&1af0 85 8c    STA &8c ; sprite_address_low
&1af2 a9 41    LDA #&41 ; &4120 = hopper_frame_1
&1af4 85 8d    STA &8d ; sprite_address_high
&1af6 a2 02    LDX #&02                                             # 8 pixels wide
&1af8 a0 01    LDY #&01                                             # 8 pixels high
&1afa 20 ad 65 JSR &65ad ; plot_aligned_sprite_using_eor
; no_change_of_platform
&1afd a5 72    LDA &72 ; player_sprite
&1aff 29 03    AND #&03
&1b01 d0 60    BNE &1b63 ; set_player_not_in_pipe
&1b03 38       SEC
&1b04 a5 74    LDA &74 ; below_player_subtile_address_low
&1b06 e9 61    SBC #&61                                             # Move up three subtiles, left one subtile
&1b08 85 8c    STA &8c ; subtile_address_low
&1b0a a5 75    LDA &75 ; below_player_subtile_address_high
&1b0c e9 00    SBC #&00
&1b0e 85 8d    STA &8d ; subtile_address_high
&1b10 a0 21    LDY #&21                                             # Consider subtile (+1, +1), i.e. (0, -2)
&1b12 b1 8c    LDA (&8c),Y ; subtile_address
&1b14 29 0c    AND #&0c ; SUBTILE_NO_PLAYER | SUBTILE_PIPE
&1b16 c9 04    CMP #&04 ; SUBTILE_PIPE
&1b18 d0 49    BNE &1b63 ; set_player_not_in_pipe
&1b1a a0 22    LDY #&22                                             # Consider subtile (+2, +1), i.e. (1, -2)
&1b1c b1 8c    LDA (&8c),Y ; subtile_address
&1b1e 29 0c    AND #&0c ; SUBTILE_NO_PLAYER | SUBTILE_PIPE
&1b20 c9 04    CMP #&04 ; SUBTILE_PIPE
&1b22 d0 3f    BNE &1b63 ; set_player_not_in_pipe                   # If both are pipes,
&1b24 a5 75    LDA &75 ; below_player_subtile_address_high
&1b26 c9 05    CMP #&05
&1b28 f0 19    BEQ &1b43 ; skip_second_check                        # and the player is not at the top of the screen,
&1b2a a5 70    LDA &70 ; player_screen_address_low
&1b2c 29 06    AND #&06
&1b2e d0 13    BNE &1b43 ; skip_second_check
&1b30 a0 01    LDY #&01                                             # Consider subtile (+1, 0), i.e. (0, -3)
&1b32 b1 8c    LDA (&8c),Y ; subtile_address
&1b34 29 0c    AND #&0c ; SUBTILE_NO_PLAYER | SUBTILE_PIPE
&1b36 c9 04    CMP #&04 ; SUBTILE_PIPE
&1b38 d0 29    BNE &1b63 ; set_player_not_in_pipe
&1b3a c8       INY                                                  # Consider subtile (+2, 0), i.e. (1, -3)
&1b3b b1 8c    LDA (&8c),Y ; subtile_address
&1b3d 29 0c    AND #&0c ; SUBTILE_NO_PLAYER | SUBTILE_PIPE
&1b3f c9 04    CMP #&04 ; SUBTILE_PIPE
&1b41 d0 20    BNE &1b63 ; set_player_not_in_pipe                   # If both are pipes,
; skip_second_check
&1b43 a5 70    LDA &70 ; player_screen_address_low
&1b45 29 06    AND #&06
&1b47 e9 02    SBC #&02
&1b49 90 0a    BCC &1b55 ; align_player
&1b4b a5 70    LDA &70 ; player_screen_address_low
&1b4d 29 fe    AND #&fe
&1b4f e9 02    SBC #&02
&1b51 85 70    STA &70 ; player_screen_address_low
&1b53 b0 0a    BCS &1b5f ; set_player_in_pipe
; align_player
&1b55 a5 70    LDA &70 ; player_screen_address_low
&1b57 29 f8    AND #&f8
&1b59 09 06    ORA #&06
&1b5b 85 70    STA &70 ; player_screen_address_low
&1b5d c6 71    DEC &71 ; player_screen_address_high
; set_player_in_pipe
&1b5f a9 01    LDA #&01                                             # Non-zero to indicate player in pipe
&1b61 d0 02    BNE &1b65 ; update_player_in_pipe                    # Always branches
; set_player_not_in_pipe
&1b63 a9 00    LDA #&00
; update_player_in_pipe
&1b65 85 9e    STA &9e ; player_in_pipe
&1b67 a5 76    LDA &76 ; player_on_hopper                           # Zero if player on hopper
&1b69 f0 06    BEQ &1b71 ; skip_lower_check
&1b6b a5 71    LDA &71 ; player_screen_address_high
&1b6d c9 7d    CMP #&7d                                             # If not, is the player at the bottom of the screen?
&1b6f d0 24    BNE &1b95 ; not_falling_into_new_room
; skip_check_check
&1b71 a5 71    LDA &71 ; player_screen_address_high
&1b73 c9 7c    CMP #&7c                                             # If so, is the platform at the bottom of the screen?
&1b75 30 1e    BMI &1b95 ; not_falling_into_new_room
&1b77 a5 70    LDA &70 ; player_screen_address_low
&1b79 29 07    AND #&07
&1b7b f0 18    BEQ &1b95 ; not_falling_into_new_room
&1b7d a9 6d    LDA #&6d                                             # Put player at top of screen
&1b7f 85 71    STA &71 ; player_screen_address_high
&1b81 a5 70    LDA &70 ; player_screen_address_low
&1b83 29 f8    AND #&f8
&1b85 85 70    STA &70 ; player_screen_address_low
&1b87 18       CLC
&1b88 a5 7e    LDA &7e ; player_room_low
&1b8a 69 10    ADC #&10                                             # Move player down a room
&1b8c 85 7e    STA &7e ; player_room_low
&1b8e 90 02    BCC &1b92 ; skip_overflow
&1b90 e6 7f    INC &7f ; player_room_high
; skip_overflow
&1b92 4c 21 13 JMP &1321 ; enter_room
; not_falling_into_new_room
&1b95 a5 71    LDA &71 ; player_screen_address_high
&1b97 c9 6c    CMP #&6c                                             # Is the player at the top of the screen?
&1b99 d0 1e    BNE &1bb9 ; not_ascending_into_new_room
&1b9b a9 7c    LDA #&7c                                             # Put player at bottom of screen
&1b9d 85 71    STA &71 ; player_screen_address_high
&1b9f a5 70    LDA &70 ; player_screen_address_low
&1ba1 29 f8    AND #&f8
&1ba3 05 76    ORA &76 ; player_on_hopper                           # Zero if player on hopper
&1ba5 85 70    STA &70 ; player_screen_address_low
&1ba7 a9 07    LDA #&07
&1ba9 85 75    STA &75 ; below_player_subtile_address_high          # Unnecessary code
&1bab 38       SEC
&1bac a5 7e    LDA &7e ; player_room_low
&1bae e9 10    SBC #&10                                             # Move player up a room
&1bb0 85 7e    STA &7e ; player_room_low
&1bb2 b0 02    BCS &1bb6 ; skip_underflow
&1bb4 c6 7f    DEC &7f ; player_room_high
; skip_underflow
&1bb6 4c 21 13 JMP &1321 ; enter_room
; not_ascending_into_new_room
&1bb9 a5 72    LDA &72 ; player_sprite
&1bbb 29 03    AND #&03
&1bbd c9 03    CMP #&03
&1bbf d0 1f    BNE &1be0 ; not_moving_right_into_new_room           # Is the player about to move right into a new subtile?
&1bc1 a5 74    LDA &74 ; below_player_subtile_address_low
&1bc3 29 1f    AND #&1f
&1bc5 c9 1d    CMP #&1d                                             # Is the player at the right of the screen?
&1bc7 d0 17    BNE &1be0 ; not_moving_right_into_new_room
&1bc9 a5 70    LDA &70 ; player_screen_address_low
&1bcb 29 07    AND #&07                                             # Put player at left of screen
&1bcd 85 70    STA &70 ; player_screen_address_low
&1bcf a5 72    LDA &72 ; player_sprite
&1bd1 29 f8    AND #&f8
&1bd3 09 01    ORA #&01                                             # Put player at left of subtile
&1bd5 85 72    STA &72 ; player_sprite
&1bd7 e6 7e    INC &7e ; player_room_low                            # Move player right a room
&1bd9 d0 02    BNE &1bdd ; skip_overflow
&1bdb e6 7f    INC &7f ; player_room_high
; skip_overflow
&1bdd 4c 21 13 JMP &1321 ; enter_room
; not_moving_right_into_new_room
&1be0 a5 72    LDA &72 ; player_sprite
&1be2 29 03    AND #&03
&1be4 d0 24    BNE &1c0a ; not_moving_left_into_new_room            # Is the player about to move left into a new subtile?
&1be6 a5 74    LDA &74 ; below_player_subtile_address_low
&1be8 29 1f    AND #&1f
&1bea d0 1e    BNE &1c0a ; not_moving_left_into_new_room            # Is the player at the left of the screen?
&1bec a5 70    LDA &70 ; player_screen_address_low
&1bee 29 07    AND #&07
&1bf0 09 e8    ORA #&e8                                             # Put player at right of screen
&1bf2 85 70    STA &70 ; player_screen_address_low
&1bf4 a5 72    LDA &72 ; player_sprite
&1bf6 29 f8    AND #&f8
&1bf8 09 02    ORA #&02                                             # Put player at right of subtile
&1bfa 85 72    STA &72 ; player_sprite
&1bfc 38       SEC
&1bfd a5 7e    LDA &7e ; player_room_low
&1bff e9 01    SBC #&01                                             # Move player left a room
&1c01 85 7e    STA &7e ; player_room_low
&1c03 b0 02    BCS &1c07 ; skip_underflow
&1c05 c6 7f    DEC &7f ; player_room_high
; skip_underflow
&1c07 4c 21 13 JMP &1321 ; enter_room
; not_moving_left_into_new_room
&1c0a 20 d9 20 JSR &20d9 ; replot_player
&1c0d 20 0f 22 JSR &220f ; update_fire
&1c10 a9 00    LDA #&00                                             # Update and replot enemies
&1c12 20 b6 2e JSR &2eb6 ; update_enemies
&1c15 20 45 20 JSR &2045 ; update_scenery
&1c18 a5 71    LDA &71 ; player_screen_address_high
&1c1a c5 59    CMP &59 ; room_item_screen_address_high              # Does the player overlap the room item vertically?
&1c1c f0 02    BEQ &1c20 ; player_is_vertically_aligned_with_item
&1c1e b0 3c    BCS &1c5c ; to_done_collecting
; player_is_vertically_aligned_with_item
&1c20 a2 02    LDX #&02
&1c22 a5 70    LDA &70 ; player_screen_address_low
&1c24 29 07    AND #&07
&1c26 d0 01    BNE &1c29 ; player_is_aligned_with_group
&1c28 ca       DEX
; player_is_aligned_with_group
&1c29 8a       TXA
&1c2a 18       CLC
&1c2b 65 71    ADC &71 ; player_screen_address_high
&1c2d c5 59    CMP &59 ; room_item_screen_address_high
&1c2f 90 2b    BCC &1c5c ; to_done_collecting
&1c31 a5 70    LDA &70 ; player_screen_address_low                  # If so, does the player overlap it horizontally?
&1c33 29 f8    AND #&f8
&1c35 c5 58    CMP &58 ; room_item_screen_address_low
&1c37 f0 02    BEQ &1c3b ; player_is_horizontally_aligned_with_item
&1c39 b0 21    BCS &1c5c ; to_done_collecting
; player_is_horizontally_aligned_with_item
&1c3b 18       CLC
&1c3c 69 08    ADC #&08
&1c3e c5 58    CMP &58 ; room_item_screen_address_low
&1c40 90 1a    BCC &1c5c ; to_done_collecting
&1c42 a5 56    LDA &56 ; room_item_sprite                           # Is the item a boost?
&1c44 c9 05    CMP #&05 ; ITEM_LIVES
&1c46 f0 2d    BEQ &1c75 ; boost_lives
&1c48 c9 03    CMP #&03 ; ITEM_AMMO
&1c4a 90 34    BCC &1c80 ; boost_energy
&1c4c f0 7a    BEQ &1cc8 ; boost_ammunition
&1c4e c9 04    CMP #&04 ; ITEM_FUEL
&1c50 f0 3c    BEQ &1c8e ; boost_fuel
&1c52 c9 06    CMP #&06 ; ITEM_RANDOM
&1c54 f0 40    BEQ &1c96 ; random_boost
&1c56 a5 80    LDA &80 ; player_action                              # If not, the item is a pyramid
&1c58 29 04    AND #&04 ; PLAYER_UP
&1c5a d0 03    BNE &1c5f ; player_pressing_up_on_item
; to_done_collecting
&1c5c 4c ec 1c JMP &1cec ; done_collecting
; player_pressing_up_on_item
&1c5f a5 76    LDA &76 ; player_on_hopper                           # Zero if player on hopper
&1c61 f0 f9    BEQ &1c5c ; to_done_collecting                       # Can't enter pyramid while on hopper
&1c63 a0 04    LDY #&04
; check_for_pass_loop
&1c65 88       DEY
&1c66 30 f4    BMI &1c5c ; to_done_collecting                       # Can't enter pyramid without pass
&1c68 b9 0f 00 LDA &000f,Y ; pockets
&1c6b c9 09    CMP #&09 ; ITEM_PASS
&1c6d d0 f6    BNE &1c65 ; check_for_pass_loop
&1c6f 20 2a 10 JSR &102a ; enter_pyramid
&1c72 4c 1b 13 JMP &131b ; enter_room_after_pyramid

; boost_lives
&1c75 18       CLC
&1c76 f8       SED
&1c77 a5 49    LDA &49 ; player_lives
&1c79 69 01    ADC #&01                                             # Gain one life
&1c7b 85 49    STA &49 ; player_lives
&1c7d d8       CLD
&1c7e d0 4e    BNE &1cce ; done_boosting                            # Always branches

; boost_energy
&1c80 aa       TAX                                                  # Amount of energy depends on item collected
; boost_energy_with_X
&1c81 bd 8b 1c LDA &1c8b,X ; energy_boost_table
&1c84 18       CLC
&1c85 65 3b    ADC &3b ; player_energy_high
&1c87 85 3b    STA &3b ; player_energy_high
&1c89 d0 43    BNE &1cce ; done_boosting                            # Always branches

; energy_boost_table
&1c8b 10 0b 06

; boost_fuel
&1c8e a5 3d    STA &3d ; player_fuel_high
&1c90 69 08    ADC #&08                                             # Gain &0800 fuel
&1c92 85 3d    STA &3d ; player_fuel_high
&1c94 d0 38    BNE &1cce ; done_boosting                            # Always branches

; random_boost
&1c96 a2 00    LDX #&00                                             # Score 100 for collecting a random boost
&1c98 a0 01    LDY #&01
&1c9a 20 4f 35 JSR &354f ; increase_score
&1c9d 20 40 64 JSR &6440 ; rnd                                      # Choose a random number between 6 and 9
&1ca0 29 03    AND #&03
&1ca2 18       CLC
&1ca3 69 06    ADC #&06
&1ca5 85 8e    STA &8e ; unused                                     # Unnecessary code
&1ca7 a0 00    LDY #&00
&1ca9 a2 00    LDX #&00
&1cab a5 49    LDA &49 ; player_lives
&1cad f0 c6    BEQ &1c75 ; boost_lives
; find_lowest_bar_loop                                              # Find lowest of energy, fuel and ammunition
&1caf b5 3b    LDA &3b,X ; player_energy_high
&1cb1 d9 3b 00 CMP &003b,Y ; player_energy_high
&1cb4 b0 02    BCS &1cb8 ; skip_swap
&1cb6 8a       TXA
&1cb7 a8       TAY
; skip_swap
&1cb8 e8       INX
&1cb9 e8       INX
&1cba e0 06    CPX #&06
&1cbc d0 f1    BNE &1caf ; find_lowest_bar_loop
&1cbe a2 00    LDX #&00                                             # Gain &1000 energy
&1cc0 c0 00    CPY #&00
&1cc2 f0 bd    BEQ &1c81 ; boost_energy_with_X
&1cc4 c0 02    CPY #&02
&1cc6 f0 c6    BEQ &1c8e ; boost_fuel
; boost_ammunition
&1cc8 a5 3f    LDA &3f ; player_ammunition_high
&1cca 69 0b    ADC #&0b                                             # Gain &0b00 ammunition
&1ccc 85 3f    STA &3f ; player_ammunition_high
; done_boosting
&1cce a5 58    LDA &58 ; room_item_screen_address_low
&1cd0 85 8e    STA &8e ; screen_address_low
&1cd2 a5 59    LDA &59 ; room_item_screen_address_high
&1cd4 85 8f    STA &8f ; screen_address_high
&1cd6 a5 56    LDA &56 ; room_item_sprite
&1cd8 a6 55    LDX &55 ; room_item_colour_mask
&1cda a0 ff    LDY #&ff                                             # EOR 
&1cdc 20 b3 0b JSR &0bb3 ; plot_packed_two_colour_sprite            # Unplot item from room
&1cdf a0 00    LDY #&00
&1ce1 98       TYA
&1ce2 91 53    STA (&53),Y ; room_item_data_address                 # Remove item from room_item_data
&1ce4 c8       INY
&1ce5 91 53    STA (&53),Y; room_item_data_address
&1ce7 85 59    STA &59 ; room_item_screen_address_high              # Zero to indicate item is no longer in room
&1ce9 20 24 0e JSR &0e24 ; play_enter_teleport_sound
; done_collecting
&1cec 38       SEC
&1ced a5 3a    LDA &3a ; player_energy_low
&1cef e9 01    SBC #&01                                             # Lose &0001 energy per frame
&1cf1 85 3a    STA &3a ; player_energy_low
&1cf3 b0 02    BCS &1cf7 ; skip_underflow
&1cf5 c6 3b    DEC &3b ; player_energy_high
; skip_underflow
&1cf7 a5 3b    LDA &3b ; player_energy_high
&1cf9 10 04    BPL &1cff ; skip_floor
&1cfb a9 00    LDA #&00
; skip_floor
&1cfd 85 3b    STA &3b ; player_energy_high
&1cff 20 d4 23 JSR &23d4 ; plot_status
; check_for_player_entering_teleport
&1d02 a5 f6    LDA &f6 ; teleport_screen_address_low
&1d04 c5 70    CMP &70 ; player_screen_address_low
&1d06 d0 11    BNE &1d19 ; not_teleport
&1d08 a5 f7    LDA &f7 ; teleport_screen_address_high
&1d0a c5 71    CMP &71 ; player_screen_address_high
&1d0c d0 0b    BNE &1d19 ; not_teleport
&1d0e a9 13    LDA #&13 ; Wait for v-sync
&1d10 20 f4 ff JSR &fff4 ; OSBYTE
&1d13 20 2b 0e JSR &0e2b ; enter_teleport
&1d16 4c 21 13 JMP &1321 ; enter_room
; not_teleport
&1d19 a5 72    LDA &72 ; player_sprite
&1d1b 29 03    AND #&03
&1d1d d0 2f    BNE &1d4e ; not_passage                              # Is the player horizontally aligned with a subtile?
&1d1f a5 70    LDA &70 ; player_screen_address_low
&1d21 c5 4c    CMP &4c ; passage_screen_address_low
&1d23 d0 29    BNE &1d4e ; not_passage
&1d25 a5 71    LDA &71 ; player_screen_address_high
&1d27 c5 4d    CMP &4d ; passage_screen_address_high
&1d29 d0 23    BNE &1d4e ; not_passage
&1d2b a5 4e    LDA &4e ; passage_destination_screen_address_low
&1d2d 85 70    STA &70 ; player_screen_address_low
&1d2f a5 4f    LDA &4f ; passage_destination_screen_address_high
&1d31 85 71    STA &71 ; player_screen_address_high
&1d33 a5 4b    LDA &4b ; passage_destination_room_low
&1d35 85 7e    STA &7e ; player_room_low
&1d37 a5 72    LDA &72 ; player_sprite
&1d39 29 fc    AND #&fc                                             # Align player horizontally with subtile
&1d3b 05 4a    ORA &4a ; passage_direction
&1d3d 85 72    STA &72 ; player_sprite
&1d3f a2 19    LDX #&19
&1d41 a0 25    LDY #&25; &2519 = entering_passage_sound
&1d43 20 2b 35 JSR &352b ; play_sound_using_envelope
&1d46 a9 0a    LDA #&0a
&1d48 20 42 35 JSR &3542 ; wait_for_a_frames
&1d4b 4c 21 13 JMP &1321 ; enter_room
; not_passage
&1d4e 38       SEC
&1d4f a5 70    LDA &70 ; player_screen_address_low
&1d51 29 f8    AND #&f8
&1d53 e9 10    SBC #&10
&1d55 c5 0d    CMP &0d ; gate_screen_address_low
&1d57 f0 07    BEQ &1d60 ; consider_gate
&1d59 18       CLC
&1d5a 69 20    ADC #&20
&1d5c c5 0d    CMP &0d ; gate_screen_address_low
&1d5e d0 30    BNE &1d90 ; not_opening_gate
; consider_gate
&1d60 a5 72    LDA &72 ; player_sprite
&1d62 29 03    AND #&03
&1d64 d0 2a    BNE &1d90 ; not_opening_gate                         # Is the player horizontally aligned with a subtile?
&1d66 a0 04    LDY #&04
; check_for_key_loop
&1d68 88       DEY
&1d69 30 25    BMI &1d90 ; not_opening_gate                         # Can't open gate without key
&1d6b b9 0f 00 LDA &000f,Y ; pockets
&1d6e c9 0a    CMP #&0a ; ITEM_KEY
&1d70 d0 f6    BNE &1d68 ; check_for_key_loop
; player_has_key
&1d72 20 24 35 JSR &3524 ; flush_buffers
&1d75 a2 fb    LDX #&fb
&1d77 a0 24    LDY #&24 ; &24fb = opening_gate_sound
&1d79 20 2b 35 JSR &352b ; play_sound_using_envelope
&1d7c a9 11    LDA #&11
&1d7e 20 42 35 JSR &3542 ; wait_for_a_frames
&1d81 20 66 23 JSR &2366 ; plot_gates                               # Unplot gate
&1d84 b9 c4 61 LDA &61c4,Y ; gate_table + 1
&1d87 09 02    ORA #&02                                             # Set &02 to indicate gate isn't present
&1d89 99 c4 61 STA &61c4,Y ; gate_table + 1
&1d8c a9 01    LDA #&01                                             # Prevent player touching gate again
&1d8e 85 0d    STA &0d ; gate_screen_address_low
; not_opening_gate
; check_for_player_collecting_core_element
&1d90 a5 76    LDA &76 ; player_on_hopper
&1d92 f0 12    BEQ &1da6 ; not_collecting_core_element
&1d94 a5 80    LDA &80 ; player_action
&1d96 29 04    AND #&04 ; PLAYER_UP                                 # Player must press up
&1d98 f0 0c    BEQ &1da6 ; not_collecting_core_element
&1d9a a5 81    LDA &81 ; previous_player_action
&1d9c 29 04    AND #&04 ; PLAYER_UP
&1d9e d0 06    BNE &1da6 ; not_collecting_core_element
&1da0 a5 80    LDA &80 ; player_action
&1da2 29 03    AND #&03 ; PLAYER_LEFT | PLAYER_RIGHT                # without left or right to collect core element
&1da4 f0 03    BEQ &1da9 ; player_is_trying_to_collect_core_element
; not_collecting_core_element
&1da6 4c 5d 1e JMP &1e5d ; skip_collecting_core_element
; player_is_trying_to_collect_core_element
&1da9 a2 11    LDX #&11
&1dab a0 25    LDY #&25 ; &2511 = collecting_sound
&1dad 20 3d 35 JSR &353d ; play_sound
&1db0 a9 00    LDA #&00                                             # For each core element,
&1db2 85 8d    STA &8d ; core_element_to_consider
; consider_core_elements_loop
&1db4 a6 8d    LDX &8d ; core_element_to_consider
&1db6 bd 28 05 LDA &0528,X ; core_elements_data + 0                 # room_low of core element
&1db9 c5 7e    CMP &7e ; player_room_low
&1dbb d0 4e    BNE &1e0b ; consider_next_core_element               # is it in the same room as the player?
&1dbd bd 29 05 LDA &0529,X ; core_elements_data + 1
&1dc0 29 03    AND #&03                                             # room_high of core element
&1dc2 c5 7f    CMP &7f ; player_room_high
&1dc4 d0 45    BNE &1e0b ; consider_next_core_element
&1dc6 bd 29 05 LDA &0529,X ; core_elements_data + 1
&1dc9 29 f8    AND #&f8                                             # screen_address_low of core element
&1dcb 38       SEC
&1dcc e9 18    SBC #&18
&1dce 90 04    BCC &1dd4 ; skip_checking_left_edge
&1dd0 c5 70    CMP &70 ; player_screen_address_low
&1dd2 b0 37    BCS &1e0b ; consider_next_core_element               # Is the player overlapping it horizontally?
; skip_checking_left_edge
&1dd4 69 20    ADC #&20
&1dd6 b0 04    BCS &1ddc ; skip_checking_right_edge
&1dd8 c5 70    CMP &70 ; player_screen_address_low
&1dda 90 2f    BCC &1e0b ; consider_next_core_element
; skip_checking_right_edge
&1ddc bd 2a 05 LDA &052a,X ; core_elements_data + 2                 # screen_address_high of core element
&1ddf e9 02    SBC #&02
&1de1 c5 71    CMP &71 ; player_screen_address_high
&1de3 b0 26    BCS &1e0b ; consider_next_core_element               # Is the player overlapping it vertically?
&1de5 69 03    ADC #&03
&1de7 c5 71    CMP &71 ; player_screen_address_high
&1de9 90 20    BCC &1e0b ; consider_next_core_element
; player_is_collecting_core_element
&1deb bd 29 05 LDA &0529,X ; core_elements_data + 1
&1dee 29 f8    AND #&f8
&1df0 85 8e    STA &8e ; screen_address_low
&1df2 a9 03    LDA #&03                                             # Set room_high to &3
&1df4 9d 29 05 STA &0529,X ; core_elements_data + 1                 # to indicate core element is no longer in room 
&1df7 bd 2a 05 LDA &052a,X ; core_elements_data + 2
&1dfa 85 8f    STA &8f ; screen_address_high
&1dfc bd 2b 05 LDA &052b,X ; core_elements_data + 3
&1dff 85 86    STA &86 ; core_element_collected
&1e01 a2 ff    LDX #&ff                                             # White
&1e03 a0 ff    LDY #&ff                                             # EOR
&1e05 20 b3 0b JSR &0bb3 ; plot_packed_two_colour_sprite            # Unplot core element
&1e08 4c 1a 1e JMP &1e1a ; consider_dropping_core_element
; consider_next_core_element
&1e0b 18       CLC
&1e0c a5 8d    LDA &8d ; core_element_to_consider
&1e0e 69 04    ADC #&04
&1e10 85 8d    STA &8d ; core_element_to_consider
&1e12 c9 50    CMP #&50
&1e14 d0 9e    BNE &1db4 ; consider_core_elements_loop
&1e16 a9 00    LDA #&00
&1e18 85 86    STA &86 ; core_element_collected
; consider_dropping_core_element
&1e1a a5 12    LDA &12 ; pockets + 4
&1e1c f0 30    BEQ &1e4e ; not_dropping_core_element                # Is the player dropping a core element
&1e1e a0 fc    LDY #&fc
; find_empty_slot
&1e20 c8       INY
&1e21 c8       INY
&1e22 c8       INY
&1e23 c8       INY
&1e24 b9 29 05 LDA &0529,Y ; core_elements_data + 1
&1e27 29 02    AND #&02                                             # room_high of core element, &2 set if slot empty
&1e29 f0 f5    BEQ &1e20 ; find_empty_slot
&1e2b a5 7e    LDA &7e ; player_room_low                            # Put core element in slot
&1e2d 99 28 05 STA &0528,Y ; core_elements_data + 0                 # room_low of core_element
&1e30 a5 70    LDA &70 ; player_screen_address_low
&1e32 29 f8    AND #&f8
&1e34 85 8e    STA &8e ; screen_address_low
&1e36 05 7f    ORA &7f ; player_room_high
&1e38 99 29 05 STA &0529,Y ; core_elements_data + 1                 # room_high | screen_address_low of core element
&1e3b a5 71    LDA &71 ; player_screen_address_high
&1e3d 99 2a 05 STA &052a,Y ; core_elements_data + 2                 # screen_address_high of core element
&1e40 85 8f    STA &8f ; screen_address_high
&1e42 a5 12    LDA &12 ; pockets + 4
&1e44 99 2b 05 STA &052b,Y ; core_elements_data + 3                 # sprite of core element
&1e47 a2 ff    LDX #&ff                                             # White
&1e49 a0 ff    LDY #&ff                                             # EOR
&1e4b 20 b3 0b JSR &0bb3 ; plot_packed_two_colour_sprite            # Plot core element
; not_dropping_core_element
&1e4e a0 02    LDY #&02
; rotate_pockets_loop
&1e50 b9 0f 00 LDA &000f,Y ; pockets
&1e53 99 10 00 STA &0010,Y ; pockets + 1
&1e56 88       DEY
&1e57 10 f7    BPL &1e50 ; rotate_pockets_loop
&1e59 a5 86    LDA &86 ; core_element_collected
&1e5b 85 0f    STA &0f ; pockets
; skip_collecting_core_element
&1e5d a5 71    LDA &71 ; player_screen_address_high
&1e5f c5 af    CMP &af ; space_lock_entrance_screen_address_high + 2
&1e61 d0 6e    BNE &1ed1 ; not_space_lock                           # Is the player vertically aligned with space locks?
&1e63 a5 72    LDA &72 ; player_sprite
&1e65 29 03    AND #&03
&1e67 d0 68    BNE &1ed1 ; not_space_lock                           # Is the player aligned within the subtile?
&1e69 a5 70    LDA &70 ; player_screen_address_low
&1e6b a0 02    LDY #&02                                             # Right space lock
&1e6d a2 09    LDX #&09 ; new_player_sprite
&1e6f c5 ac    CMP &ac ; space_lock_entrance_screen_address_low     # Is the player entering the left space lock?
&1e71 f0 12    BEQ &1e85 ; consider_entering_space_lock
&1e73 a0 00    LDY #&00                                             # Left space lock
&1e75 a2 03    LDX #&03 ; new_player_sprite
&1e77 c5 ae    CMP &ae ; space_lock_entrance_screen_address_low  + 2
&1e79 d0 56    BNE &1ed1 ; not_space_lock                           # Is the player entering the right space lock?
&1e7b a5 7f    LDA &7f ; player_room_high
&1e7d f0 06    BEQ &1e85 ; consider_entering_space_lock
&1e7f a5 7e    LDA &7e ; player_room_low
&1e81 c9 6a    CMP #&6a                                             # The space lock in room &16a doesn't work
&1e83 f0 4c    BEQ &1ed1 ; not_space_lock                           # (it's part of a passage)
; consider_entering_space_lock
&1e85 84 86    STY &86 ; destination_space_lock
&1e87 a0 04    LDY #&04
; check_for_pass_key_loop
&1e89 88       DEY
&1e8a 30 45    BMI &1ed1 ; not_space_lock                           # Can't enter space lock without pass
&1e8c b9 0f 00 LDA &000f,Y ; pockets
&1e8f c9 09    CMP #&09 ; ITEM_PASS
&1e91 d0 f6    BNE &1e89 ; check_for_pass_loop
&1e93 8a       TXA
&1e94 48       PHA ; new_player_sprite
&1e95 a5 72    LDA &72 ; player_sprite
&1e97 20 d9 20 JSR &20d9 ; replot_player                            # Unplot player
&1e9a a2 50    LDX #&50
&1e9c a0 23    LDY #&23 ; &2350 = entering_space_lock_sound
&1e9e 20 2b 35 JSR &352b ; play_sound_using_envelope
&1ea1 68       PLA ; new_player_sprite
&1ea2 aa       TAX
&1ea3 a4 86    LDY &86 ; destination_space_lock
&1ea5 b9 ac 00 LDA &00ac,Y ; space_lock_entrance_screen_address_low # Move player to other space lock
&1ea8 85 70    STA &70 ; player_screen_address_low
&1eaa 86 72    STX &72 ; player_sprite
&1eac e0 03    CPX #&03                                             # Is this the left space lock?
&1eae d0 05    BNE &1eb5 ; skip_adjustment
&1eb0 38       SEC
&1eb1 e9 08    SBC #&08                                             # IF so, move player left four pixels
&1eb3 85 70    STA &70 ; player_screen_address_low
; skip_adjustment
&1eb5 a9 06    LDA #&06
&1eb7 85 8b    STA &8b ; count
; flash_background_loop
&1eb9 a9 03    LDA #&03
&1ebb 20 42 35 JSR &3542 ; wait_for_a_frames
&1ebe a5 91    LDA &91 ; palette + 1
&1ec0 49 07    EOR #&07                                             # Flash colour 0 of bottom section white and black
&1ec2 85 91    STA &91 ; palette + 1
&1ec4 20 00 7f JSR &7f00 ; to_set_screen_colours
&1ec7 c6 8b    DEC &8b ; count
&1ec9 d0 ee    BNE &1eb9 ; flash_background_loop
&1ecb 20 24 35 JSR &3524 ; flush_buffers
&1ece 20 d9 20 JSR &20d9 ; replot_player                            # Replot player
; not_space_lock
; check_for_player_touching_bad_subtiles
&1ed1 20 54 25 JSR &2554 ; calculate_below_player_subtile_address
&1ed4 a0 40    LDY #&40                                             # Check three subtiles vertically
&1ed6 38       SEC
&1ed7 a5 74    LDA &74 ; below_player_subtile_address_low
&1ed9 e9 40    SBC #&40                                             # Move up two subtiles
&1edb 85 8c    STA &8c ; subtile_address_low
&1edd a5 75    LDA &75 ; below_player_subtile_address_high
&1edf e9 00    SBC #&00
&1ee1 85 8d    STA &8d ; subtile_address_high
&1ee3 a5 70    LDA &70 ; player_screen_address_low
&1ee5 29 07    AND #&07
&1ee7 d0 02    BNE &1eeb ; not_group                                # If player isn't straddling group,
&1ee9 a0 20    LDY #&20                                             # only check two subtiles vertically
; not_group
&1eeb a2 01    LDX #&01                                             # Check two subtiles horizontally
&1eed a5 72    LDA &72 ; player_sprite
&1eef 29 03    AND #&03
&1ef1 f0 01    BEQ &1ef4 ; not_wide
&1ef3 e8       INX                                                  # Check three subtiles horizontally
; not_wide
&1ef4 86 8e    STX &8e ; width
; check_for_player_touching_bad_subtiles_column_loop
&1ef6 98       TYA
&1ef7 29 60    AND #&60
&1ef9 05 8e    ORA &8e ; width
&1efb a8       TAY
; check_for_player_touching_bad_subtiles_row_loop
&1efc b1 8c    LDA (&8c),Y ; subtile_address
&1efe 29 40    AND #&40 ; SUBTILE_DEADLY
&1f00 f0 04    BEQ &1f06 ; nothing_deadly_in_subtile
&1f02 a9 01    LDA #&01 ; TOUCHING_SPIKE
&1f04 85 20    STA &20 ; player_touching_death
; nothing_deadly_in_subtile
&1f06 88       DEY
&1f07 98       TYA
&1f08 29 18    AND #&18
&1f0a f0 f0    BEQ &1efc ; check_for_player_touching_bad_subtiles_row_loop
&1f0c c0 ff    CPY #&ff
&1f0e d0 e6    BNE &1ef6 ; check_for_player_touching_bad_subtiles_column_loop
&1f10 a5 20    LDA &20 ; player_touching_death
&1f12 d0 0e    BNE &1f22 ; player_is_touching_death                 # Has the played touched something deadly?
&1f14 a5 3b    LDA &3b ; player_energy_high
&1f16 f0 03    BEQ &1f1b ; player_is_out_of_energy                  # If not, is the player out of energy?
&1f18 4c da 1f JMP &1fda ; player_hasn't_died
; player_is_out_of_energy
&1f1b a9 01    LDA #&01                                             # Unplot enemies, don't update
&1f1d 20 b6 2e JSR &2eb6 ; update_enemies
&1f20 a9 0c    LDA #&0c
; player_is_touching_death
&1f22 48       PHA
&1f23 20 24 35 JSR &3524 ; flush_buffers
&1f26 20 17 0f JSR &0f17 ; play_error_sound
&1f29 68       PLA
&1f2a 0a       ASL A
&1f2b 0a       ASL A
&1f2c 85 86    STA &86 ; count
&1f2e a9 01    LDA #&01                                             # Remove fire
&1f30 85 7b    STA &7b ; fire_hit_something
&1f32 20 0f 22 JSR &220f ; update_fire                              # Unplot fire
; flash_dying_player_loop
&1f35 a9 13    LDA #&13 ; Wait for v-sync
&1f37 20 f4 ff JSR &fff4 ; OSBYTE
&1f3a 20 d9 20 JSR &20d9 ; replot_player
&1f3d c6 86    DEC &86 ; count
&1f3f 10 f4    BPL &1f35 ; flash_dying_player_loop
&1f41 a5 20    LDA &20 ; player_touching_death
&1f43 48       PHA
&1f44 f0 26    BEQ &1f6c ; skip_moving_droid                        # Keep enemies on screen if player is out of energy
&1f46 48       PHA
&1f47 a9 01    LDA #&01                                             # Unplot enemies, don't update
&1f49 20 b6 2e JSR &2eb6 ; update_enemies
&1f4c 68       PLA
&1f4d c9 02    CMP #&02 ; TOUCHING_DROID
&1f4f f0 04    BEQ &1f55 ; move_droid_to_player                     # Was the player killed by a droid?
&1f51 c9 03    CMP #&03 ; TOUCHING_NON_PATROLLING_DROID
&1f53 d0 17    BNE &1f6c ; skip_moving_droid
; move_droid_to_player
&1f55 a5 70    LDA &70 ; player_screen_address_low
&1f57 85 8e    STA &8e ; screen_address_low
&1f59 a5 71    LDA &71 ; player_screen_address_high
&1f5b 85 8f    STA &8f ; screen_address_high
&1f5d a9 00    LDA #&00
&1f5f 85 8c    STA &8c ; sprite_address_low
&1f61 a9 3c    LDA #&3c ; &3c00 = enemy_type_three_frame_1
&1f63 85 8d    STA &8d ; sprite_address_high
&1f65 a2 03    LDX #&03
&1f67 a0 02    LDY #&02
&1f69 20 26 65 JSR &6526 ; plot_unaligned_sprite                    # If so, replot that droid at player's location
; skip_moving_droid
&1f6c a5 70    LDA &70 ; player_screen_address_low
&1f6e 29 f8    AND #&f8
&1f70 8d 40 23 STA &2340 ; player_dematerialisation_data            # Set enemies_screen_address_low
&1f73 a5 71    LDA &71 ; player_screen_address_high
&1f75 8d 41 23 STA &2341 ; player_dematerialisation_data + 1        # Set enemies_screen_address_high
&1f78 a9 00    LDA #&00
&1f7a 85 8e    STA &8e ; enemy_offset
; add_player_dematerialisations_loop
&1f7c 20 40 64 JSR &6440 ; rnd
&1f7f 29 03    AND #&03
&1f81 a8       TAY
&1f82 b9 4c 23 LDA &234c,Y ; random_directions_for_player_dematerialisations
&1f85 8d 43 23 STA &2343 ; player_dematerialisation_data + 3        # Set enemies_direction
&1f88 20 40 64 JSR &6440 ; rnd
&1f8b 29 07    AND #&07
&1f8d 18       CLC
&1f8e 69 04    ADC #&04
&1f90 8d 44 23 STA &2344 ; player_dematerialisation_data + 4        # Set enemies_inertia
&1f93 a4 8e    LDY &8e ; enemy_offset
&1f95 a2 00    LDX #&00
; copy_player_dematerialisation_data_loop
&1f97 bd 40 23 LDA &2340,X ; player_dematerialisation_data
&1f9a 99 88 01 STA &0188,Y ; enemies_data
&1f9d c8       INY
&1f9e e8       INX
&1f9f e0 0c    CPX #&0c
&1fa1 d0 f4    BNE &1f97 ; copy_player_dematerialisation_data_loop
&1fa3 84 8e    STY &8e ; enemy_offset
&1fa5 c0 30    CPY #&30
&1fa7 d0 d3    BNE &1f7c ; add_player_dematerialisations_loop
&1fa9 a9 01    LDA #&01                                             # Plot player dematerialisations, don't update
&1fab 20 b6 2e JSR &2eb6 ; update_enemies
&1fae 20 24 35 JSR &3524 ; flush_buffers
&1fb1 a2 43    LDX #&43
&1fb3 a0 04    LDY #&04 ; &0443 = player_exploding_sound
&1fb5 20 2b 35 JSR &352b ; play_sound_using_envelope
&1fb8 a9 78    LDA #&78
&1fba 85 69    STA &69 ; count
; update_player_dematerialisations_loop
&1fbc a9 13    LDA #&13 ; Wait for v-sync
&1fbe 20 f4 ff JSR &fff4 ; OSBYTE
&1fc1 a9 00    LDA #&00                                             # Update and replot player dematerialisations
&1fc3 20 b6 2e JSR &2eb6 ; update_enemies
&1fc6 20 45 20 JSR &2045 ; update_scenery
&1fc9 c6 69    DEC &69 ; count
&1fcb d0 ef    BNE &1fbc ; update_player_dematerialisations_loop
&1fcd 68       PLA ; player_touching_death
&1fce f0 04    BEQ &1fd4 ; store_position                           # If the player ran out of energy,
&1fd0 c9 03    CMP #&03 ; TOUCHING_PATROLLING_DROID
&1fd2 90 03    BCC &1fd7 ; to_start_new_life                        # touched a spark or a patrolling droid,
; store_position
&1fd4 20 60 25 JSR &2560 ; store_player_entry_position              # then store their position
; to_start_new_life
&1fd7 4c ef 12 JMP &12ef ; start_new_life
; player_hasn't_died
&1fda a2 9f    LDX #&9f ; TAB
&1fdc 20 94 20 JSR &2094 ; check_for_keypress
&1fdf d0 1a    BNE &1ffb ; pause_not_pressed
&1fe1 20 24 35 JSR &3524 ; flush_buffers
&1fe4 20 e0 ff JSR &ffe0 ; OSRDCH
&1fe7 29 5f    AND #&5f                                             # Convert to uppercase
&1fe9 a2 00    LDX #&00
&1feb c9 53    CMP #&53 ; "S"
&1fed f0 05    BEQ &1ff4 ; set_sound
&1fef e8       INX
&1ff0 c9 51    CMP #&51 ; "Q"
&1ff2 d0 07    BNE &1ffb ; q_not_pressed
; set_sound
&1ff4 a0 00    LDY #&00
&1ff6 a9 d2    LDA #&d2 ; Read/Write sound suppression flag
&1ff8 20 f4 ff JSR &fff4 ; OSBYTE
; q_not_pressed
; pause_not_pressed
&1ffb a0 00    LDY #&00
; sort_enemies_by_screen_address_loop
&1ffd 84 8f    STY &8f ; enemy_offset
&1fff a6 8f    LDX &8f ; enemy_offset
; sort_enemies_by_screen_address_check_loop
&2001 bd 89 01 LDA &0189,X ; enemies_screen_address_high
&2004 d9 89 01 CMP &0189,Y ; enemies_screen_address_high
&2007 b0 02    BCS &200b ; not_lower
&2009 86 8f    STX &8f ; enemy_offset
; not_lower
&200b 18       CLC
&200c 8a       TXA
&200d 69 0c    ADC #&0c
&200f aa       TAX
&2010 e0 30    CPX #&30
&2012 30 ed    BMI &2001 ; sort_enemies_by_screen_address_check_loop
&2014 a9 0c    LDA #&0c
&2016 85 8c    STA &8c ; size
&2018 a6 8f    LDX &8f ; enemy_offset
; swap_enemy_data_loop
&201a bd 88 01 LDA &0188,X ; enemies_screen_address_low
&201d 48       PHA
&201e b9 88 01 LDA &0188,Y ; enemies_screen_address_low
&2021 9d 88 01 STA &0188,X ; enemies_screen_address_low
&2024 68       PLA
&2025 99 88 01 STA &0188,Y ; enemies_screen_address_low
&2028 c8       INY
&2029 e8       INX
&202a c6 8c    DEC &8c ; size
&202c d0 ec    BNE &201a ; swap_enemy_data_loop
&202e c0 24    CPY #&24
&2030 90 cb    BCC &1ffd ; sort_enemies_by_screen_address_loop
&2032 a2 fe    LDX #&fe ; CTRL
&2034 20 94 20 JSR &2094 ; check_for_keypress
&2037 d0 07    BNE &2040 ; to_main_game_loop
&2039 a2 8f    LDX #&8f ; ESCAPE
&203b 20 94 20 JSR &2094 ; check_for_keypress
&203e f0 03    BEQ &2043 ; escape_pressed
; to_main_game_loop
&2040 4c 03 16 JMP &1603 ; main_game_loop
; escape_pressed
&2043 18       CLC                                                  # Leave with carry clear to indicate game not completed
&2044 60       RTS

; update_scenery
&2045 20 49 21 JSR &2149 ; update_bridging_platforms
&2048 20 61 64 JSR &6461 ; update_sparks
&204b 4c ad 62 JMP &62ad ; update_pipe_arrows

; check_if_player_can_fall
&204e a0 02    LDY #&02                                             # Player is three subtiles wide
&2050 a5 72    LDA &72 ; player_sprite
&2052 29 03    AND #&03
&2054 d0 01    BNE &2057 ; player_not_straddling_subtiles
&2056 88       DEY                                                  # or two subtiles wide
; player_not_straddling_subtiles
; check_if_player_can_fall_loop
&2057 b1 74    LDA (&74),Y ; below_player_subtile_address
&2059 29 0c    AND #&0c ; SUBTILE_NO_PLAYER | SUBTILE_PIPE
&205b d0 03    BNE &2060 ; leave                                    # Leave with negative unset if obstacle
&205d 88       DEY
&205e 10 f7    BPL &2057 ; check_if_player_can_fall_loop            # Leave with negative set if no obstacle
; leave
&2060 60       RTS

; move_player_down
&2061 85 8e    STA &8e ; distance
&2063 a5 70    LDA &70 ; player_screen_address_low
&2065 29 07    AND #&07
&2067 18       CLC
&2068 65 8e    ADC &8e ; distance
&206a 29 08    AND #&08
&206c f0 1a    BEQ &2088 ; same_subtile
&206e 18       CLC
&206f a5 74    LDA &74 ; below_player_subtile_address_low
&2071 69 20    ADC #&20                                             # Move down a subtile
&2073 85 74    STA &74 ; below_player_subtile_address_low
&2075 a5 75    LDA &75 ; below_player_subtile_address_high
&2077 69 00    ADC #&00
&2079 85 75    STA &75 ; below_player_subtile_address_high
&207b 18       CLC
&207c a5 70    LDA &70 ; player_screen_address_low
&207e 69 f8    ADC #&f8
&2080 85 70    STA &70 ; player_screen_address_low
&2082 a5 71    LDA &71 ; player_screen_address_high
&2084 69 00    ADC #&00
&2086 85 71    STA &71 ; player_screen_address_high
; same_subtile
&2088 18       CLC
&2089 a5 70    LDA &70 ; player_screen_address_low
&208b 65 8e    ADC &8e ; distance
&208d 85 70    STA &70 ; player_screen_address_low
&208f 90 02    BCC &2093 ; leave
&2091 e6 71    INC &71 ; player_screen_address_high
; leave
&2093 60       RTS

; check_for_keypress
&2094 a9 81    LDA #&81 ; Scan for a particular key
&2096 a0 ff    LDY #&ff
&2098 20 f4 ff JSR &fff4 ; OSBYTE
&209b e0 ff    CPX #&ff                                             # Leave with equal if key pressed
&209d 60       RTS

; core_element_flash_colours
&209e 00 ff ; KK WW

; wipe_subtiles
&20a0 a0 00    LDY #&00
; wipe_subtiles_loop                                                # Wipe &0580 - &07ff
&20a2 a9 00    LDA #&00
&20a4 99 80 05 STA &0580,Y
&20a7 99 00 06 STA &0600,Y
&20aa 99 00 07 STA &0700,Y
&20ad c8       INY
&20ae d0 f2    BNE &20a2 ; wipe_subtiles_loop
&20b0 60       RTS

; falling_speeds
&20b1 01 00 01 00 01 02 01 02 01 02 02 03 02 03 03 04
&20c1 04

; find_bridging_platform_slot
&20c2 b9 01 04 LDA &0401,Y ; bridging_platform_data + 1
&20c5 f0 09    BEQ &20d0 ; leave
&20c7 c8       INY
&20c8 c8       INY
&20c9 98       TYA
&20ca 29 1f    AND #&1f
&20cc d0 f4    BNE &20c2 ; find_bridging_platform_slot
&20ce a9 01    LDA #&01
; leave
&20d0 60       RTS

; player_walking_sound
;     chan  vol   pitch dur
&20d1 10 00 f9 00 03 00 01 00

; replot_player
&20d9 a6 70    LDX &70 ; player_screen_address_low
&20db 86 8e    STX &8e ; screen_address_low
&20dd a6 71    LDX &71 ; player_screen_address_high
&20df 86 8f    STX &8f ; screen_address_high
&20e1 a5 72    LDA &72 ; player_sprite
&20e3 0a       ASL A
&20e4 85 8c    STA &8c ; sprite_address_low
&20e6 4a       LSR A
&20e7 65 8c    ADC &8c ; sprite_address_low
&20e9 69 08    ADC #&08
&20eb 85 8c    STA &8c ; sprite_address_low
&20ed a9 00    LDA #&00
&20ef 85 8d    STA &8d ; sprite_address_high
&20f1 a2 04    LDX #&04
; multiply_loop
&20f3 06 8c    ASL &8c ; sprite_address_low
&20f5 26 8d    ROL &8d ; sprite_address_high
&20f7 ca       DEX
&20f8 d0 f9    BNE &20f3 ; multiply_loop
&20fa a5 8d    LDA &8d ; sprite_address_high
&20fc 69 3d    ADC #&3d ; &3d00 = player_sprites - &80
&20fe 85 8d    STA &8d ; sprite_address_high
&2100 a2 03    LDX #&03                                             # 12 pixels wide
&2102 a0 02    LDY #&02                                             # 8 pixels high
&2104 20 00 63 JSR &6300 ; plot_player
&2107 a5 76    LDA &76 ; player_on_hopper
&2109 d0 c5    BNE &20d0 ; leave
&210b a5 70    LDA &70 ; player_screen_address_low
&210d 29 07    AND #&07
&210f 05 98    ORA &98 ; player_group_address_low
&2111 85 8e    STA &8e ; screen_address_low
&2113 18       CLC
&2114 a5 71    LDA &71 ; player_screen_address_high
&2116 69 02    ADC #&02
&2118 85 8f    STA &8f ; screen_address_high
&211a a5 99    LDA &99 ; hopper_sprite
&211c aa       TAX
&211d 0a       ASL A
&211e 85 8c    STA &8c ; sprite_address_low
&2120 18       CLC
&2121 8a       TXA
&2122 65 8c    ADC &8c ; sprite_address_low
&2124 85 8c    STA &8c ; sprite_address_low
&2126 a9 00    LDA #&00
&2128 85 8d    STA &8d ; sprite_address_high
&212a 06 8c    ASL &8c ; sprite_address_low
&212c 26 8d    ROL &8d ; sprite_address_high
&212e 06 8c    ASL &8c ; sprite_address_low
&2130 26 8d    ROL &8d ; sprite_address_high
&2132 06 8c    ASL &8c ; sprite_address_low
&2134 26 8d    ROL &8d ; sprite_address_high
&2136 a5 8c    LDA &8c ; sprite_address_low
&2138 69 20    ADC #&20
&213a 85 8c    STA &8c ; sprite_address_low
&213c a5 8d    LDA &8d ; sprite_address_high
&213e 69 41    ADC #&41 ; &4120 = hopper_sprites
&2140 85 8d    STA &8d ; sprite_address_high
&2142 a2 03    LDX #&03                                             # 12 pixels wide
&2144 a0 01    LDY #&01                                             # 8 pixels high
&2146 4c 26 65 JMP &6526 ; plot_unaligned_sprite                    # Plot hopper

; update_bridging_platforms
&2149 a9 00    LDA #&00
&214b 85 87    STA &87 ; bridging_platform_to_consider
; update_bridging_platforms_loop
&214d a4 87    LDY &87 ; bridging_platform_to_consider
&214f b9 00 04 LDA &0400,Y ; bridging_platform_data
&2152 85 85    STA &85 ; platform_subtile_address_low
&2154 b9 01 04 LDA &0401,Y ; bridging_platform_data + 1
&2157 85 86    STA &86 ; platform_subtile_address_high_and_ttl
&2159 29 fc    AND #&fc                                             # Top six bits are time to live
&215b f0 4c    BEQ &21a9 ; consider_next_bridging_platform          # Zero if there is no platform in this slot
&215d 38       SEC
&215e a5 86    LDA &86 ; platform_subtile_address_high_and_ttl
&2160 e9 04    SBC #&04                                             # Reduce time to live by one
&2162 85 86    STA &86 ; platform_subtile_address_high_and_ttl
&2164 29 1c    AND #&1c
&2166 c9 1c    CMP #&1c
&2168 d0 33    BNE &219d ; skip_replotting_platform                 # Replot platform every eight frames
&216a a5 86    LDA &86 ; platform_subtile_address_high_and_ttl
&216c 29 e0    AND #&e0
&216e 4a       LSR A
&216f 09 80    ORA #&80
&2171 85 8c    STA &8c ; sprite_address_low
&2173 a9 40    LDA #&40 ; &4080 = bridging_platform_sprites
&2175 85 8d    STA &8d ; sprite_address_high
&2177 20 b4 21 JSR &21b4 ; plot_bridging_platform                   # Single plot, EORs successively
&217a a5 86    LDA &86 ; platform_subtile_address_high_and_ttl
&217c 29 fc    AND #&fc
&217e c9 1c    CMP #&1c
&2180 d0 1b    BNE &219d ; platform_still_exists                    # Has the platform reached its end of life?
&2182 a5 86    LDA &86 ; platform_subtile_address_high_and_ttl
&2184 29 03    AND #&03
&2186 09 04    ORA #&04
&2188 85 86    STA &86 ; platform_subtile_address_high
&218a a0 01    LDY #&01
&218c b1 85    LDA (&85),Y ; platform_subtile_address
&218e 29 f7    AND #&f7 ; !SUBTILE_NO_PLAYER                        # Allow player to fall through empty subtiles
&2190 91 85    STA (&85),Y ; platform_subtile_address
&2192 88       DEY
&2193 b1 85    LDA (&85),Y ; platform_subtile_address
&2195 29 f7    AND #&f7 ; !SUBTILE_NO_PLAYER
&2197 91 85    STA (&85),Y ; platform_subtile_address
&2199 84 85    STY &85 ; platform_subtile_address_low               # Wipe platform data
&219b 84 86    STY &86 ; platform_subtile_address_high_and_ttl
; platform_still_exists
; skip_replotting_platform
&219d a4 87    LDY &87 ; bridging_platform_to_consider
&219f a5 85    LDA &85 ; platform_subtile_address_low
&21a1 99 00 04 STA &0400,Y; bridging_platform_data
&21a4 a5 86    LDA &86 ; platform_subtile_address_high_and_ttl
&21a6 99 01 04 STA &0401,Y ; bridging_platform_data + 1
; consider_next_bridging_platform
&21a9 e6 87    INC &87 ; bridging_platform_to_consider
&21ab e6 87    INC &87 ; bridging_platform_to_consider
&21ad a5 87    LDA &87 ; bridging_platform_to_consider
&21af c9 20    CMP #&20
&21b1 30 9a    BMI &214d ; update_bridging_platforms_loop
&21b3 60       RTS

; plot_bridging_platform
&21b4 a5 85    LDA &85 ; platform_subtile_address_low
&21b6 85 8e    STA &8e ; screen_address_low
&21b8 a5 86    LDA &86 ; platform_subtile_address_high_and_ttl
&21ba 29 03    AND #&03
&21bc 85 8f    STA &8f ; screen_address_high
&21be 06 8e    ASL &8e ; screen_address_low
&21c0 26 8f    ROL &8f ; screen_address_high
&21c2 06 8e    ASL &8e ; screen_address_low
&21c4 26 8f    ROL &8f ; screen_address_high
&21c6 06 8e    ASL &8e ; screen_address_low
&21c8 26 8f    ROL &8f ; screen_address_high
&21ca a5 8f    LDA &8f ; screen_address_high
&21cc 09 60    ORA #&60
&21ce 85 8f    STA &8f ; screen_address_high
&21d0 4c d4 65 JMP &65d4 ; plot_single_character_sprite

; plot_fire
&21d3 a5 78    LDA &78 ; fire_type
&21d5 f0 17    BEQ &21ee ; player_not_on_platform
&21d7 a9 3c    LDA #&3c ; &3cc0 = player_materialising_frame_1
&21d9 85 8d    STA &8d ; sprite_address_high
&21db a5 8e    LDA &8e ; screen_address_low
&21dd 29 10    AND #&10
&21df 49 10    EOR #&10
&21e1 85 8c    STA &8c ; sprite_address_low
&21e3 0a       ASL A
&21e4 65 8c    ADC &8c ; sprite_address_low
&21e6 69 c0    ADC #&c0
&21e8 90 0c    BCC &21f6 ; set_fire_sprite_address
&21ea e6 8d    INC &8d ; sprite_address_high
&21ec d0 08    BNE &21f6 ; set_fire_sprite_address
; player_not_on_platform
&21ee a9 41    LDA #&41 ; &4100 = fire_sprites
&21f0 85 8d    STA &8d ; sprite_address_high
&21f2 a5 8e    LDA &8e ; screen_address_low
&21f4 29 10    AND #&10
; set_fire_sprite_address
&21f6 85 8c    STA &8c ; sprite_address_low
&21f8 a5 8f    LDA &8f ; screen_address_high
&21fa 29 1f    AND #&1f
&21fc 09 60    ORA #&60
&21fe 85 8f    STA &8f ; screen_address_high
&2200 a5 8e    LDA &8e ; screen_address_low
&2202 29 f8    AND #&f8
&2204 85 8e    STA &8e ; screen_address_low
&2206 a6 78    LDX &78 ; fire_type
&2208 e8       INX
&2209 8a       TXA
&220a a8       TAY
&220b e8       INX
&220c 4c ad 65 JMP &65ad ; plot_aligned_sprite_using_eor

; update_fire
&220f a5 7d    LDA &7d ; fire_screen_address_high
&2211 30 0b    BMI &221e ; skip_unplot                              # Top bit set indicates fire not plotted
&2213 f0 19    BEQ &222e ; leave                                    # Zero if no fire
&2215 85 8f    STA &8f ; screen_address_high
&2217 a5 7c    LDA &7c ; fire_screen_address_low
&2219 85 8e    STA &8e ; screen_address_low
&221b 20 d3 21 JSR &21d3 ; plot_fire                                # unplot fire
; skip_unplot
&221e a5 7d    LDA &7d ; fire_screen_address_high
&2220 29 7f    AND #&7f                                             # Clear top bit to indicate fire needs unplotting
&2222 85 7d    STA &7d ; fire_screen_address_high
&2224 a5 7b    LDA &7b ; fire_hit_something
&2226 f0 07    BEQ &222f ; move_fire
&2228 a9 00    LDA #&00                                             # Set to zero to indicate no fire
&222a 85 7d    STA &7d ; fire_screen_address_high
&222c 85 7b    STA &7b ; fire_hit_something
; leave
&222e 60       RTS
; move_fire
&222f a5 7a    LDA &7a ; fire_direction
&2231 29 01    AND #&01 ; FIRE_LEFT
&2233 f0 09    BEQ &223e ; fire_not_moving_left
&2235 38       SEC
&2236 a5 7c    LDA &7c ; fire_screen_address_low
&2238 e9 08    SBC #&08                                             # Move left four pixels
&223a 85 7c    STA &7c ; fire_screen_address_low
&223c 90 75    BCC &22b3 ; fire_hit_left_or_right_edge_of_screen
; fire_not_moving_left
&223e a5 7a    LDA &7a ; fire_direction
&2240 29 02    AND #&02 ; FIRE_RIGHT
&2242 f0 0b    BEQ &224f ; fire_not_moving_right
&2244 18       CLC
&2245 a5 7c    LDA &7c ; fire_screen_address_low
&2247 69 08    ADC #&08                                             # Move right four pixels
&2249 85 7c    STA &7c ; fire_screen_address_low
&224b c9 f8    CMP #&f8
&224d b0 64    BCS &22b3 ; fire_hit_left_or_right_edge_of_screen
; fire_not_moving_right
&224f a5 7a    LDA &7a ; fire_direction
&2251 29 04    AND #&04 ; FIRE_UP
&2253 f0 08    BEQ &225d ; fire_not_moving_up
&2255 c6 7d    DEC &7d ; fire_screen_address_high                   # Move up eight pixels
&2257 a5 7d    LDA &7d ; fire_screen_address_high
&2259 c9 6d    CMP #&6d
&225b 90 5d    BCC &22ba ; fire_hit_top_or_bottom_edge_of_screen
; fire_not_moving_up
&225d a5 7a    LDA &7a ; fire_direction
&225f 29 08    AND #&08 ; FIRE_DOWN
&2261 f0 08    BEQ &226b ; fire_not_moving_down
&2263 e6 7d    INC &7d ; fire_screen_address_high                   # Move down eight pixels
&2265 a5 7d    LDA &7d ; fire_screen_address_high
&2267 c9 7e    CMP #&7e
&2269 b0 4f    BCS &22ba ; fire_hit_top_or_bottom_edge_of_screen
; fire_not_moving_down
&226b a6 7c    LDX &7c ; fire_screen_address_low
&226d a4 7d    LDY &7d ; fire_screen_address_high
&226f 20 e0 65 JSR &65e0 ; calculate_subtile_address_from_screen_address
&2272 a2 00    LDX #&00
&2274 86 8e    STX &8e ; fire_bounced
; check_for_obstacles_column_loop
&2276 a0 00    LDY #&00
; check_for_obstacles_row_loop
&2278 b1 6b    LDA (&6b),Y ; subtile_address
&227a 29 08    AND #&08 ; SUBTILE_NO_PLAYER
&227c 9d fe 22 STA &22fe,X ; fire_bounce_subtile_values
&227f f0 02    BEQ &2283 ; no_bounce
&2281 85 8e    STA &8e ; fire_bounced
; no_bounce
&2283 c8       INY                                                  # Move right one subtile
&2284 e8       INX
&2285 c0 02    CPY #&02
&2287 d0 ef    BNE &2278 ; check_for_obstacles_row_loop
&2289 18       CLC
&228a a5 6b    LDA &6b ; subtile_address_low
&228c 69 20    ADC #&20                                             # Move down one subtile
&228e 85 6b    STA &6b ; subtile_address_low
&2290 90 02    BCC &2294 ; skip_overflow
&2292 e6 6c    INC &6c ; subtile_address_high
; skip_overflow
&2294 8a       TXA
&2295 4a       LSR A
&2296 e9 00    SBC #&00
&2298 c5 78    CMP &78 ; fire_type                                  # Zero if fired from player, one if fired from hopper
&229a 90 da    BCC &2276 ; check_for_obstacles_column_loop          # Player fire is one subtile high, hopper fire is two
&229c a5 8e    LDA &8e ; fire_bounced
&229e d0 0b    BNE &22ab ; bounce_off_wall
&22a0 a5 7c    LDA &7c ; fire_screen_address_low
&22a2 85 8e    STA &8e ; screen_address_low
&22a4 a5 7d    LDA &7d ; fire_screen_address_high
&22a6 85 8f    STA &8f ; screen_address_high
&22a8 4c d3 21 JMP &21d3 ; plot_fire                                # Plot fire
; bounce_off_wall
&22ab ad fe 22 LDA &22fe ; fire_bounce_subtile_values
&22ae 4d ff 22 EOR &22ff ; fire_bounce_subtile_values + 1
&22b1 f0 07    BEQ &22ba ; fire_hit_top_or_bottom_edge_of_screen
; fire_hit_left_or_right_edge_of_screen
&22b3 a5 7a    LDA &7a ; fire_direction
&22b5 49 83    EOR #&83 ; FIRE_LEFT | FIRE_RIGHT | FIRE_NO_BOUNCE   # Flip direction, allow second bounce
&22b7 4c be 22 JMP &22be ; set_direction
; fire_hit_top_or_bottom_edge_of_screen
&22ba a5 7a    LDA &7a ; fire_direction
&22bc 49 8c    EOR #&8c ; FIRE_UP | FIRE_DOWN | FIRE_NO_BOUNCE      # Flip direction, allow second bounce
; set_direction
&22be 85 7a    STA &7a ; fire_direction
&22c0 29 03    AND #&03 ; FIRE_LEFT | FIRE_RIGHT
&22c2 f0 04    BEQ &22c8 ; fire_bouncing_vertically
&22c4 49 03    EOR #&03 ; FIRE_LEFT | FIRE_RIGHT
&22c6 d0 0f    BNE &22d7 ; consider_horizontal_bounce               # Always branches
; fire_bouncing_vertically
&22c8 20 40 64 JSR &6440 ; rnd
&22cb 29 03    AND #&03 ; FIRE_LEFT | FIRE_RIGHT                    # Add random left or right velocity after bounce
&22cd f0 f9    BEQ &22c8 ; fire_moving_vertically
&22cf 49 03    EOR #&03 ; FIRE_LEFT | FIRE_RIGHT
&22d1 f0 f5    BEQ &22c8 ; fire_moving_vertically
&22d3 45 7a    EOR &7a ; fire_direction
&22d5 85 7a    STA &7a ; fire_direction
; consider_horizontal_bounce
&22d7 a5 7a    LDA &7a ; fire_direction
&22d9 29 0c    AND #&0c ; FIRE_UP | FIRE_DOWN
&22db f0 04    BEQ &22e1 ; fire_moving_horizontally
&22dd 49 0c    EOR #&0c ; FIRE_UP | FIRE_DOWN
&22df d0 0f    BNE &22f0 ; remove_fire_if_bounced_twice             # Always branches
; fire_bouncing_horizontally
&22e1 20 40 64 JSR &6440 ; rnd
&22e4 29 0c    AND #&0c ; FIRE_UP | FIRE_DOWN                       # Add random up or down velocity after bounce
&22e6 f0 f9    BEQ &22e1 ; fire_bouncing_horizontally
&22e8 49 0c    EOR #&0c ; FIRE_UP | FIRE_DOWN
&22ea f0 f5    BEQ &22e1 ; fire_bouncing_horizontally
&22ec 45 7a    EOR &7a ; fire_direction
&22ee 85 7a    STA &7a ; fire_direction
; remove_fire_if_bounced_twice
&22f0 a5 7a    LDA &7a ; fire_direction                             # Top bit set if fire has already bounced
&22f2 10 03    BPL &22f7 ; remove_fire                              # Remove fire if bounced already
&22f4 4c 2f 22 JMP &222f ; move_fire
; remove_fire
&22f7 a9 00    LDA #&00
&22f9 85 7c    STA &7c ; fire_screen_address_low
&22fb 85 7d    STA &7d ; fire_screen_address_high
&22fd 60       RTS

; fire_bounce_subtile_values
&22fe 00 00 00 00

; core_room_materialisation_data
; enemy slot 0
&2302 40 ; enemies_screen_address_low
&2303 70 ; enemies_screen_address_high
&2304 04 ; enemies_type                                             # ENEMY_DEMATERIALISING
&2305 06 ; enemies_direction                                        # ENEMY_LEFT | ENEMY_DOWN
&2306 04 ; enemies_inertia
&2307 78 ; enemies_maximum_homing_cooldown
&2308 00 ; enemies_behaviour                                        # BEHAVIOUR_0: keeps moving until obstacle
&2309 00 ; enemies_move_cooldown
&230a 78 ; enemies_homing_cooldown
&230b fa ; enemies_materialisation_timer
&230c 00 ; enemies_animation
&230d 00 ; enemies_materialising
; enemy slot 1
&230e a0 ; enemies_screen_address_low
&230f 70 ; enemies_screen_address_high
&2310 04 ; enemies_type                                             # ENEMY_DEMATERIALISING
&2311 0c ; enemies_direction                                        # ENEMY_LEFT | ENEMY_UP
&2312 04 ; enemies_inertia
&2313 78 ; enemies_maximum_homing_cooldown
&2314 00 ; enemies_behaviour                                        # BEHAVIOUR_0: keeps moving until obstacle
&2315 00 ; enemies_move_cooldown
&2316 78 ; enemies_homing_cooldown
&2317 fa ; enemies_materialisation_timer
&2318 00 ; enemies_animation
&2319 00 ; enemies_materialising
; enemy slot 2
&231a 40 ; enemies_screen_address_low
&231b 78 ; enemies_screen_address_high
&231c 04 ; enemies_type                                             # ENEMY_DEMATERIALISING
&231d 03 ; enemies_direction                                        # ENEMY_RIGHT | ENEMY_DOWN
&231e 04 ; enemies_inertia
&231f 78 ; enemies_maximum_homing_cooldown
&2320 00 ; enemies_behaviour                                        # BEHAVIOUR_0: keeps moving until obstacle
&2321 00 ; enemies_move_cooldown
&2322 78 ; enemies_homing_cooldown
&2323 fa ; enemies_materialisation_timer
&2324 00 ; enemies_animation
&2325 00 ; enemies_materialising
; enemy slot 3
&2326 a0 ; enemies_screen_address_low
&2327 78 ; enemies_screen_address_high
&2328 04 ; enemies_type                                             # ENEMY_DEMATERIALISING
&2329 09 ; enemies_direction                                        # ENEMY_RIGHT | ENEMY_UP
&232a 04 ; enemies_inertia
&232b 78 ; enemies_maximum_homing_cooldown
&232c 00 ; enemies_behaviour                                        # BEHAVIOUR_0: keeps moving until obstacle
&232d 00 ; enemies_move_cooldown
&232e 78 ; enemies_homing_cooldown
&232f fa ; enemies_materialisation_timer
&2330 00 ; enemies_animation
&2331 00 ; enemies_materialising

; patrolling_droid_data
&2332 00 ; enemies_screen_address_low
&2333 7a ; enemies_screen_address_high
&2334 03 ; enemies_type                                             # ENEMY_DROID
&2335 01 ; enemies_direction                                        # ENEMY_RIGHT
&2336 0c ; enemies_inertia
&2337 1e ; enemies_maximum_homing_cooldown
&2338 00 ; enemies_behaviour                                        # BEHAVIOUR_0: keeps moving until obstacle
&2339 01 ; enemies_move_cooldown
&233a 1e ; enemies_homing_cooldown
&233b 00 ; enemies_materialisation_timer
&233c 00 ; enemies_animation
&233d 00 ; enemies_materialising

; patrolling_droid_direction_table
&233e 01 ; ENEMY_RIGHT
&233f 04 ; ENEMY_LEFT

; player_dematerialisation_data
&2340 00 ; enemies_screen_address_low
&2341 00 ; enemies_screen_address_high
&2342 04 ; enemies_type                                             # ENEMY_DEMATERIALISING
&2343 00 ; enemies_direction
&2344 00 ; enemies_inertia
&2345 78 ; enemies_maximum_homing_cooldown
&2346 00 ; enemies_behaviour                                        # BEHAVIOUR_0: keeps moving until obstacle
&2347 00 ; enemies_move_cooldown
&2348 78 ; enemies_homing_cooldown
&2349 fa ; enemies_materialisation_timer
&234a 00 ; enemies_animation
&234b 00 ; enemies_materialising

; random_directions_for_player_dematerialisations
&234c 03 ; ENEMY_RIGHT | ENEMY_DOWN
&234d 06 ; ENEMY_LEFT | ENEMY_DOWN
&234e 09 ; ENEMY_RIGHT | ENEMY_UP
&234f 0c ; ENEMY_LEFT | ENEMY_UP

; entering_space_lock_sound
; envelope
&2350 04 01 f5 eb e1 01 02 02 7e 00 00 82 82 82
;     chan  vol   pitch dur
&235e 11 00 04 00 c8 00 06 00

; plot_gates
&2366 a0 00    LDY #&00
; plot_gates_loop
&2368 b9 c3 61 LDA &61c3,Y ; gate_table
&236b c5 7e    CMP &7e ; player_room_low                            # Is the gate in this room?
&236d d0 5e    BNE &23cd ; consider_next_gate
&236f b9 c4 61 LDA &61c4,Y ; gate_table + 1
&2372 29 03    AND #&03
&2374 c5 7f    CMP &7f ; player_room_high
&2376 d0 55    BNE &23cd ; consider_next_gate
&2378 98       TYA
&2379 48       PHA
&237a b9 c4 61 LDA &61c4,Y ; gate_table + 1
&237d 29 f8    AND #&f8
&237f 85 8e    STA &8e ; screen_address_low
&2381 85 0d    STA &0d ; gate_screen_address_low
&2383 48       PHA
&2384 a9 76    LDA #&76
&2386 85 8f    STA &8f ; screen_address_high
&2388 48       PHA
&2389 a9 ab    LDA #&ab
&238b 85 8c    STA &8c ; sprite_address_low
&238d a9 61    LDA #&61 ; &61ab = gate_sprite
&238f 85 8d    STA &8d ; sprite_address_high
&2391 a2 30    LDX #&30
&2393 a0 01    LDY #&01
&2395 20 79 0b JSR &0b79 ; unpack_character
&2398 a2 02    LDX #&02                                             # 8 pixels wide
&239a a0 03    LDY #&03                                             # 24 pixels high
&239c 20 ad 65 JSR &65ad ; plot_aligned_sprite_using_eor
&239f 68       PLA
&23a0 a8       TAY
&23a1 68       PLA
&23a2 aa       TAX
&23a3 20 e0 65 JSR &65e0 ; calculate_subtile_address_from_screen_address
&23a6 86 8e    STX &8e ; subtile_address_low
&23a8 84 8f    STY &8f ; subtile_address_high
&23aa a2 03    LDX #&03
&23ac a0 00    LDY #&00
; set_subtiles_for_gate_loop
&23ae b1 8e    LDA (&8e),Y ; subtile_address
&23b0 49 18    EOR #&18 ; SUBTILE_NO_ENEMIES | SUBTILE_NO_PLAYER    # Neither player nor enemies can pass through gate
&23b2 91 8e    STA (&8e),Y ; subtile_address
&23b4 c8       INY                                                  # Move right one subtile
&23b5 b1 8e    LDA (&8e),Y ; subtile_address
&23b7 49 0c    EOR #&0c ; SUBTILE_NO_PLAYER | SUBTILE_PIPE          # Bug: should be SUBTILE_NO_ENEMIES | SUBTILE_NO_PLAYER
&23b9 91 8e    STA (&8e),Y ; subtile_address
&23bb 88       DEY                                                  # Move left one subtile
&23bc 18       CLC
&23bd a5 8e    LDA &8e ; subtile_address_low
&23bf 69 40    ADC #&40                                             # Move down two subtiles
&23c1 85 8e    STA &8e ; subtile_address_low
&23c3 90 02    BCC &23c7 ; skip_overflow
&23c5 e6 8f    INC &8f ; subtile_address_high
; skip_overflow
&23c7 ca       DEX
&23c8 d0 e4    BNE &23ae ; set_subtiles_for_gate_loop
&23ca 68       PLA
&23cb a8       TAY
&23cc 60       RTS
; consider_next_gate
&23cd c8       INY
&23ce c8       INY
&23cf c0 0a    CPY #&0a
&23d1 d0 95    BNE &2368 ; plot_gates_loop
&23d3 60       RTS

; plot_status
&23d4 a2 04    LDX #&04
&23d6 a0 00    LDY #&00
&23d8 ca       DEX
; check_score_loop
&23d9 30 5a    BMI &2435 ; skip_plotting_score
&23db b5 30    LDA &30,X ; previous_score
&23dd d5 46    CMP &46,X ; score
&23df f0 f7    BEQ &23d8 ; check_score_loop
&23e1 a2 00    LDX #&00
; poke_score_into_text_loop
&23e3 b5 46    LDA &46,X ; score                                    # Top nibble is first digit
&23e5 4a       LSR A
&23e6 4a       LSR A
&23e7 4a       LSR A
&23e8 4a       LSR A
&23e9 18       CLC
&23ea 69 61    ADC #&61 ; "a"
&23ec 99 e7 24 STA &24e7,Y ; score_text
&23ef c8       INY
&23f0 b5 46    LDA &46,X ; score
&23f2 29 0f    AND #&0f                                             # Bottom nibble is second digit
&23f4 69 61    ADC #&61 ; "a"
&23f6 99 e7 24 STA &24e7,Y ; score_text
&23f9 c8       INY
&23fa e8       INX
&23fb e0 04    CPX #&04                                             # Also pokes player_lives into lives_text
&23fd d0 e4    BNE &23e3 ; poke_score_into_text_loop
&23ff a9 0d    LDA #&0d
&2401 8d ec 24 STA &24ec ; score_text + 5                           # Separate score_text and lives_text
&2404 a9 18    LDA #&18
&2406 85 8a    STA &8a ; screen_address_low
&2408 a9 68    LDA #&68 ; &6818
&240a 85 8b    STA &8b ; screen_address_high
&240c a9 00    LDA #&00
&240e 85 87    STA &87 ; screen_offset
&2410 a9 f0    LDA #&f0                                             # Colour 2
&2412 85 89    STA &89 ; text_colour_mask
&2414 a2 e7    LDX #&e7
&2416 a0 24    LDY #&24 ; &24e7 = score_text
&2418 20 80 0a JSR &0a80 ; plot_text
&241b a9 60    LDA #&60 ; &6960
&241d 85 8a    STA &8a ; screen_address_low
&241f e6 8b    INC &8b ; screen_address_high
&2421 a9 00    LDA #&00
&2423 85 87    STA &87 ; screen_offset
&2425 a2 ed    LDX #&ed
&2427 a0 24    LDY #&24 ; &24ed = lives_text
&2429 20 80 0a JSR &0a80 ; plot_text
&242c a2 03    LDX #&03
; copy_score_loop
&242e b5 46    LDA &46,X ; score
&2430 95 30    STA &30,X ; previous_score
&2432 ca       DEX
&2433 10 f9    BPL &242e ; copy_score_loop
; skip_plotting_score
; plot_bars
&2435 a9 67    LDA #&67 ; &6788
&2437 85 8f    STA &8f ; screen_address_high
&2439 a9 88    LDA #&88
&243b 85 8e    STA &8e ; screen_address_low
&243d a9 00    LDA #&00
&243f 85 8a    STA &8a ; bar_to_plot
; plot_bars_loop
&2441 a6 8a    LDX &8a ; bar_to_plot
&2443 b5 35    LDA &35,X ; previous_player_energy_high
&2445 d5 3b    CMP &3b,X ; player_energy_high
&2447 f0 4d    BEQ &2496 ; skip_plotting_bar
&2449 a9 f0    LDA #&f0                                             # Colour 2 for energy and ammunition
&244b e0 02    CPX #&02
&244d d0 02    BNE &2451 ; not_fuel
&244f a9 ff    LDA #&ff                                             # Colour 3 for fuel
; not_fuel
&2451 85 8c    STA &8c ; bar_colour_mask
&2453 b5 3b    LDA &3b,X ; player_energy_high
&2455 c9 11    CMP #&11
&2457 90 08    BCC &2461 ; skip_overflow
&2459 a9 ff    LDA #&ff
&245b 95 3a    STA &3a,X ; player_energy_low
&245d a9 10    LDA #&10
&245f 95 3b    STA &3b,X ; player_energy_high
; skip_overflow
&2461 85 89    STA &89 ; filled_length
&2463 a9 03    LDA #&03
&2465 85 88    STA &88 ; total_length
&2467 a0 00    LDY #&00
; plot_bar_row_loop
&2469 a9 00    LDA #&00 ; KK
&246b a6 89    LDX &89 ; filled_length
&246d 30 09    BMI &2478 ; skip_table
&246f a9 ff    LDA #&ff ; WW
&2471 e0 04    CPX #&04
&2473 b0 03    BCS &2478 ; skip_table
&2475 bd ef 24 LDA &24ef,X ; partial_bar_pixel_values
; skip_table
&2478 25 8c    AND &8c ; bar_colour_mask
&247a 85 8d    STA &8d ; bar_mask
&247c a2 00    LDX #&00
; plot_bar_column_loop
&247e bd f3 24 LDA &24f3,X ; full_bar_pixel_values
&2481 25 8d    AND &8d ; bar_mask
&2483 91 8e    STA (&8e),Y ; screen_address
&2485 c8       INY
&2486 e8       INX
&2487 e0 08    CPX #&08
&2489 d0 f3    BNE &247e ; plot_bar_column_loop
&248b 38       SEC
&248c a5 89    LDA &89 ; filled_length
&248e e9 04    SBC #&04
&2490 85 89    STA &89 ; filled_length
&2492 c6 88    DEC &88 ; total_length
&2494 10 d3    BPL &2469 ; plot_bar_row_loop
; skip_plotting_bar
&2496 e6 8f    INC &8f ; screen_address_high
&2498 e6 8a    INC &8a ; bar_to_plot
&249a e6 8a    INC &8a ; bar_to_plot
&249c a5 8a    LDA &8a ; bar_to_plot
&249e c9 06    CMP #&06
&24a0 d0 9f    BNE &2441 ; plot_bars_loop
; copy_values
&24a2 a0 05    LDY #&05
; copy_values_loop
&24a4 b9 3a 00 LDA &003a,Y ; player_energy_low
&24a7 99 34 00 STA &0034,Y ; previous_player_energy_low
&24aa 88       DEY
&24ab 10 f7    BPL &24a4 ; copy_values_loop
; plot_pockets
&24ad a9 b0    LDA #&b0
&24af 85 8e    STA &8e ; screen_address_low
&24b1 a9 00    LDA #&00
&24b3 85 87    STA &87 ; pocket_to_plot
; plot_pockets_loop
&24b5 a6 87    LDX &87 ; pocket_to_plot
&24b7 b5 0f    LDA &0f,X ; pockets
&24b9 d5 13    CMP &13,X ; previous_pockets
&24bb f0 11    BEQ &24ce ; skip_pocket
&24bd a2 67    LDX #&67 
&24bf 86 8f    STX &8f ; screen_address_high
&24c1 a2 f0    LDX #&f0                                             # Colour 2
&24c3 a0 00    LDY #&00                                             # Overwrite screen
&24c5 c9 00    CMP #&00
&24c7 d0 02    BNE &24cb ; pocket_isn't_empty
&24c9 a9 08    LDA #&08 ; ITEM_EMPTY
; pocket_isn't_empty
&24cb 20 b3 0b JSR &0bb3 ; plot_packed_two_colour_sprite
; skip_pocket
&24ce 18       CLC
&24cf a5 8e    LDA &8e ; screen_address_low
&24d1 69 10    ADC #&10                                             # Move right 8 pixels
&24d3 85 8e    STA &8e ; screen_address_low
&24d5 e6 87    INC &87 ; pocket_to_plot
&24d7 c9 f0    CMP #&f0
&24d9 90 da    BCC &24b5 ; plot_pockets_loop
; copy_pockets
&24db a0 03    LDY #&03
; copy_pockets_loop
&24dd b9 0f 00 LDA &000f,Y ; pockets
&24e0 99 13 00 STA &0013,Y ; previous_pockets
&24e3 88       DEY
&24e4 10 f7    BPL &24dd ; copy_pockets_loop
&24e6 60       RTS

; score_text
&24e7 00 00 00 00 00 00

; lives_text
&24ed 00 0d

; partial_bar_pixel_values
&24ef 00 88 cc ee

; full_bar_pixel_values
&24f3 ff 00 ee ee ee 00 ff 00

; opening_gate_sound
; envelope
&24fb 04 01 fb f9 f6 04 04 04 7e 00 00 82 7e 7e
;     chan  vol   pitch dur
&2509 12 00 04 00 64 00 07 00

; collecting_sound
;     chan  vol   pitch dur
&2511 12 00 f6 00 32 00 01 00

; entering_passage_sound
; envelope
&2519 04 01 00 00 00 00 00 00 08 ec ec ec 7e 5a
;     chan  vol   pitch dur
&2527 10 00 04 00 04 00 04 00

; calculate_below_subtile_address_from_screen_address
&252f 86 8e    STX &8e ; screen_address_low
&2531 84 8f    STY &8f ; screen_address_high
&2533 a2 03    LDX #&03
; divide_by_eight_loop
&2535 46 8f    LSR &8f ; screen_address_high
&2537 66 8e    ROR &8e ; screen_address_low
&2539 ca       DEX
&253a d0 f9    BNE &2535 ; divide_by_eight_loop
&253c a5 8f    LDA &8f ; screen_address_high
&253e 29 03    AND #&03
&2540 09 04    ORA #&04
&2542 85 8f    STA &8f ; screen_address_high
&2544 18       CLC
&2545 a5 8e    LDA &8e ; screen_address_low
&2547 69 40    ADC #&40                                             # Move down two subtiles
&2549 85 8e    STA &8e ; screen_address_low
&254b aa       TAX
&254c a5 8f    LDA &8f ; screen_address_high
&254e 69 00    ADC #&00
&2550 85 8f    STA &8f ; screen_address_high
&2552 a8       TAY
&2553 60       RTS

; calculate_below_player_subtile_address
&2554 a6 70    LDX &70 ; player_screen_address_low
&2556 a4 71    LDY &71 ; player_screen_address_high
&2558 20 2f 25 JSR &252f ; calculate_below_subtile_address_from_screen_address
&255b 86 74    STX &74 ; below_player_subtile_address_low
&255d 84 75    STY &75 ; below_player_subtile_address_high
&255f 60       RTS

; store_player_entry_position
&2560 a5 70    LDA &70 ; player_screen_address_low
&2562 85 5a    STA &5a ; player_entry_screen_address_low
&2564 a5 71    LDA &71 ; player_screen_address_high
&2566 85 5b    STA &5b ; player_entry_screen_address_high
&2568 a5 72    LDA &72 ; player_sprite
&256a 85 5c    STA &5c ; player_entry_sprite
&256c a5 76    LDA &76 ; player_on_hopper
&256e 85 5d    STA &5d ; player_entry_on_platform
&2570 60       RTS

; calculate_player_group_address_and_hopper_sprite
&2571 a5 70    LDA &70 ; player_screen_address_low
&2573 29 f8    AND #&f8
&2575 85 98    STA &98 ; player_group_address_low
&2577 a5 72    LDA &72 ; player_sprite
&2579 29 03    AND #&03
&257b 85 99    STA &99 ; hopper_sprite
&257d a9 00    LDA #&00
&257f 85 45    STA &45 ; player_walking_direction
&2581 60       RTS

; set_subtiles_from_tile
&2582 a6 86    LDX &86 ; tile_offset
&2584 bd 00 04 LDA &0400,X ; room_tiles
&2587 29 3f    AND #&3f                                             # Remove any colour from tile, leaving tile type
&2589 85 8f    STA &8f ; tile_sprite
&258b 0a       ASL A
&258c 65 8f    ADC &8f ; tile_sprite
&258e 0a       ASL A
&258f 85 69    STA &69 ; offset
&2591 a0 00    LDY #&00
; set_subtiles_loop
&2593 a6 69    LDX &69 ; offset
&2595 bd 80 59 LDA &5980,X ; tile_subtile_table
&2598 29 0f    AND #&0f                                             # Bottom nibble determines type of left subtile
&259a aa       TAX
&259b bd b5 2d LDA &2db5,X ; subtile_flags_table
&259e 91 80    STA (&80),Y ; subtile_address
&25a0 c8       INY                                                  # Move right a subtile
&25a1 a6 69    LDX &69 ; offset
&25a3 bd 80 59 LDA &5980,X ; tile_subtile_table
&25a6 29 f0    AND #&f0                                             # Top nibble determines type of next subtile
&25a8 4a       LSR A
&25a9 4a       LSR A
&25aa 4a       LSR A
&25ab 4a       LSR A
&25ac aa       TAX
&25ad bd b5 2d LDA &2db5,X ; subtile_flags_table
&25b0 91 80    STA (&80),Y ; subtile_address
&25b2 c8       INY                                                  # Move right a subtile
&25b3 e6 69    INC &69 ; tile_sprite_times_six
&25b5 a5 69    LDA &69 ; tile_sprite_times_six
&25b7 29 01    AND #&01
&25b9 d0 d8    BNE &2593 ; set_subtiles_loop                        # Tile is four subtile wide
&25bb 98       TYA
&25bc 18       CLC
&25bd 69 1c    ADC #&1c                                             # Move back to left of tile, and down asubtile
&25bf a8       TAY
&25c0 c0 60    CPY #&60                                             # Tile is three subtiles high
&25c2 d0 cf    BNE &2593 ; set_subtiles_loop
&25c4 60       RTS

; calculate_room_data_address
&25c5 86 8e    STX &8e ; room_low
&25c7 84 8f    STY &8f ; room_high
&25c9 86 8c    STX &8c ; unused_room_low                            # Unnecessary code
&25cb 84 8d    STY &8d ; unused_room_high                           # Unnecessary code
&25cd 06 8e    ASL &8e ; twice_room_low
&25cf 26 8f    ROL &8f ; twice_room_high
&25d1 8a       TXA
&25d2 65 8e    ADC &8e ; twice_room_low
&25d4 85 80    STA &80 ; room_data_address_low
&25d6 98       TYA
&25d7 65 8f    ADC &8f ; twice_room_high
&25d9 85 81    STA &81 ; room_data_address_high
&25db 06 80    ASL &80 ; room_data_address_low
&25dd 26 81    ROL &81 ; room_data_address_high
&25df 06 80    ASL &80 ; room_data_address_low
&25e1 26 81    ROL &81 ; room_data_address_high
&25e3 a5 80    LDA &80 ; room_data_address_low
&25e5 69 80    ADC #&80
&25e7 85 80    STA &80 ; room_data_address_low
&25e9 a5 81    LDA &81 ; room_data_address_high
&25eb 69 41    ADC #&41 ; &4180 = room_data                         # Room data is at &4180 + 12 * room
&25ed 85 81    STA &81 ; room_data_address_high
&25ef 60       RTS

; plot_room
&25f0 86 89    STX &89 ; room_low_one                               # Two copies of each variable, identical values
&25f2 86 84    STX &84 ; room_low_two
&25f4 84 8a    STY &8a ; room_high_one
&25f6 84 85    STY &85 ; room_high_two
&25f8 a9 13    LDA #&13 ; Wait for v-sync
&25fa 20 f4 ff JSR &fff4 ; OSBYTE
&25fd a9 00    LDA #&00 ; K                                         # Hide status section
&25ff 85 93    STA &93 ; palette + 3
&2601 85 95    STA &95 ; palette + 5
&2603 85 97    STA &97 ; palette + 7
&2605 85 4d    STA &4d ; passage_screen_address_high                # No passage by default
&2607 85 59    STA &59 ; room_item_screen_address_high              # No item by default
&2609 85 af    STA &af ; space_lock_entrance_screen_address_high + 2
&260b 85 ad    STA &ad ; space_lock_entrance_screen_address_high    # No space lock by default
&260d a0 57    LDY #&57
; wipe_spark_data
&260f 99 00 01 STA &0100,Y ; spark_data                             # Wipe &0100 - &0157, i.e. spark_data, pipe_in_tile
&2612 88       DEY                                                  # and pipe_arrow_columns_status
&2613 10 fa    BPL &260f ; wipe_spark_data
&2615 20 00 7f JSR &7f00 ; to_set_screen_colours
&2618 a6 89    LDX &89 ; room_low_one
&261a a4 8a    LDY &8a ; room_high_one
&261c 20 c5 25 JSR &25c5 ; calculate_room_data_address
&261f a0 00    LDY #&00
&2621 b1 80    LDA (&80),Y ; room_data_address                      # Get first byte of room data
&2623 48       PHA
&2624 48       PHA
&2625 29 07    AND #&07                                             # Lowest three bits set type of wall
&2627 8d ab 2d STA &2dab ; room_primary_wall_type
&262a 68       PLA
&262b 29 e0    AND #&e0                                             # Top two bits set colour 2
&262d 0a       ASL A
&262e 2a       ROL A
&262f 2a       ROL A
&2630 2a       ROL A
&2631 85 95    STA &95 ; palette + 5
&2633 68       PLA
&2634 29 18    AND #&18                                             # Two of remaining three bits set colour 1 from table
&2636 4a       LSR A
&2637 4a       LSR A
&2638 4a       LSR A
&2639 aa       TAX
&263a bd b1 2d LDA &2db1,X ; room_colours_from_bits
&263d 85 93    STA &93 ; palette + 3
&263f c8       INY
&2640 b1 80    LDA (&80),Y ; room_data_address                      # Get second byte of room data
&2642 48       PHA
&2643 29 0f    AND #&0f                                             # Bottom nibble sets first extra type
&2645 8d ac 2d STA &2dac ; room_extras_types
&2648 68       PLA
&2649 4a       LSR A                                                # Top nibble sets second extra type
&264a 4a       LSR A
&264b 4a       LSR A
&264c 4a       LSR A
&264d 8d ad 2d STA &2dad ; room_extras_types + 1
&2650 a2 00    LDX #&00
&2652 a0 02    LDY #&02                                             # For third and fourth, then fifth and sixth bytes:
; get_additional_wall_types_loop
&2654 b1 80    LDA (&80),Y ; room_data_address                      # From third / fifth byte of room data:
&2656 29 c0    AND #&c0                                             # take top two bits 84...... -> ......21
&2658 0a       ASL A
&2659 2a       ROL A
&265a 2a       ROL A
&265b 85 8e    STA &8e ; tmp
&265d c8       INY
&265e b1 80    LDA (&80),Y ; room_data_address                      # From fourth / sixth byte of room data:
&2660 29 c0    AND #&c0                                             # take top two bits 84...... -> ....84..
&2662 4a       LSR A
&2663 4a       LSR A
&2664 4a       LSR A
&2665 4a       LSR A
&2666 05 8e    ORA &8e ; tmp
&2668 9d ae 2d STA &2dae,X ; room_additional_wall_types             # and combine to set first / second additional wall type
&266b c8       INY
&266c e8       INX
&266d e0 02    CPX #&02
&266f d0 e3    BNE &2654 ; get_additional_wall_types_loop
&2671 a9 00    LDA #&00                                             # No teleport by default
&2673 85 f7    STA &f7 ; teleport_screen_address_high
&2675 a9 06    LDA #&06 ; C                                         # Status section uses cyan for colour 1
&2677 85 92    STA &92 ; palette + 2
&2679 a9 03    LDA #&03 ; Y                                         # Status section uses yellow for colour 2
&267b 85 94    STA &94 ; palette + 4
&267d a9 01    LDA #&01 ; R                                         # Status section uses red for colour 2
&267f 85 96    STA &96 ; palette + 6
&2681 a9 07    LDA #&07 ; W                                         # Bottom section uses white for colour 3
&2683 85 97    STA &97 ; palette + 7
; initialise_walls
&2685 a0 06    LDY #&06                                             # Seventh through twelfth bytes of room data set walls
&2687 a2 00    LDX #&00
; initialise_walls_column_loop
&2689 b1 80    LDA (&80),Y ; room_data_address                      # Get a byte of room data for row of walls
&268b 85 8f    STA &8f ; row_bits                                   # One byte per row of eight tiles
; initialise_walls_row_loop
&268d a9 00    LDA #&00 ; TILE_EMPTY
&268f 06 8f    ASL &8f; row_bits
&2691 90 1c    BCC &26af ; set_wall                                 # Unset bit indicates empty tile
&2693 a5 85    LDA &85 ; room_high_two
&2695 d0 0e    BNE &26a5 ; use_wall
&2697 a5 84    LDA &84 ; room_low_two
&2699 c9 10    CMP #&10                                             # Rooms &000 - &00f,
&269b b0 08    BCS &26a ; use_wall
&269d c0 08    CPY #&08                                             # first two rows
&269f b0 04    BCS &26a ; use_wall
&26a1 a9 d8    LDA #&d8 ; TILE_STARS | COLOUR_3                     # use stars as wall
&26a3 d0 0a    BNE &26af ; set_wall                                 # Always branches
; use_wall
&26a5 84 8e    STY &8e ; row
&26a7 ac ab 2d LDY &2dab ; room_primary_wall_type
&26aa b9 90 2d LDA &2d90,Y ; primary_wall_tiles_table               # Get wall tile
&26ad a4 8e    LDY &8e ; row
; set_wall
&26af 9d 00 04 STA &0400,X ; room_tiles
&26b2 e8       INX
&26b3 8a       TXA
&26b4 29 07    AND #&07
&26b6 d0 d5    BNE &268d ; initialise_walls_row_loop
&26b8 c8       INY
&26b9 c0 0c    CPY #&0c
&26bb d0 cc    BNE &2689 ; initialise_walls_column_loop
; add_extras
&26bd a9 02    LDA #&02                                             # Third through sixth bytes of room data add extras
&26bf 85 8d    STA &8d ; extra_offset
; add_extras_loop
&26c1 a5 8d    LDA &8d ; extra_offset
&26c3 c9 04    CMP #&04
&26c5 30 0a    BMI &26d1 ; skip_check                               # For the second set of extras,
&26c7 a8       TAY
&26c8 b9 aa 2d LDA &2daa,Y ; room_additional_wall_types - 4
&26cb c9 0f    CMP #&0f ; NOT_ADDITIONAL_WALL                       # skip if additional wall type isn't &0f
&26cd d0 40    BNE &270f ; to_consider_next_extra                   # (rectangles will be added separately)
&26cf a5 8d    LDA &8d ; extra_offset
; skip_check
&26d1 29 01    AND #&01                                             # Third and fifth byte use first extra type
&26d3 aa       TAX                                                  # Fourth and sixth byte use second extra type
&26d4 bc ac 2d LDY &2dac,X ; room_extras_types
&26d7 b9 98 2d LDA &2d98,Y ; extra_tiles_table
&26da 85 8e    STA &8e ; extra_tile
&26dc a4 8d    LDY &8d ; extra_offset
&26de b1 80    LDA (&80),Y ; room_data_address                      # Get a byte of room data for position
&26e0 29 3f    AND #&3f                                             # Lowest six bits set position
&26e2 c9 30    CMP #&30
&26e4 b0 29    BCS &270f ; to_consider_next_extra                   # Don't add an extra if this isn't a valid tile
&26e6 aa       TAX
&26e7 a5 8d    LDA &8d ; extra_offset
&26e9 29 01    AND #&01
&26eb a8       TAY
&26ec b9 ac 2d LDA &2dac,Y ; room_extras_types
&26ef c9 06    CMP #&06 ; EXTRA_SKELETONAUT
&26f1 b0 33    BCS &2726 ; is_special_extra                         # Does the extra span several tiles?
&26f3 c9 03    CMP #&03 ; EXTRA_SPARK_HEAD
&26f5 f0 1b    BEQ &2712 ; add_spark_head                           # Or is it a spark head?
&26f7 a5 8e    LDA &8e ; extra_tile
&26f9 29 3f    AND #&3f
&26fb c9 09    CMP #&09 ; TILE_HOPPER_PAD
&26fd d0 0b    BNE &270a ; set_tile                                 # If not, and it's not a hopper pad, just set a tile
&26ff a0 00    LDY #&00                                             # Hopper pad number is on left
&2701 bd 00 04 LDA &0400,X ; room_tiles
&2704 f0 02    BEQ &2708 ; set_hopper_pad_address
&2706 a0 18    LDY #&18                                             # Hopper pad number is on right
; set_hopper_pad_address
&2708 84 64    STY &64 ; hopper_pad_screen_address_low
; set_tile
&270a a5 8e    LDA &8e ; extra_tile
&270c 9d 00 04 STA &0400,X ; room_tiles
; to_consider_next_extra
&270f 4c 39 28 JMP &2839 ; consider_next_extra
; add_spark_head
&2712 bc 00 04 LDY &0400,X ; room_tiles
&2715 a9 cc    LDA #&cc ; TILE_SPARK_HEAD | COLOUR_3
&2717 9d 00 04 STA &0400,X ; room_tiles
&271a c0 00    CPY #&00                                             # Was the tile empty?
&271c f0 f1    BEQ &270f ; to_consider_next_extra
&271e 8a       TXA
&271f 18       CLC
&2720 69 08    ADC #&08                                             # If not, add a dome below the spark head
&2722 aa       TAX
&2723 4c 2a 28 JMP &282a ; add_dome
; is_special_extra
&2726 c9 0f    CMP #&0f ; EXTRA_RECTANGLE
&2728 f0 2b    BEQ &2755 ; to_consider_next_extra
&272a c9 0e    CMP #&0e ; EXTRA_PIPE
&272c d0 03    BNE &2731 ; not_pipe
&272e 4c a9 27 JMP &27a9 ; add_pipe
; not_pipe
&2731 c9 0d    CMP #&0d ; EXTRA_PLANT
&2733 f0 30    BEQ &2765 ; add_plant
&2735 c9 06    CMP #&06 ; EXTRA_SKELETONAUT
&2737 d0 03    BNE &273c ; not_skeletonaut
&2739 4c f1 27 JMP &27f1 ; add_skeletonaut
; not_skeletonaut
&273c c9 09    CMP #&09 ; EXTRA_SPIKE
&273e d0 03    BNE &2743 ; not_spike
&2740 4c fe 27 JMP &27fe ; add_spike
; not_spike
&2743 c9 08    CMP #&08 ; EXTRA_DOME
&2745 d0 03    BNE &274a ; not_dome
&2747 4c 2a 28 JMP &282a ; add_dome
&274a c9 0a    CMP #&0a ; EXTRA_ALTAR
&274c d0 03    BNE &2751 ; not_altar
&274e 4c 0c 28 JMP &280c ; add_altar
; not_altar
&2751 c9 07    CMP #&07 ; EXTRA_SPACE_LOCK
&2753 f0 03    BEQ &2758 ; add_space_lock
; to_consider_next_extra
&2755 4c 39 28 JMP &2839 ; consider_next_extra
; add_space_lock
&2758 a9 a3    LDA #&a3 : TILE_SPACE_LOCK_LEFT | COLOUR_2
&275a 9d 00 04 STA &0400,X ; room_tiles
&275d a9 a4    LDA #&a4 ; TILE_SPACE_LOCK_RIGHT | COLOUR_2
&275f 9d 01 04 STA &0401,X ; room_tiles + 1
&2762 4c 39 28 JMP &2839 ; consider_next_extra
; add_plant
&2765 c6 8e    DEC &8e ; extra_tile                                 # Turn TILE_PLANT_BRANCHES into &1c (see &2777)
&2767 a9 1a    LDA #&1a ; TILE_PLANT_FLOWER - 1
&2769 85 8f    STA &8f ; plant_tile
&276b bd 00 04 LDA &0400,X ; room_tiles                             # Was the tile empty?
&276e d0 1d    BNE &278d ; add_downwards_plant_loop                 # If not, plant is growing downwards
&2770 a9 18    LDA #&18 ; TILE_PLANT_HEAD - 1
&2772 85 8f    STA &8f ; plant_tile
; add_upwards_plant_loop
&2774 a5 8f    LDA &8f ; plant_tile
&2776 18       CLC
&2777 69 01    ADC #&01                                             # All plant tiles are unnecessarily offset by one
&2779 9d 00 04 STA &0400,X ; room_tiles
&277c a5 8e    LDA &8e ; extra_tile
&277e 85 8f    STA &8f ; plant_tile                                 # Use TILE_PLANT_BRANCHES after first tile
&2780 8a       TXA
&2781 e9 07    SBC #&07                                             # Move up a row
&2783 aa       TAX
&2784 90 cf    BCC &2755 ; to_consider_next_extra                   # until top of screen
&2786 bd 00 04 LDA &0400,X ; room_tiles
&2789 f0 e9    BEQ &2774 ; add_upwards_plant_loop                   # or non-empty tile
&278b d0 61    BNE &27ee ; to_consider_next_extra                   # Always branches
; add_downwards_plant_loop
&278d a5 8f    LDA &8f ; plant_tile
&278f 18       CLC
&2790 69 01    ADC #&01                                             # All plant tiles are unnecessarily offset by one
&2792 9d 00 04 STA &0400,X ; room_tiles
&2795 a5 8e    LDA &8e ; extra_tile
&2797 85 8f    STA &8f ; plant_tile                                 # Use TILE_PLANT_BRANCHES after first tile
&2799 8a       TXA
&279a 18       CLC
&279b 69 08    ADC #&08                                             # Move down a row
&279d aa       TAX
&279e e0 30    CPX #&30
&27a0 b0 b3    BCS &2755 ; to_consider_next_extra                   # until bottom of screen
&27a2 bd 00 04 LDA &0400,X ; room_tiles
&27a5 f0 e6    BEQ &278d ; add_downwards_plant_loop                 # or non-empty tile
&27a7 d0 45    BNE &27ee ; to_consider_next_extra                   # Always branches
; add_pipe
&27a9 a5 95    LDA &95 ; palette + 5
&27ab 85 8b    STA &8b ; pipe_pattern
&27ad a9 00    LDA #&00                                             # Pipe is closed
&27af bc 00 04 LDY &0400,X ; room_tiles
&27b2 f0 02    BEQ &27b6 ; tile_was_empty
&27b4 a9 01    LDA #&01                                             # unless tile was empty
&27b6 85 8c    STA &8c ; pipe_state
; tile_was_empty
&27b8 a9 97    LDA #&97 ; TILE_PIPE_TOP | COLOUR_2
&27ba e0 08    CPX #&08
&27bc 10 02    BPL &27c0 ; use_top_pipe                             # If the pipe starts at the top of the screen,
&27be a5 8e    LDA &8e ; extra_tile                                 # Use TILE_PIPE_CLOSED | COLOUR_2
; use_top_pipe
&27c0 85 8f    STA &8f ; pipe_tile
; add_pipe_loop
&27c2 a5 8f    LDA &8f ; pipe_tile
&27c4 9d 00 04 STA &0400,X ; room_tiles
&27c7 a9 93    LDA #&93 ; TILE_PIPE_CLOSED | COLOUR_2
&27c9 85 8f    STA &8f ; pipe_tile
&27cb a5 8c    LDA &8c ; pipe_state
&27cd 49 01    EOR #&01                                             # Openings in pipe
&27cf 85 8c    STA &8c ; pipe_state
&27d1 d0 06    BNE &27d9 ; pipe_is_closed
&27d3 46 8b    LSR &8b ; pipe_pattern                               # use a room dependent pattern
&27d5 90 02    BCC &27d9 ; pipe_is_closed
&27d7 e6 8f    INC &8f ; pipe_tile                                  # Turn TILE_PIPE_CLOSED into TILE_PIPE_BOTH
; pipe_is_closed
&27d9 18       CLC
&27da 8a       TXA
&27db 69 08    ADC #&08                                             # Move down a row
&27dd aa       TAX
&27de a9 93    LDA #&93 ; TILE_PIPE_CLOSED | COLOUR_2
&27e0 e0 30    CPX #&30                                             # Pipe ends at bottom of screen (closed at bottom)
&27e2 b0 07    BCS &27eb ; set_tile_above_pipe
&27e4 bd 00 04 LDA &0400,X ; room_tiles
&27e7 f0 d9    BEQ &27c2 ; add_pipe_loop                            # or non-empty tile (open at bottom)
&27e9 a9 94    LDA #&94 ; TILE_PIPE_BOTH | COLOUR_2
; set_tile_above_pipe
&27eb 9d f8 03 STA &03f8,X ; room_tiles - 8
; to_consider_next_extra
&27ee 4c 39 28 JMP &2839 ; consider_next_extra
; add_skeletonaut
&27f1 a5 8e    LDA &8e ; extra_tile
&27f3 9d 00 04 STA &0400,X ; room_tiles
&27f6 18       CLC
&27f7 69 01    ADC #&01                                             # Turn TILE_SKELETONAUT_LEFT into TILE_SKELETONAUT_RIGHT
&27f9 9d 01 04 STA &0401,X ; room_tiles + 1
&27fc d0 f0    BNE &27ee ; to_consider_next_extra                   # Always branches
; add_spike
&27fe bd 08 04 LDA &0408,X ; room_tiles + 8
&2801 d0 02    BNE &2805 ; tile_is_on_wall                          # If the spike isn't above a wall,
&2803 e6 8e    INC &8e ; extra_tile                                 # Turn TILE_SPIKE into TILE_SPIKE_ON_LEDGE
; tile_is_on_wall
&2805 a5 8e    LDA &8e ; extra_tile
&2807 9d 00 04 STA &0400,X ; room_tiles
&280a d0 e2    BNE &27ee ; to_consider_next_extra                   # Always branches
; add_altar
&280c a9 e1    LDA #&e1 ; TILE_THREE_HEADED_DOME | COLOUR_3
&280e 9d 10 04 STA &0410,X ; room_tiles + 2 * 8
&2811 9d 13 04 STA &0413,X ; room_tiles + 2 * 8 + 3
&2814 9d 08 04 STA &0408,X ; room_tiles + 1 * 8
&2817 9d 0b 04 STA &040b,X ; room_tiles + 1 * 8 + 3
&281a a9 62    LDA #&62 ; TILE_WHEELED_WALL | COLOUR_3              # WWWW
&281c 9d 00 04 STA &0400,X ; room_tiles                             # D  D
&281f 9d 02 04 STA &0402,X ; room_tiles + 2                         # D  D
&2822 9d 01 04 STA &0401,X ; room_tiles + 1
&2825 9d 03 04 STA &0403,X ; room_tiles + 3
&2828 d0 0f    BNE &2839 ; consider_next_extra                      # Always branches
; add_dome
&282a bd 00 04 LDA &0400,X ; room_tiles
&282d f0 05    BEQ &2834 ; skip_pipe_top                            # If tile wasn't empty, add a pipe below the dome
&282f a9 97    LDA #&97 ; TILE_PIPE_TOP | COLOUR_2
&2831 9d 08 04 STA &0408,X ; room_tiles + 8
; skip_pipe_top
&2834 a9 d0    LDA #&d0 ; TILE_DOME | COLOUR_3
&2836 9d 00 04 STA &0400,X ; room_tiles
; consider_next_extra
&2839 e6 8d    INC &8d ; extra_offset
&283b a5 8d    LDA &8d ; extra_offset
&283d c9 06    CMP #&06
&283f f0 03    BEQ &2844 ; finished_adding_extras
&2841 4c c1 26 JMP &26c1 ; add_extras_loop
; finished_adding_extras
&2844 20 f9 2c JSR &2cf9 ; add_additional_walls
; add_teleports
&2847 a0 08    LDY #&08
; add_teleports_loop
&2849 b9 23 62 LDA &6223,Y ; teleport_data - 2                      # Seventh byte of teleport data is room_low
&284c c5 84    CMP &84 ; room_low_two
&284e d0 33    BNE &2883 ; consider_next_teleport
&2850 b9 24 62 LDA &6224,Y ; teleport_data - 1                      # Lowest bit of eighth byte is room_high
&2853 29 01    AND #&01
&2855 c5 85    CMP &85 ; room_high_two
&2857 d0 2a    BNE &2883 ; consider_next_teleport
&2859 b9 24 62 LDA &6224,Y ; teleport_data - 1                      # Remaining bits of eighth byte are tile offset
&285c 4a       LSR A
&285d aa       TAX
&285e a9 25    LDA #&25 ; TILE_TELEPORT
&2860 9d 00 04 STA &0400,X ; room_tiles
&2863 b9 22 62 LDA &6222,Y ; teleport_data - 3                      # Sixth byte of teleport data is tile on top of teleport
&2866 9d f8 03 STA &03f8,X ; room_tiles - 8                         # (always &cc TILE_SPARK_HEAD | COLOUR_3)
&2869 84 f5    STY &f5 ; room_teleport_offset
&286b 8a       TXA
&286c 29 07    AND #&07
&286e 0a       ASL A
&286f 0a       ASL A
&2870 0a       ASL A
&2871 0a       ASL A
&2872 0a       ASL A
&2873 85 f6    STA &f6 ; teleport_screen_address_low
&2875 8a       TXA
&2876 4a       LSR A
&2877 4a       LSR A
&2878 29 0e    AND #&0e
&287a 85 8e    STA &8e ; tmp
&287c 4a       LSR A
&287d 65 8e    ADC &8e ; tmp
&287f 69 6e    ADC #&6e
&2881 85 f7    STA &f7 ; teleport_screen_address_high
; consider_next_teleport
&2883 18       CLC
&2884 98       TYA
&2885 69 08    ADC #&08
&2887 a8       TAY
&2888 10 bf    BPL &2849 ; add_teleports_loop
; add_sparks
&288a a9 00    LDA #&00
&288c 85 8d    STA &8d ; tile_offset
; add_sparks_loop
&288e a6 8d    LDX &8d ; tile_offset
&2890 bd 00 04 LDA &0400,X ; room_tiles
&2893 29 3f    AND #&3f
&2895 c9 0b    CMP #&0b ; TILE_SPARK_GATE
&2897 f0 04    BEQ &289d ; has_spark
&2899 c9 0c    CMP #&0c ; TILE_SPARK_HEAD
&289b d0 52    BNE &28ef ; consider_next_tile
; has_spark
&289d 29 01    AND #&01
&289f 85 8c    STA &8c  ; spark_offset
&28a1 a0 17    LDY #&17
; move_sparks_loop
&28a3 b9 00 01 LDA &0100,Y ; sparks_screen_address_low
&28a6 99 08 01 STA &0108,Y ; sparks_screen_address_low + 8
&28a9 88       DEY
&28aa 10 f7    BPL &28a3 ; move_sparks_loop
&28ac 8a       TXA
&28ad 29 38    AND #&38
&28af 4a       LSR A
&28b0 4a       LSR A
&28b1 85 8b    STA &8b ; tmp
&28b3 4a       LSR A
&28b4 65 8b    ADC &8b ; tmp
&28b6 65 8c    ADC &8c ; spark_offset
&28b8 69 6d    ADC #&6d
&28ba 8d 01 01 STA &0101 ; sparks_screen_address_high
&28bd a8       TAY
&28be 8a       TXA
&28bf 29 07    AND #&07
&28c1 0a       ASL A
&28c2 0a       ASL A
&28c3 69 01    ADC #&01
&28c5 0a       ASL A
&28c6 0a       ASL A
&28c7 0a       ASL A
&28c8 8d 00 01 STA &0100 ; sparks_screen_address_low
&28cb aa       TAX
&28cc 20 e0 65 JSR &65e0 ; calculate_subtile_address_from_screen_address
&28cf 8e 02 01 STX &0102 ; sparks_subtile_address_low               # Set but not unused
&28d2 8c 03 01 STY &0103 ; sparks_subtile_address_high              # Set but not unused
&28d5 20 40 64 JSR &6440 ; rnd
&28d8 a5 9b    LDA &9b ; rnd_2
&28da 29 1f    AND #&1f
&28dc 8d 04 01 STA &0104 ; sparks_frame
&28df a9 2c    LDA #&2c
&28e1 8d 05 01 STA &0105 ; sparks_ignition_frame
&28e4 20 40 64 JSR &6440 ; rnd
&28e7 29 1c    AND #&1c
&28e9 18       CLC
&28ea 69 50    ADC #&50
&28ec 8d 06 01 STA &0106 ; sparks_total_frames
; consider_next_tile
&28ef e6 8d    INC &8d ; tile_offset
&28f1 a5 8d    LDA &8d ; tile_offset
&28f3 c9 30    CMP #&30
&28f5 d0 97    BNE &288e ; add_sparks_loop
; add_three_headed_domes
&28f7 a5 84    LDA &84 ; room_low_two
&28f9 c9 b0    CMP #&b0                                             # Rooms &1bb - &1bf, &1cb - &1cf, &1db - &1df,
&28fb 90 3e    BCC &293b ; skip_three_headed_domes                  # &1eb - &1ef and &1fb - &1ff have special edges
&28fd 29 0f    AND #&0f
&28ff c9 0b    CMP #&0b
&2901 90 38    BCC &293b ; skip_three_headed_domes
&2903 a5 85    LDA &85 ; room_high_two
&2905 f0 34    BEQ &293b ; skip_three_headed_domes
&2907 a0 00    LDY #&00
&2909 a9 01    LDA #&01
&290b 85 8e    STA &8e ; delta
; add_domes_loop                                                    # Replace left and right edges walls
&290d b9 00 04 LDA &0400,Y ; room_tiles
&2910 f0 09    BEQ &291b ; skip_dome
&2912 c9 c0    CMP #&c0 ; TILE_EMPTY | COLOUR_3
&2914 b0 05    BCS &291b ; skip_dome
&2916 a9 e1    LDA #&e1 ; TILE_THREE_HEADED_DOME | COLOUR_3
&2918 99 00 04 STA &0400,Y ; room_tiles
; skip_dome
&291b a5 8e    LDA &8e ; delta
&291d 49 06    EOR #&06                                             # Add 1 or 7 alternately
&291f 85 8e    STA &8e ; delta
&2921 98       TYA
&2922 18       CLC
&2923 65 8e    ADC &8e ; delta
&2925 a8       TAY
&2926 c0 30    CPY #&30
&2928 d0 e3    BNE &290d ; add_domes_loop
&292a ad 04 04 LDA &0404 ; room_tiles + 4
&292d f0 16    BEQ &2945 ; add_hexagonal_floor
&292f a0 07    LDY #&07
; add_wheeled_wall_loop
&2931 a9 62    LDA #&62 ; TILE_WHEELED_WALL | COLOUR_1              # Replace top edge walls
&2933 99 00 04 STA &0400,Y ; room_tiles
&2936 88       DEY
&2937 10 f8    BPL &2931 ; add_wheeled_wall_loop
&2939 30 0a    BMI &2945 ; add_hexagonal_floor                      # Always branches
; skip_three_headed_domes
&293b a5 84    LDA &84 ; room_low_two
&293d c9 f0    CMP #&f0                                             # Rooms &01f0 - &01ff have hexagonal floors
&293f 90 1a    BCC &295b ; skip_hexagonal_floor
&2941 a5 85    LDA &85 ; room_high_two
&2943 f0 16    BEQ &295b ; skip_hexagonal_floor
; add_hexagonal_floor
&2945 ad 2c 04 LDA &042c ; room_tiles + 5 * 8 + 4
&2948 f0 11    BEQ &295b ; skip_hexagonal_floor
&294a a0 07    LDY #&07
; add_hexagonal_floor_loop
&294c b9 28 04 LDA &0428,Y ; room_tiles + 5 * 8
&294f c9 c9    CMP #&c9 ; TILE_HOPPER_PAD | COLOUR_3
&2951 f0 05    BEQ &2958 ; skip_tile
&2953 a9 5f    LDA #&5f ; TILE_HEXAGONS | COLOUR_1
&2955 99 28 04 STA &0428,Y ; room_tiles + 5 * 8
; skip_tile
&2958 88       DEY
&2959 10 f1    BPL &294c ; add_hexagonal_floor_loop
; skip_hexagonal_floor
&295b a0 08    LDY #&08
; change_pipes_loop
&295d b9 f8 03 LDA &03f8,Y ; rooms_tiles - 8
&2960 29 3f    AND #&3f
&2962 c9 17    CMP #&17 ; TILE_PIPE_TOP
&2964 10 34    BPL &299a ; consider_next
&2966 c9 13    CMP #&13 ; TILE_PIPE_CLOSED
&2968 30 30    BMI &299a ; consider_next
&296a 48       PHA
&296b a9 01    LDA #&01
&296d 99 18 01 STA &0118,Y ; pipe_in_tile - 8
&2970 a9 02    LDA #&02 ; G                                         # Set colour 2 to green when screen has pipes
&2972 85 95    STA &95 ; palette + 5
&2974 68       PLA
&2975 c9 14    CMP #&14 ; TILE_PIPE_BOTH
&2977 d0 21    BNE &299a ; consider_next_tile
&2979 b9 f7 03 LDA &03f7,Y ; rooms_tiles - 8 - 1
&297c f0 12    BEQ &2990 ; has_left_opening
&297e b9 f9 03 LDA &03f9,Y ; rooms_tiles - 8 + 1
&2981 f0 08    BEQ &298b ; has_right_opening
&2983 a9 93    LDA #&93 ; TILE_PIPE_CLOSED | COLOUR_2
&2985 99 f8 03 STA &03f8,Y ; room_tiles - 8
&2988 4c 9a 29 JMP &299a ; consider_next_tile
; has_right_opening
&298b a9 96    LDA #&96 ; TILE_PIPE_RIGHT | COLOUR_2
&298d 99 f8 03 STA &03f8,Y ; room_tiles - 8
; has_left_opening
&2990 b9 f9 03 LDA &03f9,Y ; room_tiles - 8 + 1
&2993 f0 05    BEQ &299a ; consider_next_tile
&2995 a9 95    LDA #&95 ; TILE_PIPE_LEFT | COLOUR_2
&2997 99 f8 03 STA &03f8,Y ; room_tiles
; consider_next_tile
&299a c8       INY
&299b c0 38    CPY #&38
&299d d0 be    BNE &295d ; change_pipes_loop
; set_pipe_arrow_columns_status
&299f a9 07    LDA #&07
&29a1 85 8f    STA &8f ; column
; set_pipe_arrow_columns_status_loop
&29a3 20 40 64 JSR &6440 ; rnd
&29a6 09 10    ORA #&10
&29a8 a4 8f    LDY &8f ; column
&29aa 99 50 01 STA &0150,Y ; pipe_arrow_columns_status
&29ad c6 8f    DEC &8f ; column
&29af 10 f2    BPL &29a3 ; set_pipe_arrow_columns_status_loop
; add_sign
&29b1 a5 84    LDA &84 ; room_low_two
&29b3 c9 f4    CMP #&f4                                             # Room &1f4 has a sign
&29b5 d0 09    BNE &29c0 ; not_room_1f4
&29b7 a5 85    LDA &85 ; room_low_high
&29b9 f0 05    BEQ &29c0 ; not_room_1f4
&29bb a9 87    LDA #&87 ; TILE_SIGN | COLOUR_2
&29bd 8d 23 04 STA &0423 ; room_tiles + 4 * 8 + 3
; not_room_1f4
&29c0 a5 85    LDA &85 ; room_low_high
&29c2 d0 0b    BNE &29cf ; not_room_0ec
&29c4 a5 84    LDA &84 ; room_low_two
&29c6 c9 ec    CMP #&ec                                             # Room &0ec has a pipe next to a passage
&29c8 d0 05    BNE &29cf ; not_room_0ec
&29ca a9 94    LDA #&94 ; TILE_PIPE_BOTH | COLOUR_2                 # Make it open on both sides
&29cc 8d 25 04 STA &0425 ; room_tiles + 4 * 8 + 5
; not_room_0ec
&29cf a9 a0    LDA #&a0
&29d1 85 80    STA &80 ; subtile_address_low
&29d3 a9 05    LDA #&05 ; &05a0
&29d5 85 81    STA &81 ; subtile_address_high
&29d7 a9 00    LDA #&00
&29d9 85 82    STA &82 ; tile_screen_address_low
&29db 85 65    STA &65 ; hopper_pad_screen_address_high
&29dd 85 86    STA &86 ; tile_offset
&29df a9 6d    LDA #&6d ; &6d00
&29e1 85 83    STA &83 ; tile_screen_address_high
; plot_tiles_loop
&29e3 a4 86    LDY &86 ; tile_offset
&29e5 b9 00 04 LDA &0400,Y ; room_tiles
&29e8 29 3f    AND #&3f                                             # Bottom six bits of tile type set sprite
&29ea 85 8c    STA &8c ; sprite_address_low
&29ec b9 00 04 LDA &0400,Y ; room_tiles
&29ef 29 c0    AND #&c0                                             # Top two bits of tile type set colour
&29f1 0a       ASL A
&29f2 2a       ROL A
&29f3 2a       ROL A
&29f4 aa       TAX
&29f5 bd a7 2d LDA &2da7,X ; tile_colour_masks
&29f8 85 8b    STA &8b ; colour_mask
&29fa a9 00    LDA #&00
&29fc 85 8d    STA &8d ; sprite_address_high
&29fe a5 8c    LDA &8c ; sprite_address_low
&2a00 0a       ASL A
&2a01 65 8c    ADC &8c ; sprite_address_low
&2a03 85 8c    STA &8c ; sprite_address_low
&2a05 06 8c    ASL &8c ; sprite_address_low
&2a07 26 8d    ROL &8d ; sprite_address_high
&2a09 06 8c    ASL &8c ; sprite_address_low
&2a0b 26 8d    ROL &8d ; sprite_address_high
&2a0d 06 8c    ASL &8c ; sprite_address_low
&2a0f 26 8d    ROL &8d ; sprite_address_high
&2a11 06 8c    ASL &8c ; sprite_address_low
&2a13 26 8d    ROL &8d ; sprite_address_high
&2a15 a5 8c    LDA &8c ; sprite_address_low
&2a17 69 34    ADC #&34
&2a19 85 8c    STA &8c ; sprite_address_low
&2a1b a5 8d    LDA &8d ; sprite_address_high
&2a1d 69 5a    ADC #&5a ; &5a34 = tile_sprites - &30
&2a1f 85 8d    STA &8d ; sprite_address_high
&2a21 a5 82    LDA &82 ; tile_screen_address_low
&2a23 85 8e    STA &8e ; screen_address_low
&2a25 a5 83    LDA &83 ; tile_screen_address_high
&2a27 85 8f    STA &8f ; screen_address_high
&2a29 e0 00    CPX #&00
&2a2b d0 17    BNE &2a44 ; plot_two_colour_tile
; plot_four_colour_tile
&2a2d b9 00 04 LDA &0400,Y ; room_tiles
&2a30 d0 08    BNE &2a3a ; use_sprite
&2a32 a9 80    LDA #&80
&2a34 85 8c    STA &8c ; sprite_address_low
&2a36 a9 6c    LDA #&6c ; &6c80 = empty_sprite                      # Use an empty part of screen memory for empty tile
&2a38 85 8d    STA &8d ; sprite_address_high
; use_sprite
&2a3a a2 04    LDX #&04                                             # 16 pixels wide
&2a3c a0 03    LDY #&03                                             # 24 pixels high
&2a3e 20 00 65 JSR &6500 ; plot_aligned_sprite_using_write
&2a41 4c 88 2a JMP &2a88 ; consider_tile
; plot_two_colour_tile
&2a44 a5 8d    LDA &8d ; sprite_address_high
&2a46 8d 5a 2a STA &2a5a ; plot_sprite_address_one_high
&2a49 8d 6c 2a STA &2a6c ; plot_sprite_address_two_high
&2a4c a5 8c    LDA &8c ; sprite_address_low
&2a4e 8d 59 2a STA &2a59 ; plot_sprite_address_one_low
&2a51 8d 6b 2a STA &2a6b ; plot_sprite_address_two_low
&2a54 a2 00    LDX #&00
; plot_tile_x_loop
&2a56 a0 00    LDY #&00
; plot_tile_y_loop
&2a58 bd 00 70 LDA &7000,X
#     actually LDA plot_sprite_address_one,X
&2a5b 29 0f    AND #&0f                                             # Use bottom nibble for one row
&2a5d 85 8d    STA &8d ; sprite_address_high
&2a5f 0a       ASL A
&2a60 0a       ASL A
&2a61 0a       ASL A
&2a62 0a       ASL A
&2a63 65 8d    ADC &8d ; sprite_address_high
&2a65 25 8b    AND &8b ; colour_mask
&2a67 91 8e    STA (&8e),Y ; screen_address
&2a69 c8       INY
&2a6a bd 00 70 LDA &7000,X
#     actually LDA plot_sprite_address_two,X
&2a6d 29 f0    AND #&f0                                             # Use top nibble for next row
&2a6f 85 8d    STA &8d ; sprite_address_high
&2a71 4a       LSR A
&2a72 4a       LSR A
&2a73 4a       LSR A
&2a74 4a       LSR A
&2a75 65 8d    ADC &8d ; sprite_address_high
&2a77 25 8b    AND &8b ; colour_mask
&2a79 91 8e    STA (&8e),Y ; screen_address
&2a7b c8       INY
&2a7c e8       INX
&2a7d 8a       TXA
&2a7e 29 0f    AND #&0f                                             # 16 pixels wide
&2a80 d0 d6    BNE &2a58 ; plot_tile_y_loop
&2a82 e6 8f    INC &8f ; screen_address_high                        # Move down eight pixels
&2a84 e0 30    CPX #&30
&2a86 30 ce    BMI &2a56 ; plot_tile_x_loop                         # 24 pixels high
; consider_tile
&2a88 a4 86    LDY &86 ; tile_offset
&2a8a b9 00 04 LDA &0400,Y ; room_tiles
&2a8d 29 3f    AND #&3f
&2a8f c9 09    CMP #&09 ; TILE_HOPPER_PAD
&2a91 f0 20    BEQ &2ab3 ; is_hopper_pad
&2a93 c9 23    CMP #&23 ; TILE_SPACE_LOCK_LEFT
&2a95 f0 04    BEQ &2a9b ; is_space_lock
&2a97 c9 24    CMP #&24 ; TILE_SPACE_LOCK_RIGHT
&2a99 d0 15    BNE &2ab0 ; to_plot_next_tile_after_setting_subtiles
; is_space_lock
&2a9b 29 01    AND #&01
&2a9d 49 01    EOR #&01
&2a9f 0a       ASL A
&2aa0 a8       TAY
&2aa1 0a       ASL A
&2aa2 0a       ASL A
&2aa3 0a       ASL A
&2aa4 65 8e    ADC &8e ; scren_addess_low
&2aa6 99 ac 00 STA &00ac,Y ; space_lock_entrance_screen_address_low
&2aa9 a5 8f    LDA &8f ; screen_address_high
&2aab e9 01    SBC #&01
&2aad 99 ad 00 STA &00ad,Y ; space_lock_entrance_screen_address_high
; to_plot_next_tile_after_setting_subtiles
&2ab0 4c 46 2b JMP &2b46 ; plot_next_tile_after_setting_subtiles
; is_hopper_pad
&2ab3 38       SEC
&2ab4 a5 8f    LDA &8f ; screen_address_high
&2ab6 e9 04    SBC #&04                                             # Move up thirty two pixels
&2ab8 85 8f    STA &8f ; screen_address_high
&2aba e9 01    SBC #&01                                             # Move up eight pixels
&2abc 85 65    STA &65 ; hopper_pad_screen_address_high
&2abe a5 8e    LDA &8e ; screen_address_low
&2ac0 c9 20    CMP #&20
&2ac2 90 0a    BCC &2ace ; skip_check
&2ac4 a5 64    LDA &64 ; hopper_pad_screen_address_low              # Is the hopper pad on leftmost tile?
&2ac6 d0 06    BNE &2ace ; skip_check
&2ac8 a0 eb    LDY #&eb                                             # If not, is the tile to the left empty
&2aca b1 8e    LDA (&8e),Y ; screen_address
&2acc f0 5a    BEQ &2b28 ; skip_plotting_hopper_pad_number          # If so, don't plot hopper pad number
; skip_check
; get_modulo_three_loop
&2ace a5 7e    LDA &7e ; player_room_low                            # Number on hopper pad is room_low % 3
&2ad0 38       SEC
&2ad1 e9 03    SBC #&03
&2ad3 c9 03    CMP #&03
&2ad5 b0 fa    BCS &2ad1 ; get_modulo_three_loop
&2ad7 0a       ASL A
&2ad8 0a       ASL A
&2ad9 0a       ASL A
&2ada 85 8b    STA &8b ; sprite_offset
&2adc a4 64    LDY &64 ; hopper_pad_screen_address_low
; plot_hopper_pad_number
&2ade a6 8b    LDX &8b ; sprite_offset
; plot_hopper_pad_number_loop
&2ae0 bd 68 0a LDA &0a68,X ; hopper_pad_numbers
&2ae3 91 8e    STA (&8e),Y ; screen_address
&2ae5 c8       INY
&2ae6 e8       INX
&2ae7 98       TYA
&2ae8 29 07    AND #&07
&2aea c9 07    CMP #&07
&2aec d0 f2    BNE &2ae0 ; plot_hopper_pad_number_loop
&2aee a9 11    LDA #&11 ; colour 3 right pixel
&2af0 c0 07    CPY #&07
&2af2 f0 02    BEQ &2af6 ; set_row
&2af4 a9 88    LDA #&88 ; colour 3 left pixel
; set_row
&2af6 91 8e    STA (&8e),Y ; screen_address_low                     # Set row underneath hopper pad number
&2af8 38       SEC
&2af9 a5 80    LDA &80 ; subtile_address_low
&2afb e9 20    SBC #&20                                             # Move up one subtile
&2afd 85 8c    STA &8c ; above_subtile_address_low
&2aff a5 81    LDA &81 ; subtile_address_high
&2b01 e9 00    SBC #&00
&2b03 85 8d    STA &8d ; above_subtile_address_high
&2b05 98       TYA
&2b06 29 18    AND #&18
&2b08 4a       LSR A
&2b09 4a       LSR A
&2b0a 4a       LSR A
&2b0b a8       TAY
&2b0c a9 18    LDA #&18 ; SUBTILE_NO_ENEMIES | SUBTILE_NO_PLAYER    # Set subtile for hopper pad number
&2b0e 91 8c    STA (&8c),Y ; above_subtile_address
&2b10 c0 03    CPY #&03
&2b12 d0 14    BNE &2b28 ; skip_plotting_hopper_pad_number          # Is the hopper pad number on the right?
&2b14 a5 8e    LDA &8e ; screen_address_low
&2b16 c9 20    CMP #&20
&2b18 90 0e    BCC &2b28 ; skip_plotting_hopper_pad_number          # If so, and this isn't the leftmost tile
&2b1a c6 8f    DEC &8f ; screen_address_high
&2b1c a0 f5    LDY #&f5
&2b1e b1 8e    LDA (&8e),Y ; screen_address
&2b20 e6 8f    INC &8f ; screen_address_high
&2b22 a0 00    LDY #&00
&2b24 c9 00    CMP #&00                                             # Is the tile to the left non-empty?
&2b26 d0 b6    BNE &2ade ; plot_hopper_pad_number                   # If so, plot second hopper pad number on left
; skip_plotting_hopper_pad_number
&2b28 a5 8e    LDA &8e ; screen_address_low
&2b2a 18       CLC
&2b2b 69 08    ADC #&08
&2b2d 85 64    STA &64 ; hopper_pad_screen_address_low
&2b2f 85 8e    STA &8e ; screen_address_low
&2b31 e6 8f    INC &8f ; screen_address_high
&2b33 a5 76    LDA &76 ; player_on_hopper
&2b35 f0 0f    BEQ &2b46 ; plot_next_tile_after_setting_subtiles    # Is the player riding a hopper?
&2b37 a9 20    LDA #&20                                             # If not, plot hopper in pad
&2b39 85 8c    STA &8c ; sprite_address_low
&2b3b a9 41    LDA #&41 ; &4120 = hopper_frame_1
&2b3d 85 8d    STA &8d ; sprite_address_high
&2b3f a2 02    LDX #&02                                             # 8 pixels wide
&2b41 a0 01    LDY #&01                                             # 8 pixels high
&2b43 20 00 65 JSR &6500 ; plot_aligned_sprite_using_write
; plot_next_tile_after_setting_subtiles
&2b46 20 82 25 JSR &2582 ; set_subtiles_from_tile
&2b49 e6 86    INC &86 ; tile_offset
&2b4b 18       CLC
&2b4c a5 80    LDA &80 ; subtile_address_low
&2b4e 69 04    ADC #&04                                             # Move left four subtiles, i.e. one tile
&2b50 85 80    STA &80 ; subtile_address_low
&2b52 90 02    BCC &2b56 ; skip_overflow
&2b54 e6 81    INC &81 ; subtile_address_high
; skip_overflow
&2b56 18       CLC
&2b57 a5 82    LDA &82 ; tile_screen_address_low
&2b59 69 20    ADC #&20                                             # Move right sixteen pixels, i.e. one tile
&2b5b 85 82    STA &82 ; tile_screen_address_low
&2b5d f0 03    BEQ &2b62 ; next_row
; to_plot_tiles_loop
&2b5f 4c e3 29 JMP &29e3 ; plot_tiles_loop
; next_row
&2b62 18       CLC
&2b63 a5 80    LDA &80 ; subtile_address_low
&2b65 69 40    ADC #&40                                             # Move down two more subtiles
&2b67 85 80    STA &80 ; subtile_address_low                        # (first row was accounted for in previous loop)
&2b69 90 02    BCC &2b6d ; skip_overflow
&2b6b e6 81    INC &81 ; subtile_address_high
; skip_overflow
&2b6d 18       CLC
&2b6e a5 83    LDA &83 ; tile_screen_address_high
&2b70 69 03    ADC #&03                                             # Move down twenty four pixels
&2b72 85 83    STA &83 ; tile_screen_address_high
&2b74 c9 7f    CMP #&7f
&2b76 d0 e7    BNE &2b5f ; to_plot_tiles_loop                       # Continue until end of screen
; check_passages
&2b78 a9 26    LDA #&26
&2b7a 85 86    STA &86 ; passage_to_consider
; check_passages_loop
&2b7c a6 86    LDX &86 ; passage_to_consider
&2b7e bd d8 63 LDA &63d8,X ; passage_data                           # First byte of passage data is room_low
&2b81 c5 84    CMP &84 ; room_low_two
&2b83 d0 78    BNE &2bfd ; consider_next_passage
&2b85 bd d9 63 LDA &63d9,X ; passage_data + 1
&2b88 29 01    AND #&01                                             # Lowest bit of second byte is room_high
&2b8a c5 85    CMP &85 ; room_low_high
&2b8c d0 6f    BNE &2bfd ; consider_next_passage
&2b8e bd d9 63 LDA &63d9,X ; passage_data + 1
&2b91 4a       LSR A                                                # Remaining bits of second byte are position of passage
&2b92 20 e2 2c JSR &2ce2 ; convert_byte_to_screen_address
&2b95 8a       TXA
&2b96 29 02    AND #&02                                             # Odd passages are offset by four pixels
&2b98 0a       ASL A
&2b99 0a       ASL A
&2b9a 65 8e    ADC &8e ; screen_address_low
&2b9c 85 8e    STA &8e ; screen_address_low
&2b9e 85 4c    STA &4c ; passage_screen_address_low
&2ba0 a5 8f    LDA &8f ; screen_address_high
&2ba2 85 4d    STA &4d ; passage_screen_address_high
&2ba4 a9 6c    LDA #&6c ; &6c80 = empty_sprite                      # Use an empty part of screen memory for passage
&2ba6 85 8d    STA &8d ; sprite_address_high
&2ba8 a9 80    LDA #&80
&2baa 85 8c    STA &8c ; sprite_address_low
&2bac a2 03    LDX #&03                                             # Twelve pixels wide
&2bae a0 02    LDY #&02                                             # Sixteen pixels high
&2bb0 20 00 65 JSR &6500 ; plot_aligned_sprite_using_write
; clear_passage_subtiles
&2bb3 a6 4c    LDX &4c ; passage_screen_address_low
&2bb5 a4 4d    LDY &4d ; passage_screen_address_high
&2bb7 20 e0 65 JSR &65e0 ; calculate_subtile_address_from_screen_address
&2bba a0 00    LDY #&00
; clear_passage_subtiles_loop
&2bbc a9 00    LDA #&00
&2bbe 91 6b    STA (&6b),Y ; subtile_address                        # Set subtile to be empty
&2bc0 c8       INY
&2bc1 98       TYA
&2bc2 29 03    AND #&03
&2bc4 c9 03    CMP #&03
&2bc6 90 f4    BCC &2bbc ; clear_passage_subtiles
&2bc8 98       TYA
&2bc9 69 1c    ADC #&1c                                             # Move down one subtile
&2bcb a8       TAY
&2bcc c0 40    CPY #&40
&2bce 90 ec    BCC &2bbc ; clear_passage_subtiles
&2bd0 a5 4c    LDA &4c ; passage_screen_address_low
&2bd2 09 08    ORA #&08
&2bd4 85 4c    STA &4c ; passage_screen_address_low
&2bd6 a5 86    LDA &86 ; passage_to_consider
&2bd8 49 02    EOR #&02                                             # Consider other end of passage
&2bda aa       TAX
&2bdb bd d9 63 LDA &63d9,X  ; passage_data + 1
&2bde 4a       LSR A
&2bdf 20 e2 2c JSR &2ce2 ; convert_byte_to_screen_address
&2be2 8a       TXA
&2be3 29 02    AND #&02
&2be5 0a       ASL A
&2be6 0a       ASL A
&2be7 05 8e    ORA &8e ; screen_address_low
&2be9 85 4e    STA &4e ; passage_destination_screen_address_low
&2beb a5 8f    LDA &8f ; screen_address_high
&2bed 85 4f    STA &4f ; passage_destination_screen_address_high
&2bef bd d8 63 LDA &63d8,X ; passage_data
&2bf2 85 4b    STA &4b ; passage_destination_room_low
&2bf4 8a       TXA
&2bf5 29 02    AND #&02
&2bf7 49 02    EOR #&02
&2bf9 09 01    ORA #&01
&2bfb 85 4a    STA &4a ; passage_direction
; consider_next_passage
&2bfd c6 86    DEC &86 ; passage_to_consider
&2bff c6 86    DEC &86 ; passage_to_consider
&2c01 30 03    BMI &2c06 ; check_for_items
&2c03 4c 7c 2b JMP &2b7c ; check_passages_loop
; check_for_items
&2c06 a9 00    LDA #&00
&2c08 85 8d    STA &8d ; item_offset
&2c0a a9 00    LDA #&00
&2c0c 85 8a    STA &8a ; item_data_address_low
&2c0e a9 0c    LDA #&0c ; &0c00 = item_data
&2c10 85 8b    STA &8b ; item_data_address_high
&2c12 a2 02    LDX #&02
&2c14 a5 7e    LDA &7e ; player_room_low
&2c16 d0 04    BNE &2c1c ; check_for_items_loop
&2c18 a5 7f    LDA &7f ; player_room_high
&2c1a f0 1e    BEQ &2c3a ; to_plot_core_elements                    # No items in room &000
; check_for_items_loop
&2c1c a4 8d    LDY &8d ; item_offset
&2c1e b1 8a    LDA (&8a),Y ; item_data_address
&2c20 c5 84    CMP &84 ; room_low_two
&2c22 d0 0b    BNE &2c2f ; consider_next_item
&2c24 c8       INY
&2c25 b1 8a    LDA (&8a),Y ; item_data_address
&2c27 29 80    AND #&80
&2c29 0a       ASL A
&2c2a 2a       ROL A
&2c2b c5 85    CMP &85 ; room_low_high
&2c2d f0 0d    BEQ &2c3c ; item_is_in_room
; consider_next_item
&2c2f e6 8d    INC &8d ; item_to_consider
&2c31 e6 8d    INC &8d ; item_to_consider
&2c33 d0 e7    BNE &2c1c ; check_for_items_loop
&2c35 e6 8b    INC &8b ; item_data_address_high
&2c37 ca       DEX
&2c38 d0 e2    BNE &2c1c ; check_for_items_loop
; to_plot_core_elements
&2c3a f0 60    BEQ &2c9c ; plot_core_elements                       # Always branches
; item_is_in_room
&2c3c 86 8c    STX &8c ; unused                                     # Unnecessary code
&2c3e a5 8d    LDA &8d ; item_to_consider
&2c40 85 53    STA &53 ; room_item_data_address_low
&2c42 a5 8b    LDA &8b ; item_data_address_high
&2c44 85 54    STA &54 ; room_item_data_address_high
&2c46 b1 8a    LDA (&8a),Y ; item_data_address
&2c48 48       PHA
&2c49 29 3f    AND #&3f
&2c4b 48       PHA
&2c4c 20 e2 2c JSR &2ce2 ; convert_byte_to_screen_address
&2c4f 18       CLC
&2c50 a5 8e    LDA &8e ; screen_address_low
&2c52 69 08    ADC #&08
&2c54 85 8e    STA &8e ; screen_address_low
&2c56 46 8b    LSR &8b ; item_data_address_high
&2c58 a5 8d    LDA &8d ; item_to_consider
&2c5a 6a       ROR A
&2c5b 6a       ROR A
&2c5c 29 f0    AND #&f0
&2c5e 85 8c    STA &8c ; this_item_sprite
&2c60 a9 53    LDA #&53
&2c62 85 8d    STA &8d ; this_item_unused                           # Unnecessary code
&2c64 68       PLA
&2c65 aa       TAX
&2c66 bc 00 04 LDY &0400,X ; room_tiles
&2c69 f0 02    BEQ &2c6d ; empty_tile
&2c6b c6 8f    DEC &8f ; screen_address_high                        # Move up eight pixels if item is in spark head
; empty_tile
&2c6d 68       PLA
&2c6e 29 40    AND #&40
&2c70 0a       ASL A
&2c71 2a       ROL A
&2c72 2a       ROL A
&2c73 85 8b    STA &8b ; this_item_colour_mask
&2c75 a5 84    LDA &84 ; item_data_address_high
&2c77 29 01    AND #&01
&2c79 0a       ASL A
&2c7a 05 8b    ORA &8b ; this_item_colour_mask
&2c7c aa       TAX
&2c7d bd de 2c LDA &2cde,X ; room_item_colours
&2c80 85 8b    STA &8b ; this_item_colour_mask
&2c82 a0 04    LDY #&04
; copy_item_data_loop                                               # Set room_item_colour_mask,
&2c84 b9 8b 00 LDA &008b,Y ; this_item_data                         #     room_item_sprite,
&2c87 99 55 00 STA &0055,Y ; room_item_data                         #     room_item_unused,
&2c8a 88       DEY                                                  #     room_item_screen_address_low and
&2c8b 10 f7    BPL &2c84 ; copy_item_data_loop                      #     room_item_screen_address_high
&2c8d a5 8c    LDA &8c ; this_item_sprite
&2c8f 4a       LSR A
&2c90 4a       LSR A
&2c91 4a       LSR A
&2c92 4a       LSR A
&2c93 85 56    STA &56 ; room_item_sprite
&2c95 a6 8b    LDX &8b ; room_item_colour
&2c97 a0 ff    LDY #&ff                                             # EOR
&2c99 20 b3 0b JSR &0bb3 ; plot_packed_two_colour_sprite            # Plot item
; plot_core_elements
&2c9c a9 00    LDA #&00
&2c9e 85 88    STA &88 ; core_element_to-consider
; plot_core_elements_loop
&2ca0 a4 88    LDY &88 ; core_element_to-consider
&2ca2 b9 28 05 LDA &0528,Y ; core_elements_data + 0                 # First byte of core element data is room_low
&2ca5 c5 7e    CMP &7e ; player_room_low
&2ca7 d0 1f    BNE &2cc8 ; consider_next_core_element
&2ca9 b9 29 05 LDA &0529,Y ; core_elements_data + 1
&2cac 29 03    AND #&03                                             # Lowest two bits of second byte is room_high
&2cae c5 7f    CMP &7f ; player_room_high
&2cb0 d0 16    BNE &2cc8 ; consider_next_core_element
&2cb2 b9 29 05 LDA &0529,Y ; core_elements_data + 1
&2cb5 29 f8    AND #&f8                                             # Remaining bits of second byte are screen_address_low
&2cb7 85 8e    STA &8e ; screen_address_low
&2cb9 b9 2a 05 LDA &052a,Y ; core_elements_data + 2                 # Third byte of core element data is screen_address_high
&2cbc 85 8f    STA &8f ; screen_address_high
&2cbe b9 2b 05 LDA &052b,Y ; core_elements_data + 3                 # Fourth byte of core element data is sprite
&2cc1 a2 ff    LDX #&ff                                             # White
&2cc3 a0 ff    LDY #&ff                                             # EOR
&2cc5 20 b3 0b JSR &0bb3 ; plot_packed_two_colour_sprite            # Plot core element
; consider_next_core_element
&2cc8 18       CLC
&2cc9 a5 88    LDA &88 ; core_element_to-consider
&2ccb 69 04    ADC #&04
&2ccd 85 88    STA &88 ; core_element_to-consider
&2ccf c9 50    CMP #&50
&2cd1 d0 cd    BNE &2ca0 ; plot_core_elements_loop
; wipe_room_tiles_loop
&2cd3 a0 3f    LDY #&3f
&2cd5 a9 00    LDA #&00
&2cd7 99 00 04 STA &0400,Y ; room_tiles                             # Used for bridging platform data
&2cda 88       DEY
&2cdb 10 f8    BPL &2cd5 ; wipe_room_tiles_loop
&2cdd 60       RTS

; room_item_colours
;      3  1  2  1
&2cde ff 0f f0 0f 

; convert_byte_to_screen_address
&2ce2 48       PHA
&2ce3 4a       LSR A
&2ce4 4a       LSR A
&2ce5 4a       LSR A
&2ce6 85 8e    STA &8e ; screen_address_low
&2ce8 0a       ASL A
&2ce9 65 8e    ADC &8e ; screen_address_low
&2ceb 69 6e    ADC #&6e
&2ced 85 8f    STA &8f ; screen_address_high
&2cef 68       PLA
&2cf0 29 07    AND #&07
&2cf2 4a       LSR A
&2cf3 6a       ROR A
&2cf4 6a       ROR A
&2cf5 6a       ROR A
&2cf6 85 8e    STA &8e ; screen_address_low
&2cf8 60       RTS 

; add_additional_walls
&2cf9 a9 02    LDA #&02
&2cfb 85 8d    STA &8d ; extra_offset
; add_additional_walls_loop
&2cfd a4 8d    LDY &8d ; extra_offset
&2cff b1 80    LDA (&80),Y ; room_data_address
&2d01 29 3f    AND #&3f
&2d03 c9 30    CMP #&30
&2d05 b0 11    BCS &2d18 ; to_consider_next_more
&2d07 85 8c    STA &8c ; tile_offset
&2d09 a5 8d    LDA &8d ; extra_offset
&2d0b 29 02    AND #&02
&2d0d f0 0c    BEQ &2d1b ; is_four_or_five                          # For the first set of extras,
&2d0f a4 8d    LDY &8d ; extra_offset
&2d11 b9 aa 2d LDA &2daa,Y ; room_extras_types - 2
&2d14 c9 0f    CMP #&0f ; EXTRA_RECTANGLE                           # add rectangles if type is EXTRA_RECTANGLE
&2d16 f0 0c    BEQ &2d24 ; find_extent_of_rectangle
; to_consider_next_extra
&2d18 4c 7d 2d JMP &2d7d ; consider_next_extra
; is_four_or_five
&2d1b a4 8d    LDY &8d ; extra_offset                               # For the second set of extras,
&2d1d b9 aa 2d LDA &2daa,Y ; room_additional_wall_types - 4
&2d20 c9 0f    CMP #&0f ; NOT_ADDITIONAL_WALL                       # skip rectangles if additional wall type if &0f
&2d22 f0 f4    BEQ &2d18 ; to_consider_next_extra                   # (extras were added earlier)
; find_extent_of_rectangle
&2d24 a9 01    LDA #&01                                             # Start with a 1x1 rectangle
&2d26 85 8a    STA &8a ; width
&2d28 85 8b    STA &8b ; height
; extend_vertically
&2d2a a6 8c    LDX &8c ; tile_offset
; extend_vertically_loop                                            # Extend vertically
&2d2c bd 00 04 LDA &0400,X ; room_tiles
&2d2f d0 0d    BNE &2d3e ; find_horizontal_extent                   # Stop at non-empty tile
&2d31 e0 30    CPX #&30
&2d33 b0 09    BCS &2d3e ; find_horizontal_extent                   # Stop at bottom of screen
&2d35 e6 8b    INC &8b ; height
&2d37 8a       TXA
&2d38 69 08    ADC #&08
&2d3a aa       TAX
&2d3b 4c 2c 2d JMP &2d2c ; extend_vertically_loop
; find_horizontal_extent
&2d3e a6 8c    LDX &8c ; tile_offset
; extend_horizontally_loop                                          # Extend horizontally
&2d40 e8       INX
&2d41 8a       TXA
&2d42 29 07    AND #&07
&2d44 f0 0f    BEQ &2d55 ; skip_removing_tile                       # Stop at right edge of screen
&2d46 bd 00 04 LDA &0400,X ; room_tiles
&2d49 d0 05    BNE &2d50 ; remove_tile                              # Stop at non-empty tile
&2d4b e6 8a    INC &8a ; width
&2d4d 4c 40 2d JMP &2d40 ; extend_horizontally_loop
; remove_tile
&2d50 a9 00    LDA #&00 ; TILE_EMPTY                                # Remove the tile that marked the size of the rectangle
&2d52 9d 00 04 STA &0400,X ; room_tiles
; skip_removing_tile
&2d55 a5 8d    LDA &8d ; extra_offset
&2d57 29 01    AND #&01
&2d59 aa       TAX
&2d5a bc ae 2d LDY &2dae,X ; room_additional_wall_types
&2d5d b9 89 2d LDA &2d89,Y ; additional_wall_tiles_table
&2d60 85 88    STA &88 ; wall_tile
; add_rectangle_column_loop
&2d62 a5 8a    LDA &8a ; width
&2d64 85 89    STA &89 ; row_length
&2d66 a6 8c    LDX &8c ; tile_offset
; add_rectangle_row_loop
&2d68 a5 88    LDA &88 ; wall_tile
&2d6a 9d 00 04 STA &0400,X ; room_tiles
&2d6d e8       INX
&2d6e c6 89    DEC &89 ; row_length
&2d70 d0 f6    BNE &2d68 ; add_rectangle_row_loop
&2d72 18       CLC
&2d73 a5 8c    LDA &8c ; tile_offset
&2d75 69 08    ADC #&08
&2d77 85 8c    STA &8c ; tile_offset
&2d79 c6 8b    DEC &8b ; height
&2d7b d0 e5    BNE &2d62 ; add_rectangle_column_loop
; consider_next_extra
&2d7d e6 8d    INC &8d ; extra_offset
&2d7f a5 8d    LDA &8d ; extra_offset
&2d81 c9 06    CMP #&06
&2d83 f0 03    BEQ &2d88 ; leave
&2d85 4c fd 2c JMP &2cfd ; add_additional_walls_loop
; leave
&2d88 60       RTS

; additional_wall_tiles_table
&2d89 d8 ; &00 TILE_STARS | COLOUR_3
&2d8a 82 ; &01 TILE_WALL_WISPS | COLOUR_2
&2d8b 81 ; &02 TILE_WALL_EARTH | COLOUR_2
&2d8c 00 ; &03 TILE_EMPTY
&2d8d 00 ; &04 TILE_EMPTY
&2d8e 84 ; &05 TILE_WALL_MOLECULES | COLOUR_2
&2d8f 1d ; &06 TILE_PLANT_BRANCHES
#          &0f NOT_ADDITIONAL_WALL

; primary_wall_tiles_table
&2d90 41 ; &00 TILE_WALL_EARTH | COLOUR_1
&2d91 42 ; &01 TILE_WALL_WISPS | COLOUR_1
&2d92 43 ; &02 TILE_WALL_STONES | COLOUR_1
&2d93 44 ; &03 TILE_WALL_MOLECULES | COLOUR_1
&2d94 45 ; &04 TILE_WALL_SQUARES | COLOUR_1
&2d95 46 ; &05 TILE_WALL_RECTANGLES | COLOUR_1
&2d96 1d ; &06 TILE_PLANT_BRANCHES
&2d97 88 ; &07 TILE_WALL_TWIN | COLOUR_2

; extra_tiles_table
&2d98 c9 ; &00 EXTRA_HOPPER               : TILE_HOPPER_PAD | COLOUR_3
&2d99 ca ; &01 EXTRA_TILE_HORIZONTAL_GATE : TILE_HORIZONTAL_GATE | COLOUR_3
&2d9a cb ; &02 EXTRA_SPARK_GATE           : TILE_SPARK_GATE | COLOUR_3
&2d9b cc ; &03 EXTRA_SPARK_HEAD           : TILE_SPARK_HEAD | COLOUR_3
&2d9c cd ; &04 EXTRA_MUSHROOM             : TILE_MUSHROOM | COLOUR_3
&2d9d e1 ; &05 EXTRA_THREE_HEADED_DOME    : TILE_THREE_HEADED_DOME | COLOUR_3
&2d9e ce ; &06 EXTRA_SKELETONAUT          : TILE_SKELETONAUT_LEFT | COLOUR_3
&2d9f 46 ; &07 EXTRA_SPACE_LOCK           : TILE_WALL_RECTANGLES | COLOUR_1                 
&2da0 d0 ; &08 EXTRA_DOME                 : TILE_DOME | COLOUR_3
&2da1 d1 ; &09 EXTRA_SPIKE                : TILE_SPIKE | COLOUR_3
&2da2 00 ; &0a EXTRA_ALTAR                : TILE_EMPTY
&2da3 00 ; &0b (unused)                   : TILE_EMPTY
&2da4 00 ; &0c (unused)                   : TILE_EMPTY
&2da5 1d ; &0d EXTRA_PLANT                : TILE_PLANT_BRANCHES
&2da6 93 ; &0e EXTRA_PIPE                 : TILE_PIPE_CLOSED | COLOUR_2
#          &0f EXTRA_RECTANGLE

; tile_colour_masks
;      0  1  2  3
&2da7 00 0f f0 ff

; room_primary_wall_type
&2dab 00
; room_extras_types
&2dac 00 00
; room_additional_wall_types
&2dae 00 00

; unused
&2db0 00

; room_colours_from_bits
;      R  Y  C  M
&2db1 01 03 06 05

# Subtile flags
# =============
#     1 SUBTILE_GATE
#     2 SUBTILE_HIDE_PLAYER
#     4 SUBTILE_PIPE
#     8 SUBTILE_NO_PLAYER
#    10 SUBTILE_NO_ENEMIES
#    20 (unused)
#    40 SUBTILE_DEADLY
#    80 (unused)

; subtile_flags_table
&2db5 00 ; &00
&2db6 18 ; &01 SUBTILE_NO_ENEMIES | SUBTILE_NO_PLAYER
&2db7 40 ; &02 SUBTILE_DEADLY
&2db8 16 ; &03 SUBTILE_NO_ENEMIES | SUBTILE_PIPE | SUBTILE_HIDE_PLAYER
&2db9 19 ; &04 SUBTILE_NO_ENEMIES | SUBTILE_NO_PLAYER | SUBTILE_GATE
&2dba 1e ; &05 SUBTILE_NO_ENEMIES | SUBTILE_NO_PLAYER | SUBTILE_PIPE | SUBTILE_HIDE_PLAYER
&2dbb 14 ; &06 SUBTILE_NO_ENEMIES | SUBTILE_PIPE
&2dbc 10 ; &07 SUBTILE_NO_ENEMIES

; add_enemy
&2dbd a9 0f    LDA #&0f
&2dbf 85 8d    STA &8d ; attempts
&2dc1 a0 00    LDY #&00
; find_free_slot_loop
&2dc3 b9 89 01 LDA &0189,Y ; enemies_screen_address_high
&2dc6 f0 07    BEQ &2dcf ; found_empty_slot
&2dc8 18       CLC
&2dc9 98       TYA
&2dca 69 0c    ADC #&0c
&2dcc a8       TAY
&2dcd d0 f4    BNE &2dc3 ; find_free_slot_loop
; found_empty_slot
&2dcf 84 86    STY &86 ; enemy_offset
; try_again
&2dd1 c6 8d    DEC &8d ; attempts
&2dd3 d0 01    BNE &2dd6 ; try_to_add_enemy
&2dd5 60       RTS
; try_to_add_enemy
&2dd6 20 76 2e JSR &2e76 ; rnd_for_enemy                            # Choose a random y position
&2dd9 a5 9b    LDA &9b ; rnd_2
&2ddb 29 1f    AND #&1f
&2ddd c9 11    CMP #&11
&2ddf b0 f0    BCS &2dd1 ; try_again
&2de1 69 6d    ADC #&6d
&2de3 85 8f    STA &8f ; screen_address_high
&2de5 20 76 2e JSR &2e76 ; rnd_for_enemy                            # Choose a random x position
&2de8 a5 9b    LDA &9b ; rnd_2
&2dea 29 f8    AND #&f8
&2dec c9 f8    CMP #&f8
&2dee b0 e1    BCS &2dd1 ; try_again
&2df0 85 8e    STA &8e ; screen_address_low
&2df2 a5 8f    LDA &8f ; screen_address_high
&2df4 c9 6f    CMP #&6f
&2df6 90 0e    BCC &2e06 ; check_tile
&2df8 c9 7c    CMP #&7c
&2dfa b0 0a    BCS &2e06 ; check_tile
&2dfc a5 8e    LDA &8e ; screen_address_low
&2dfe c9 18    CMP #&18
&2e00 90 04    BCC &2e06 ; check_tile
&2e02 c9 e8    CMP #&e8
&2e04 90 cb    BCC &2dd1 ; try_again
; check_tile
&2e06 a6 8e    LDX &8e ; screen_address_low
&2e08 a4 8f    LDY &8f ; screen_address_high
&2e0a 20 89 2e JSR &2e89 ; check_if_new_enemy_can_go_in_subtiles
&2e0d b0 c2    BCS &2dd1 ; try_again                                # Check enemy can go in tile
&2e0f a5 8e    LDA &8e ; screen_address_low
&2e11 9d 88 01 STA &0188,X ; enemies_screen_address_low
&2e14 a5 8f    LDA &8f ; screen_address_high
&2e16 9d 89 01 STA &0189,X ; enemies_screen_address_high
&2e19 a9 00    LDA #&00 ; ENEMY_MATERIALISATION
&2e1b 9d 8a 01 STA &018a,X ; enemies_type
&2e1e 9d 8e 01 STA &018e,X ; enemies_behaviour                      # Enemy bounces off walls
&2e21 9d 92 01 STA &0192,X ; enemies_animation
&2e24 9d 93 01 STA &0193,X ; enemies_materialising
&2e27 a9 01    LDA #&01                                             # Make enemy move on next update
&2e29 9d 8f 01 STA &018f,X ; enemies_move_cooldown
&2e2c 9d 90 01 STA &0190,X ; enemies_homing_cooldown
&2e2f a9 14    LDA #&14                                             # Set enemy materialising
&2e31 9d 91 01 STA &0191,X ; enemies_materialisation_timer
&2e34 20 76 2e JSR &2e76 ; rnd_for_enemy                            # Choose a random diagonal direction
&2e37 29 03    AND #&03
&2e39 a8       TAY
&2e3a b9 7c 2e LDA &2e7c,Y ; random_directions
&2e3d 9d 8b 01 STA &018b,X ; enemies_direction
; choose_random_maximum_move_cooldown
&2e40 20 76 2e JSR &2e76 ; rnd_for_enemy                            # Choose a random number between 1 and 3
&2e43 29 03    AND #&03
&2e45 f0 f9    BEQ &2e40 ; choose_random_maximum_move_cooldown
&2e47 a8       TAY
&2e48 b9 7e 2e LDA &2e7e,Y ; inertias - 1                           # corresponding to an inertia of 6, 4 or 8
&2e4b 9d 8c 01 STA &018c,X ; enemies_inertia
; choose_random_maximum_homing_cooldown
&2e4e 20 76 2e JSR &2e76 ; rnd_for_enemy                            # Choose a random number between 0 and 4
&2e51 29 07    AND #&07
&2e53 c9 05    CMP #&05
&2e55 b0 f7    BCS &2e4e ; choose_random_maximum_homing_cooldown
&2e57 a8       TAY
&2e58 b9 84 2e LDA &2e84,Y ; maximum_homing_cooldowns               # corresponding to cooldown of 2, 4, 8, 16 or 32
&2e5b 9d 8d 01 STA &018d,X ; enemies_maximum_homing_cooldown
&2e5e a2 4c    LDX #&4c
&2e60 a0 60    LDY #&60 ; &604c = enemy_materialising_sound
&2e62 20 3d 35 JSR &353d ; play_sound
&2e65 c6 2f    DEC &2f ; new_enemies_needed
&2e67 a9 c0    LDA #&c0
&2e69 85 8c    STA &8c ; sprite_address_low
&2e6b a9 39    LDA #&39 ; &39c0 = enemy_materialising_frame_1
&2e6d 85 8d    STA &8d ; sprite_address_high
&2e6f a2 03    LDX #&03                                             # 12 pixels wide
&2e71 a0 02    LDY #&02                                             # 16 pixels high
&2e73 4c ad 65 JMP &65ad ; plot_aligned_sprite_using_eor

; rnd_for_enemy
&2e76 20 40 64 JSR &6440 ; rnd
&2e79 a6 86    LDX &86 ; enemy_to_consider
&2e7b 60       RTS

; random_directions
&2e7c 03 ; ENEMY_RIGHT | ENEMY_DOWN
&2e7d 0c ; ENEMY_LEFT | ENEMY_UP
&2e7e 09 ; ENEMY_RIGHT | ENEMY_UP
; intertias
&2e7f 06 ; ENEMY_LEFT | ENEMY_DOWN
&2e80 04 ; ENEMY_DOWN
&2e81 08 ; ENEMY_UP
&2e82 02 ; ENEMY_LEFT
&2e83 01 ; ENEMY_RIGHT

; maximum_homing_cooldowns
&2e84 02 04 08 10 20

; check_if_new_enemy_can_go_in_subtiles
&2e89 a2 20    LDX #&20                                             # Enemies are two subtiles high
&2e8b a0 02    LDY #&02                                             # and three subtiles wide
; check_if_enemy_can_go_in_subtiles
&2e8d 86 8a    STX &8a ; height
&2e8f 84 8b    STY &8b ; width
&2e91 a6 8e    LDX &8e ; screen_address_low
&2e93 a4 8f    LDY &8f ; screen_address_high
&2e95 20 e0 65 JSR &65e0 ; calculate_subtile_address_from_screen_address
&2e98 a6 86    LDX &86
; check_if_enemy_can_go_in_subtiles_column_loop
&2e9a a5 8b    LDA &8b ; width
&2e9c 05 8a    ORA &8a ; height
&2e9e a8       TAY
; check_if_enemy_can_go_in_subtiles_row_loop
&2e9f b1 6b    LDA (&6b),Y ; subtile_address
&2ea1 29 10    AND #&10 ; SUBTILE_NO_ENEMIES
&2ea3 d0 0f    BNE &2eb4 ; leave_with_carry_set
&2ea5 88       DEY                                                  # Move left a subtile
&2ea6 c4 8a    CPY &8a ; start_offset
&2ea8 10 f5    BPL &2e9f ; check_if_enemy_can_go_in_subtiles_row_loop
&2eaa 38       SEC
&2eab a5 8a    LDA &8a ; height
&2ead e9 20    SBC #&20                                             # Move up a subtile
&2eaf 85 8a    STA &8a ; height
&2eb1 b0 e7    BCS &2e9a ; check_if_enemy_can_go_in_subtiles_column_loop
; leave_with_carry_clear                                            # Leave with carry clear if all subtiles are passable
&2eb3 60       RTS
; leave_with_carry_set                                              # Leave with carry set if any subtile contains a wall
&2eb4 38       SEC
&2eb5 60       RTS

; update_enemies
&2eb6 85 44    STA &44 ; only_unplot_enemies
&2eb8 a9 00    LDA #&00
&2eba 85 86    STA &86 ; enemy_to_consider
&2ebc 85 20    STA &20 ; player_touching_death
; update_enemies_loop
&2ebe a6 86    LDX &86 ; enemy_to_consider
&2ec0 bd 89 01 LDA &0189,X ; enemies_screen_address_high
&2ec3 85 41    STA &41 ; enemy_previous_screen_address_high
&2ec5 c9 6d    CMP #&6d                                             # Is there an enemy in this slot?
&2ec7 90 20    BCC &2ee9 ; to_consider_next_enemy
&2ec9 a5 44    LDA &44 ; only_unplot_enemies
&2ecb d0 1f    BNE &2eec ; to_unplot_enemy_at_current_position
&2ecd bd 88 01 LDA &0188,X ; enemies_screen_address_low
&2ed0 85 40    STA &40 ; enemy_previous_screen_address_low
&2ed2 bd 8a 01 LDA &018a,X ; enemies_type
&2ed5 85 42    STA &42 ; enemy_previous_type
&2ed7 bd 92 01 LDA &0192,X ; enemies_animation
&2eda 85 43    STA &43 ; enemy_previous_animation
&2edc bd 8f 01 LDA &018f,X ; enemies_move_cooldown
&2edf e9 04    SBC #&04
&2ee1 9d 8f 01 STA &018f,X ; enemies_move_cooldown
&2ee4 90 09    BCC &2eef ; move_enemy
&2ee6 4c 9f 30 JMP &309f ; skip_moving_enemy
; to_consider_next_enemy
&2ee9 4c a0 31 JMP &31a0 ; consider_next_enemy
; to_unplot_enemy_at_current_position
&2eec 4c 89 31 JMP &3189 ; unplot_enemy_at_current_position
; move_enemy
&2eef 7d 8c 01 ADC &018c,X ; enemies_inertia
&2ef2 9d 8f 01 STA &018f,X ; enemies_move_cooldown
&2ef5 bd 89 01 LDA &0189,X ; enemies_screen_address_high
&2ef8 85 8f    STA &8f ; screen_address_high
&2efa bd 92 01 LDA &0192,X ; enemies_animation
&2efd 85 8d    STA &8d ; enemy_animation
; move_enemy_horizontally
&2eff bd 88 01 LDA &0188,X ; enemies_screen_address_low
&2f02 85 8e    STA &8e ; screen_address_low
&2f04 bd 8b 01 LDA &018b,X ; enemies_direction
&2f07 29 05    AND #&05 ; ENEMY_LEFT | ENEMY_RIGHT
&2f09 c9 01    CMP #&01 ; ENEMY_RIGHT
&2f0b f0 20    BEQ &2f2d ; move_enemy_right
&2f0d c9 04    CMP #&04 ; ENEMY_LEFT
&2f0f d0 59    BNE &2f6a ; move_enemy_vertically
; move_enemy_left
&2f11 c6 8d    DEC &8d ; enemy_animation
&2f13 10 29    BPL &2f3e ; check_horizontal_move
&2f15 a9 03    LDA #&03
&2f17 85 8d    STA &8d ; enemy_animation
&2f19 38       SEC
&2f1a a5 8e    LDA &8e ; screen_address_low                         # Move left two pixels
&2f1c e9 08    SBC #&08
&2f1e 85 8e    STA &8e ; screen_address_low
&2f20 b0 1c    BCS &2f3e ; check_horizontal_move
; flip_horizontal_direction
&2f22 bd 8b 01 LDA &018b,X ; enemies_direction
&2f25 49 05    EOR #&05 ; ENEMY_LEFT | ENEMY_RIGHT
&2f27 9d 8b 01 STA &018b,X ; enemies_direction
&2f2a 4c 6a 2f JMP &2f6a ; move_enemy_vertically
; move_enemy_right
&2f2d e6 8d    INC &8d ; enemy_animation
&2f2f a5 8d    LDA &8d ; enemy_animation
&2f31 29 03    AND #&03
&2f33 85 8d    STA &8d ; enemy_animation
&2f35 d0 07    BNE &2f3e ; check_horizontal_move
&2f37 18       CLC
&2f38 a5 8e    LDA &8e ; screen_address_low                         # Move right two pixels
&2f3a 69 08    ADC #&08
&2f3c 85 8e    STA &8e ; screen_address_low
; check_horizontal_move
&2f3e a0 02    LDY #&02                                             # Three subtiles wide
&2f40 a5 8d    LDA &8d ; enemy_animation
&2f42 d0 01    BNE &2f45 ; skip_subtile_horizontally
&2f44 88       DEY                                                  # or two, depending on animation frame
; skip_subtile_horizontally
&2f45 a2 20    LDX #&20                                             # Two subtiles high
&2f47 a5 8e    LDA &8e ; screen_address_low
&2f49 29 07    AND #&07
&2f4b f0 02    BEQ &2f4f ; skip_subtile_vertically
&2f4d a2 40    LDX #&40                                             # or four, if straddling group
&2f4f 20 8d 2e JSR &2e8d ; check_if_enemy_can_go_in_subtiles
&2f52 a6 86    LDX &86 ; enemy_to_consider
&2f54 b0 cc    BCS &2f22 ; flip_horizontal_direction                # Flip direction if enemy has hit wall
&2f56 a5 8e    LDA &8e ; screen_address_low
&2f58 c9 f0    CMP #&f0
&2f5a 90 04    BCC &2f60 ; set_animation
&2f5c a5 8d    LDA &8d ; enemy_animation
&2f5e d0 c2    BNE &2f22 ; flip_direction                           # Flip direction if enemy has hit edge of screen
; set_animation
&2f60 a5 8d    LDA &8d ; enemy_animation
&2f62 9d 92 01 STA &0192,X ; enemies_animation
&2f65 a5 8e    LDA &8e ; screen_address_low
&2f67 9d 88 01 STA &0188,X ; enemies_screen_address_low
; move_enemy_vertically
&2f6a bd 88 01 LDA &0188,X ; enemies_screen_address_low
&2f6d 85 8e    STA &8e ; screen_address_low
&2f6f bd 89 01 LDA &0189,X ; enemies_screen_address_high
&2f72 85 8f    STA &8f ; screen_address_high
&2f74 bd 8b 01 LDA &018b,X ; enemies_direction
&2f77 29 0a    AND #&0a ; ENEMY_DOWN | ENEMY_UP
&2f79 c9 02    CMP #&02 ; ENEMY_DOWN
&2f7b f0 25    BEQ &2fa2 ; move_enemy_down
&2f7d c9 08    CMP #&08 ; ENEMY_UP
&2f7f d0 67    BNE &2fe8 ; skip_vertical_move
; move_enemy_up
&2f81 a5 8e    LDA &8e ; screen_address_low                         # Move up two pixels
&2f83 e9 02    SBC #&02
&2f85 85 8e    STA &8e ; screen_address_low
&2f87 29 06    AND #&06
&2f89 c9 06    CMP #&06
&2f8b 90 28    BCC &2fb5 ; check_vertical_move
&2f8d a5 8e    LDA &8e ; screen_address_low
&2f8f 69 07    ADC #&07
&2f91 85 8e    STA &8e ; screen_address_low
&2f93 c6 8f    DEC &8f ; screen_address_high
&2f95 d0 1e    BNE &2fb5 ; check_vertical_move
; flip_vertical_direction
&2f97 bd 8b 01 LDA &018b,X ; enemies_direction
&2f9a 49 0a    EOR #&0a ; ENEMY_DOWN | ENEMY_UP
&2f9c 9d 8b 01 STA &018b,X ; enemies_direction
&2f9f 4c e8 2f JMP &2fe8 ; skip_vertical_move
; move_enemy_down
&2fa2 18       CLC
&2fa3 a5 8e    LDA &8e ; screen_address_low                         # Move down two pixels
&2fa5 69 02    ADC #&02
&2fa7 85 8e    STA &8e ; screen_address_low
&2fa9 29 07    AND #&07
&2fab d0 08    BNE &2fb5 ; check_vertical_move
&2fad a5 8e    LDA &8e ; screen_address_low
&2faf e9 07    SBC #&07
&2fb1 85 8e    STA &8e ; screen_address_low
&2fb3 e6 8f    INC &8f ; screen_address_high
; check_vertical_move
&2fb5 a0 01    LDY #&01                                             # Two subtiles wide
&2fb7 bd 92 01 LDA &0192,X ; enemies_animation
&2fba f0 01    BEQ &2fbd ; skip_horizontal_subtile
&2fbc c8       INY                                                  # or three, depending on animation frame
; skip_horizontal_subtile
&2fbd a2 20    LDX #&20                                             # Two subtiles high
&2fbf a5 8e    LDA &8e ; screen_address_low
&2fc1 29 07    AND #&07
&2fc3 f0 02    BEQ &2fc7 ; skip_vertical_subtile
&2fc5 a2 40    LDX #&40                                             # or three, if straddling group
; skip_vertical_subtile
&2fc7 20 8d 2e JSR &2e8d ; check_if_enemy_can_go_in_subtiles
&2fca a6 86    LDX &86 ; enemy_to_consider
&2fcc b0 c9    BCS &2f97 ; flip_vertical_direction                  # Flip direction if enemy has hit wall
&2fce a5 8f    LDA &8f ; screen_address_high
&2fd0 c9 6d    CMP #&6d
&2fd2 90 c3    BCC &2f97 ; flip_vertical_direction                  # Flip direction if enemy has hit top of screen
&2fd4 c9 7d    CMP #&7d
&2fd6 90 06    BCC &2fde ; skip_flip_check
&2fd8 a5 8e    LDA &8e
&2fda 29 07    AND #&07
&2fdc d0 b9    BNE &2f97 ; flip_vertical_direction                  # Flip direction if enemy has hit bottom of screen
; skip_flip_check
&2fde a5 8e    LDA &8e ; screen_address_low
&2fe0 9d 88 01 STA &0188,X ; enemies_screen_address_low
&2fe3 a5 8f    LDA &8f ; screen_address_high
&2fe5 9d 89 01 STA &0189,X ; enemies_screen_address_high
; skip_vertical_move
&2fe8 bd 93 01 LDA &0193,X ; enemies_materialising
&2feb d0 2c    BNE &3019 ; skip_materialisation
&2fed bd 91 01 LDA &0191,X ; enemies_materialisation_timer
&2ff0 f0 27    BEQ &3019 ; skip_materialisation
&2ff2 de 91 01 DEC &0191,X ; enemies_materialisation_timer
&2ff5 d0 22    BNE &3019 ; skip_materialisation
; set_random_behaviour
&2ff7 20 76 2e JSR &2e76 ; rnd_for_enemy                            # Get random number between 0 and 4 for behaviour
&2ffa c9 05    CMP #&05
&2ffc b0 f9    BCS &2ff7 ; set_random_behaviour
&2ffe 9d 8e 01 STA &018e,X ; enemies_behaviour
&3001 c9 04    CMP #&04 ; BEHAVIOUR_4                               # If BEHAVIOUR_4, enemy is a droid
&3003 d0 09    BNE &300e ; not_droid
&3005 20 76 2e JSR &2e76 ; rnd_for_enemy                            # Make droids half as likely to occur
&3008 29 02    AND #&02
&300a f0 eb    BEQ &2ff7 ; set_random_behaviour
&300c d0 05    BNE &3013 ; set_enemy_type                           # Always branches
; not_droid
&300e 20 76 2e JSR &2e76 ; rnd_for_enemy                            # Choose random enemy type
&3011 29 01    AND #&01
; set_enemy_type
&3013 18       CLC
&3014 69 01    ADC #&01
&3016 9d 8a 01 STA &018a,X ; enemies_type
; skip_materialisation
&3019 a6 86    LDX &86 ; enemy_to_consider
&301b de 90 01 DEC &0190,X ; enemies_homing_cooldown
&301e d0 7f    BNE &309f ; skip_homing_towards_player
&3020 bd 8d 01 LDA &018d,X ; enemies_maximum_homing_cooldown
&3023 9d 90 01 STA &0190,X ; enemies_homing_cooldown
&3026 bd 8e 01 LDA &018e,X ; enemies_behaviour
&3029 f0 74    BEQ &309f ; skip_homing_towards_player               # BEHAVIOUR_0 bounces off walls
&302b c9 03    CMP #&03
&302d 90 4a    BCC &3079 ; set_random_direction                     # BEHAVIOUR_1 and BEHAVIOUR_2 move randomly
&302f d0 5f    BNE &3090 ; move_droid
; move_enemy_towards_player                                         # BEHAVIOUR_3 moves towards player
&3031 a0 00    LDY #&00
&3033 a5 70    LDA &70 ; player_screen_address_low
&3035 29 f8    AND #&f8
&3037 dd 88 01 CMP &0188,X ; enemies_screen_address_low
&303a 90 13    BCC &304f ; enemy_right_of_player
&303c f0 02    BEQ &3040 ; enemy_horizontally_aligned_with_player
&303e b0 09    BCS &3049 ; enemy_left_of_player
; enemy_horizontally_aligned_with_player
&3040 20 76 2e JSR &2e76 ; rnd_for_enemy
&3043 a0 00    LDY #&00
&3045 29 01    AND #&01
&3047 f0 06    BEQ &304f ; enemy_right_of_player
; enemy_left_of_player
&3049 98       TYA
&304a 09 01    ORA #&01 ; ENEMY_RIGHT
&304c a8       TAY
&304d d0 04    BNE &3053 ; consider_vertical_position
; enemy_right_of_player
&304f 98       TYA
&3050 09 04    ORA #&04 : ENEMY_LEFT
&3052 a8       TAY
; consider_vertical_position
&3053 a5 71    LDA &71 ; player_screen_address_high
&3055 dd 89 01 CMP &0189,X ; enemies_screen_address_high
&3058 90 15    BCC &306f ; enemy_below_player
&305a f0 02    BEQ &305e ; enemy_vertically_aligned_with_player
&305c b0 0b    BCS &3069 ; enemy_above_player
; enemy_vertically_aligned_with_player
&305e 84 8f    STY &8f ; tmp
&3060 20 76 2e JSR &2e76 ; rnd_for_enemy
&3063 a4 8f    LDY &8f ; tmp
&3065 29 01    AND #&01
&3067 f0 06    BEQ &306f ; enemy_below_player
; enemy_above_player
&3069 98       TYA
&306a 09 02    ORA #&02 ; ENEMY_DOWN
&306c a8       TAY
&306d d0 04    BNE &3073 ; set_direction                            # Always branches
; enemy_below_player
&306f 98       TYA
&3070 09 08    ORA #&08 ; ENEMY_UP
&3072 a8       TAY
; set_direction
&3073 98       TYA
&3074 9d 8b 01 STA &018b,X ; enemies_direction
&3077 d0 26    BNE &309f ; skip_homing_towards_player               # Always branches

; set_random_direction
&3079 a8       TAY
&307a b9 8d 30 LDA &308d,Y ; direction_ranges
&307d 85 8f    STA &8f ; tmp
&307f 20 76 2e JSR &2e76 ; rnd_for_enemy
&3082 25 8f    AND &8f ; tmp
&3084 a8       TAY
&3085 b9 7c 2e LDA &2e7c,Y ; random_directions_table
&3088 9d 8b 01 STA &018b,X ; enemies_direction
&308b d0 12    BNE &309f ; skip_homing_towards_player

; direction_ranges
&308d 07 ; (droids)      : all directions
&308e 07 ; (BEHAVIOUR_1) : all directions
&308f 03 ; (BEHAVIOUR_2) : diagonals only

; move_droid
&3090 20 76 2e JSR &2e76 ; rnd_for_enemy                            # Returns a random number between &00 and &0f
&3093 4a       LSR A
&3094 c9 03    CMP #&03
&3096 f0 99    BEQ &3031 ; move_enemy_towards_player                # 1 in 8 chance of droid moving towards player
&3098 a9 00    LDA #&00
&309a 90 dd    BCC &3079 ; set_random_direction                     # 3 in 8 chance of changing to a random direction
&309c 9d 8b 01 STA &018b,X ; enemies_direction                      # 1 in 2 chance of stopping
; skip_homing_towards_player
; skip_moving_enemy
&309f a5 7b    LDA &7b ; fire_hit_something
&30a1 d0 44    BNE &30e7 ; enemy_not_hit_by_fire                    # Only one enemy can be hit at once
&30a3 bd 8a 01 LDA &018a,X ; enemies_type
&30a6 c9 04    CMP #&04 ; ENEMY_DEMATERIALISING
&30a8 b0 3d    BCS &30e7 ; enemy_not_hit_by_fire                    # Dematerialising enemies can't be hit
&30aa a5 7c    LDA &7c ; fire_screen_address_low
&30ac 29 f8    AND #&f8
&30ae e9 0f    SBC #&0f
&30b0 b0 02    BCS &30b4 ; skip_floor
&30b2 a9 00    LDA #&00
; skip_floor
&30b4 dd 88 01 CMP &0188,X ; enemies_screen_address_low
&30b7 b0 2e    BCS &30e7 ; enemy_not_hit_by_fire
&30b9 a5 7c    LDA &7c ; fire_screen_address_low
&30bb 29 f8    AND #&f8
&30bd 69 08    ADC #&08
&30bf 90 02    BCC &30c3 ; skip_ceiling
&30c1 a9 ff    LDA #&ff
; skip_ceiling
&30c3 dd 88 01 CMP &0188,X ; enemies_screen_address_low
&30c6 90 1f    BCC &30e7 ; enemy_not_hit_by_fire
&30c8 bd 89 01 LDA &0189,X ; enemies_screen_address_high
&30cb 69 01    ADC #&01
&30cd c5 7d    CMP &7d ; fire_screen_address_high
&30cf 90 16    BCC &30e7 ; enemy_not_hit_by_fire
&30d1 a4 76    LDY &76 ; player_on_hopper
&30d3 c0 01    CPY #&01                                             # Fire from hopper is twice as high
&30d5 e9 03    SBC #&03
&30d7 c5 7d    CMP &7d ; fire_screen_address_high
&30d9 b0 0c    BCS &30e7 ; enemy_not_hit_by_fire
&30db a9 04    LDA #&04 ; ENEMY_DEMATERIALISING
&30dd 85 7b    STA &7b ; fire_hit_something
&30df 9d 8a 01 STA &018a,X ; enemies_type                           # Set enemey dematerialising
&30e2 a9 14    LDA #&14
&30e4 9d 93 01 STA &0193,X ; enemies_materialising
; enemy_not_hit_by_fire
&30e7 bd 93 01 LDA &0193,X ; enemies_materialising
&30ea f0 32    BEQ &311e ; enemy_not_dematerialising
&30ec c9 13    CMP #&13
&30ee d0 09    BNE &30f9 ; skip_score
&30f0 a2 50    LDX #&50                                             # Score 150 for destroying an enemy 
&30f2 a0 01    LDY #&01
&30f4 20 4f 35 JSR &354f ; increase_score
&30f7 a6 86    LDX &86 ; enemy_to_consider
; skip_score
&30f9 de 93 01 DEC &0193,X ; enemies_materialising
&30fc d0 20    BNE &311e ; enemy_not_dematerialising
&30fe 20 af 31 JSR &31af ; unplot_enemy                             # Remove enemy
&3101 a5 2e    LDA &2e ; new_enemies_cooldown
&3103 30 09    BMI &310e ; skip_new_enemy
&3105 e6 2f    INC &2f ; new_enemies_needed                         # Spawn a new enemy
&3107 20 76 2e JSR &2e76 ; rnd_for_enemy
&310a 09 20    ORA #&20
&310c 85 2e    STA &2e ; new_enemies_cooldown                       # after a random delay
; skip_new_enemy
&310e a6 86    LDX &86 ; enemy_to_consider
&3110 a0 0c    LDY #&0c
&3112 a9 00    LDA #&00
; wipe_enemy_loop
&3114 9d 88 01 STA &0188,X ; enemies_screen_address_low
&3117 e8       INX
&3118 88       DEY
&3119 d0 f9    BNE &3114 ; wipe_enemy_loop
&311b 4c a0 31 JMP &31a0 ; consider_next_enemy
; enemy_not_dematerialising
&311e bd 8a 01 LDA &018a,X ; enemies_type
&3121 f0 47    BEQ &316a ; enemy_not_touching_player
&3123 c9 04    CMP #&04 ; ENEMY_DEMATERIALISING
&3125 b0 43    BCS &316a ; enemy_not_touching_player                # Dematerialising enemies can't harm player
&3127 bd 88 01 LDA &0188,X ; enemies_screen_address_low
&312a 29 f8    AND #&f8
&312c 85 8e    STA &8e ; screen_address_low
&312e a5 70    LDA &70 ; player_screen_address_low
&3130 29 f8    AND #&f8
&3132 e9 0f    SBC #&0f
&3134 90 04    BCC &313a ; skip_left_check
&3136 c5 8e    CMP &8e ; screen_address_low
&3138 b0 30    BCS &316a ; enemy_not_touching_player
; skip_left_check
&313a 69 18    ADC #&18
&313c c5 8e    CMP &8e ; screen_address_low
&313e 90 2a    BCC &316a ; enemy_not_touching_player
&3140 a5 71    LDA &71 ; player_screen_address_high
&3142 e9 02    SBC #&02
&3144 dd 89 01 CMP &0189,X ; enemies_screen_address_high
&3147 b0 21    BCS &316a ; enemy_not_touching_player
&3149 69 03    ADC #&03
&314b dd 89 01 CMP &0189,X ; enemies_screen_address_high
&314e 90 1a    BCC &316a ; enemy_not_touching_player
; enemy_touching_player
&3150 a5 3a    LDA &3a ; player_energy_low
&3152 e9 2a    SBC #&2a                                             # Drain &002a energy for touching enemy
&3154 85 3a    STA &3a ; player_energy_low
&3156 b0 02    BCS &315a ; skip_underflow
&3158 c6 3b    DEC &3b ; player_energy_high
; skip_underflow
&315a bd 8a 01 LDA &018a,X ; enemies_type
&315d c9 03    CMP #&03 ; ENEMY_DROID                               # Is the enemy a droid?
&315f d0 09    BNE &316a ; enemy_not_touching_player
&3161 bd 8e 01 LDA &018e,X ; enemies_behaviour                      # If the enemy is a patrolling droid, behaviour is 0,
&3164 4a       LSR A                                                # otherwise behaviour is 4
&3165 4a       LSR A
&3166 09 02    ORA #&02 ; TOUCHING_DROID                            # or TOUCHING_NON_PATROLLING_DROID
&3168 85 20    STA &20 ; player_touching_death                      # Kill player
; enemy_not_touching_player
&316a bd 88 01 LDA &0188,X ; enemies_screen_address_low             # Has the enemy moved?
&316d c5 40    CMP &40 ; enemy_previous_screen_address_low
&316f d0 15    BNE &3186 ; replot_enemy
&3171 bd 89 01 LDA &0189,X ; enemies_screen_address_high
&3174 c5 41    CMP &41 ; enemy_previous_screen_address_high
&3176 d0 0e    BNE &3186 ; replot_enemy
&3178 bd 8a 01 LDA &018a,X ; enemies_type
&317b c5 42    CMP &42 ; enemy_previous_type
&317d d0 07    BNE &3186 ; replot_enemy
&317f bd 92 01 LDA &0192,X ; enemies_animation
&3182 c5 43    CMP &43 ; enemy_previous_animation
&3184 f0 1a    BEQ &31a0 ; skip_replotting_enemy
; replot_enemy
&3186 20 af 31 JSR &31af ; unplot_enemy                             # IF so, unplot enemy at old position
; unplot_enemy_at_current_position
&3189 a6 86    LDX &86 ; enemy_to_consider
&318b bd 88 01 LDA &0188,X ; enemies_screen_address_low
&318e 85 8e    STA &8e ; screen_address_low
&3190 bd 89 01 LDA &0189,X ; enemies_screen_address_high
&3193 85 8f    STA &8f ; screen_address_high
&3195 bd 92 01 LDA &0192,X ; enemies_animation
&3198 a8       TAY
&3199 bd 8a 01 LDA &018a,X ; enemies_type
&319c aa       TAX
&319d 20 bb 31 JSR &31bb ; plot_enemy                               # Replot enemy at new position
; skip_replotting_enemy
; consider_next_enemy
&31a0 18       CLC
&31a1 a5 86    LDA &86 ; enemy_to_consider
&31a3 69 0c    ADC #&0c
&31a5 85 86    STA &86 ; enemy_to_consider
&31a7 c9 30    CMP #&30
&31a9 b0 03    BCS &31ae ; leave
&31ab 4c be 2e JMP &2ebe ; update_enemies_loop
; leave
&31ae 60       RTS

; unplot_enemy
&31af a5 40    LDA &40 ; enemy_previous_screen_address_low
&31b1 85 8e    STA &8e ; screen_address_low
&31b3 a5 41    LDA &41 ; enemy_previous_screen_address_high
&31b5 85 8f    STA &8f ; screen_address_high
&31b7 a6 42    LDX &42 ; enemy_previous_type
&31b9 a4 43    LDY &43 ; enemy_previous_animation
; plot_enemy
&31bb 8a       TXA
&31bc 0a       ASL A
&31bd 0a       ASL A
&31be 85 8c    STA &8c ; sprite_address_low
&31c0 98       TYA
&31c1 05 8c    ORA &8c ; sprite_address_low
&31c3 0a       ASL A
&31c4 85 8c    STA &8c ; sprite_address_low
&31c6 0a       ASL A
&31c7 65 8c    ADC &8c ; sprite_address_low
&31c9 85 8c    STA &8c ; sprite_address_low
&31cb a9 00    LDA #&00
&31cd 85 8d    STA &8d ; sprite_address_high
&31cf 06 8c    ASL &8c ; sprite_address_low
&31d1 26 8d    ROL &8d ; sprite_address_high
&31d3 06 8c    ASL &8c ; sprite_address_low
&31d5 26 8d    ROL &8d ; sprite_address_high
&31d7 06 8c    ASL &8c ; sprite_address_low
&31d9 26 8d    ROL &8d ; sprite_address_high
&31db a5 8c    LDA &8c ; sprite_address_low
&31dd 69 c0    ADC #&c0
&31df 85 8c    STA &8c ; sprite_address_low
&31e1 a5 8d    LDA &8d ; sprite_address_high
&31e3 69 39    ADC #&39 ; &39c0 = enemy_sprites
&31e5 85 8d    STA &8d ; sprite_address_high
&31e7 a2 03    LDX #&03                                             # 12 pixels wide
&31e9 a0 02    LDY #&02                                             # 16 pixels high
&31eb 4c 26 65 JMP &6526 ; plot_unaligned_sprite

; game_over_screen
&31ee 08       PHP
&31ef 20 24 35 JSR &3524 ; flush_buffers
&31f2 20 63 35 JSR &3563 ; set_core_element_colours
&31f5 a5 25    LDA &25 ; game_time_high                             # Poke time into game over text
&31f7 20 13 35 JSR &3513 ; convert_number_to_two_digits_in_x_and_y
&31fa 8c f0 33 STY &33f0 ; game_over_text + &65
&31fd 8e f1 33 STX &33f1 ; game_over_text + &66
&3200 a5 24    LDA &24 ; game_time_low
&3202 20 13 35 JSR &3513 ; convert_number_to_two_digits_in_x_and_y
&3205 8c f3 33 STY &33f3 ; game_over_text + &68
&3208 8e f4 33 STX &33f4 ; game_over_text + &69
&320b a0 07    LDY #&07
; copy_game_over_palette_loop
&320d b9 0b 35 LDA &350b,Y ; game_over_palette                      # Hide status section
&3210 99 90 00 STA &0090,Y ; palette
&3213 88       DEY
&3214 10 f7    BPL &320d ; copy_game_over_palette_loop
&3216 20 78 34 JSR &3478 ; clear_screen
&3219 20 00 7f JSR &7f00 ; to_set_screen_colours
&321c a9 07    LDA #&07                                             # R7: Vertical sync position
&321e 8d 00 fe STA &fe00 ; video register number
&3221 a9 24    LDA #&24                                             # Balance screen for hidden status section
&3223 8d 01 fe STA &fe01 ; video register value
&3226 a9 0f    LDA #&0f
&3228 8d 6a 7f STA &7f6a ; timer2_msb
&322b 28       PLP                                                  # Carry set if game completed
&322c 90 17    BCC &3245 ; game_not_completed
&322e a2 f6    LDX #&f6
&3230 a0 33    LDY #&33 ; &33f6 = ending_text
&3232 20 80 0a JSR &0a80 ; plot_text                                # Completion text
&3235 a9 00    LDA #&00
&3237 a2 79    LDX #&79 ; &7900
&3239 20 87 35 JSR &3587 ; plot_full_core_array
&323c a2 7b    LDX #&7b ; ending_tune
&323e a0 14    LDY #&14
&3240 a9 0e    LDA #&0e
&3242 20 91 34 JSR &3491 ; play_tune
; game_not_completed
&3245 a5 9f    LDA &9f ; core_elements_placed                       # Poke core elements into game over text
&3247 18       CLC
&3248 69 61    ADC #&61 ; "a"
&324a 8d ba 33 STA &33ba ; game_over_text + &2f
&324d a5 0c    LDA &0c ; adventure_score + 1                        # Poke adventure score into game over text
&324f 20 13 35 JSR &3513 ; convert_number_to_two_digits_in_x_and_y
&3252 8e df 33 STX &33df ; game_over_text + &54
&3255 8c de 33 STY &33de ; game_over_text + &55
&3258 a5 46    LDA &46 ; score                                      # Poke score into game over text
&325a 20 13 35 JSR &3513 ; convert_number_to_two_digits_in_x_and_y
&325d 8c c5 33 STY &33c5 ; game_over_text + &3a
&3260 8e c6 33 STX &33c6 ; game_over_text + &3b
&3263 a5 47    LDA &47 ; score + 1
&3265 20 13 35 JSR &3513 ; convert_number_to_two_digits_in_x_and_y
&3268 8c c7 33 STY &33c7 ; game_over_text + &3c
&326b 8e c8 33 STX &33c8 ; game_over_text + &3d
&326e a5 48    LDA &48 ; score + 2
&3270 20 13 35 JSR &3513 ; convert_number_to_two_digits_in_x_and_y
&3273 8c c9 33 STY &33c9 ; game_over_text + &3e
&3276 20 78 34 JSR &3478 ; clear_screen
&3279 a2 8b    LDX #&8b
&327b a0 33    LDY #&33 ; &338b = game_over_text
&327d 20 80 0a JSR &0a80 ; plot_text                                # Game over text
&3280 a9 40    LDA #&40
&3282 a2 79    LDX #&79 ; &7940
&3284 20 87 35 JSR &3587 ; plot_full_core_array
&3287 a2 50    LDX #&50 ; game_over_tune
&3289 a0 14    LDY #&14
&328b a9 07    LDA #&07
&328d 20 91 34 JSR &3491 ; play_tune
; title_screen
&3290 20 78 34 JSR &3478 ; clear_screen
&3293 a2 03    LDX #&03
&3295 a0 33    LDY #&33; &3303 = title_screen_text
&3297 20 80 0a JSR &0a80 ; plot_text
&329a a2 00    LDX #&00 ; title_tune
&329c a0 14    LDY #&14
&329e a9 0a    LDA #&0a
&32a0 20 91 34 JSR &3491 ; play_tune                                # Returns character pressed if tune ended
&32a3 d0 0a    BNE &32af ; process_keypress
; title_screen_loop
&32a5 a2 53    LDX #&53
&32a7 a0 33    LDY #&33 ; &3353 = input_methods_text
&32a9 20 80 0a JSR &0a80 ; plot_text
&32ac 20 e0 ff JSR &ffe0 ; OSRDCH                                   # Wait for character
; process_keypress
&32af 38       SEC
&32b0 e9 30    SBC #&30 ; "0"
&32b2 f0 2e    BEQ &32e2 ; zero_pressed
&32b4 c9 04    CMP #&04
&32b6 b0 ed    BCS &32a5 ; title_screen_loop
&32b8 e9 00    SBC #&00
&32ba 85 8f    STA &8f ; tmp
&32bc 0a       ASL A
&32bd 0a       ASL A
&32be 65 8f    ADC &8f ; tmp
&32c0 c5 0a    CMP &0a ; input_method
&32c2 f0 e1    BEQ &32a5 ; title_screen_loop
&32c4 85 0a    STA &0a ; input_method
&32c6 0a       ASL A
&32c7 0a       ASL A
&32c8 a8       TAY
&32c9 a9 82    LDA #&82 ; COLOUR 2
&32cb 8d 53 33 STA &3353 ; input_methods_text
&32ce 8d 67 33 STA &3367 ; input_methods_text + &14
&32d1 8d 7b 33 STA &337b ; input_methods_text + &28
&32d4 a9 81    LDA #&81 ; COLOUR 1                                  # Highlight selected input method
&32d6 99 53 33 STA &3353,Y ; input_methods_text
&32d9 20 24 35 JSR &3524 ; flush_buffers
&32dc 20 24 0e JSR &0e24 ; play_enter_teleport_sound
&32df 4c a5 32 JMP &32a5 ; title_screen_loop
; zero_pressed
&32e2 a2 2c    LDX #&2c ; start_game_tune
&32e4 a0 14    LDY #&14
&32e6 a9 07    LDA #&07
&32e8 20 91 34 JSR &3491 ; play_tune
&32eb 20 78 34 JSR &3478 ; clear_screen
&32ee a9 07    LDA #&07                                             # R7: Vertical sync position
&32f0 8d 00 fe STA &fe00 ; video register number
&32f3 a9 1e    LDA #&1e                                             # Balance screen for visible status section
&32f5 8d 01 fe STA &fe01 ; video register value
&32f8 a9 1b    LDA #&1b
&32fa 8d 6a 7f STA &7f6a ; timer2_msb
&32fd 20 1c 11 JSR &111c ; start_game
&3300 4c ee 31 JMP &31ee ; game_over_screen

; title_screen_text
&3303 83                                              ; COLOUR 3
&3304 1f 0a 0a                                        ; TAB(&0a, &0a)
&3307 53 5d 54 5d 41 5d 52 5d 51 5d 55 5d 41 5d 4b 5d ; "S-T-A-R-Q-U-A-K-E"
&3317 45
&3318 1f 0f 14                                        ; TAB(&0f, &14)
&331b 42 59 00 00 4b 45 4e 54 4f 4e 00 00 50 52 49 43 ; "BY  KENTON  PRICE"
&332b 45
&332c 1f 0b 15                                        ; TAB(&0b, &14)
&332f 43 5e 62 6a 69 68 00 00 42 55 42 42 4c 45 00 00 ; "C.1987  BUBBLE  BUS"
&33ff 42 55 53
&3342 82                                              ; COLOUR 2
&3343 1f 0e 11                                        ; TAB(&0e, &11)
&3346 61 5e 00 53 54 41 52 54 5b 47 41 4d 45          ; "0. START GAME"
; input_methods_text
&3353 81                                              ; COLOUR 1
&3354 1f 0e 0d                                        ; TAB(&0e, &0d)
&3357 62 5e 00 4b 45 59 42 4f 41 52 44 5b 5a 58 6b 6c ; "1. KEYBOARD ZX=/"
&3367 82                                              ; COLOUR 2
&3368 1f 0e 0e                                        ; TAB(&0e, &0e)
&336b 63 5e 00 4b 45 59 42 4f 41 52 44 5b 55 5e 44 5e ; "2. KEYBOARD U.D."
&337b 82                                              ; COLOUR 2
&337c 1f 0e 0f                                        ; TAB(&0e, &0f)
&337f 64 5e 00 4a 4f 59 53 54 49 43 4b                ; "3. JOYSTICK"
&338a 0d


; game_over_text
&338b 1f 18 07
&338e 83
&338f 47 41 4d 45 5b 4f 56 45 52                      ; "GAME OVER"
&3398 1f 12 12
&339b 82
&339c 43 4f 52 45                                     ; "CORE"
&33a0 1f 0a 13
&33a3 45 4c 45 4d 45 4e 54 53                         ; "ELEMENTS"
&33ab 1f 0a 14
&33ae 52 45 50 4c 41 43 45 44                         ; "PLACED"
&33b6 1f 16 16
&33b9 61 61                                           ; "00"
&33bb 81
&33bc 1f 14 0a
&33bf 53 43 4f 52 45 5b 61 61 61 61 61                ; "SCORE 00000"
&33cc 1f 04 0c
&33cd 41 44 56 45 4e 54 55 52 45 00 00 53 43 4f 52 45 ; "ADVENTURE  SCORE 00"
&33dd 5b 61 61 60
&33e1 1f 0b 0e
&33e4 54 49 4d 45 00 00 54 41 4b 45 4e 5b 61 61 6b 61 ; "TIME  TAKEN 00:00"
&33f4 61
&33f5 0d

; ending_text
&33f6 82
&33f7 1f 08 06
&33fa 54 48 45 5b 43 4f 52 45 53 5b 43 4f 4d 50 4c 45 ; "THE CORES COMPLETE"
&340a 54 45
&340c 1f 02 08
&340f 42 55 54 5b 48 4f 57 5b 41 52 45 5b 59 4f 55 5b ; "BUT HOW ARE YOU GONNA"
&341f 47 4f 4e 4e 41
&3424 1f 04 0a
&3427 47 45 54 5b 48 4f 4d 45 5b 57 48 45 4e 5b 4f 4e ; "GET HOME WHEN ONLY A"
&3437 4c 59 5b 41
&343b 1f 06 0c
&343e 54 48 54 55 50 49 44 5b 4c 4f 4f 4e 59 5b 57 4f ; "THTUPID LOONY WOULD"
&344e 55 4c 44
&3451 1f 06 0e
&3454 57 41 4e 44 45 52 5b 54 48 49 53 5b 46 41 52 5b ; "WANDER THIS FAR OUT"
&3464 4f 55 54
&3467 1f 12 10
&346a 49 4e 5b 54 48 45 5b 47 41 4c 41 58 59          ; "IN THE GALAXY"
&3477 0d

; clear_screen
&3478 a9 00    LDA #&00
&347a 85 8e    STA &8e ; screen_address_low
&347c a9 6d    LDA #&6d ; &6d00
&347e 85 8f    STA &8f ; screen_address_high
; clear_screen_page_loop
&3480 a9 00    LDA #&00
&3482 a8       TAY
; clear_screen_loop
&3483 91 8e    STA (&8e),Y ; screen_address                         # Wipe &6d00 - &7fff
&3485 c8       INY
&3486 d0 fb    BNE &3483 ; clear_screen_loop
&3488 e6 8f    INC &8f ; screen_address_high
&348a a5 8f    LDA &8f ; screen_address_high
&348c c9 7f    CMP #&7f
&348e d0 f0    BNE &3480 ; clear_screen_page_loop
&3490 60       RTS

; play_tune
&3491 86 8c    STX &8c ; tune_offset
&3493 85 8d    STA &8d ; speed
&3495 84 8f    STY &8f ; pitch_change
&3497 a2 6f    LDX #&6f
&3499 a0 04    LDY #&04 ; &046f = tune_envelope
&349b a9 08    LDA #&08 ; Define a sound envelope (ENVELOPE)
&349d 20 f1 ff JSR &fff1 ; OSWORD
; play_tune_loop
&34a0 a6 8c    LDX &8c ; tune_offset
&34a2 bd 7d 04 LDA &047d,X ; tune_data
&34a5 c9 ff    CMP #&ff                                             # &ff marks end of tune
&34a7 f0 53    BEQ &34fc ; leave_after_flushing_buffers
&34a9 48       PHA
&34aa 29 1f    AND #&1f
&34ac 0a       ASL A
&34ad 0a       ASL A
&34ae 65 8f    ADC &8f ; pitch_change
&34b0 8d 07 35 STA &3507 ; tune_sound + 4                           # Set pitch
&34b3 68       PLA
&34b4 29 e0    AND #&e0
&34b6 0a       ASL A
&34b7 2a       ROL A
&34b8 2a       ROL A
&34b9 2a       ROL A
&34ba 69 01    ADC #&01
&34bc 85 8b    STA &8b ; note_length
&34be a6 8d    LDX &8d ; speed
&34c0 a9 00    LDA #&00
; lengthen_note_loop
&34c2 65 8b    ADC &8b ; note_length
&34c4 ca       DEX
&34c5 d0 fb    BNE &34c2 ; lengthen_note_loop
&34c7 85 8b    STA &8b ; note_length
&34c9 a9 11    LDA #&11
&34cb 8d 03 35 STA &3503 ; tune_sound                               # Set channel
; play_note_loop
&34ce a2 03    LDX #&03
&34d0 a0 35    LDY #&35 ; &3503 = tune_sound
&34d2 a9 07    LDA #&07 ; Generate a sound (SOUND)
&34d4 20 f1 ff JSR &fff1 ; OSWORD
&34d7 ee 03 35 INC &3503 ; tune_sound                               # Next channel
&34da ee 07 35 INC &3507 ; tune_sound + 4
&34dd ad 03 35 LDA &3503 ; tune_sound
&34e0 c9 14    CMP #&14                                             # Play note on channels 1 - 3
&34e2 d0 ea    BNE &34ce ; play_note_loop
; wait_for_next_note
&34e4 a9 81    LDA #&81 ; Wait for input character
&34e6 a2 00    LDX #&00
&34e8 a0 00    LDY #&00
&34ea 20 f4 ff JSR &fff4 ; OSBYTE                                   # Returns X = character
&34ed 90 0d    BCC &34fc ; leave_after_flushing_buffers             # Leave if a key is pressed
&34ef a9 13    LDA #&13 ; Wait for v-sync
&34f1 20 f4 ff JSR &fff4 ; OSBYTE
&34f4 c6 8b    DEC &8b ; note_length
&34f6 d0 ec    BNE &34e4 ; wait_for_next_note
&34f8 e6 8c    INC &8c ; tune_offset
&34fa d0 a4    BNE &34a0 ; play_tune_loop
; leave_after_flushing_buffers
&34fc 8a       TXA
&34fd 48       PHA
&34fe 20 24 35 JSR &3524 ; flush_buffers
&3501 68       PLA
&3502 60       RTS                                                  # Leave with character pressed, or zero if tune ended

; tune_sound
;     chan  vol   pitch dur
&3503 11 00 04 00 00 00 19 00

; game_over_palette                                                 # Use red, green and white for game over screen,
&350b 00 00 00 01 00 02 00 07                                       # hide status section

; convert_number_to_two_digits_in_x_and_y
&3513 48       PHA
&3514 29 0f    AND #&0f
&3516 18       CLC
&3517 69 61    ADC #&61 ; "a"
&3519 aa       TAX
&351a 68       PLA
&351b 4a       LSR A
&351c 4a       LSR A
&351d 4a       LSR A
&351e 4a       LSR A
&351f 18       CLC
&3520 69 61    ADC #&61 ; "a"
&3522 a8       TAY
&3523 60       RTS

; flush_buffers
&3524 a9 0f    LDA #&0f ; Flush all buffers
&3526 a2 00    LDX #&00
&3528 4c f4 ff JMP &fff4 ; OSBYTE

; play_sound_using_envelope
&352b 18       CLC
&352c 8a       TXA
&352d 69 0e    ADC #&0e
&352f 48       PHA
&3530 98       TYA
&3531 69 00    ADC #&00
&3533 48       PHA
&3534 a9 08    LDA #&08 ; Define a sound envelope (ENVELOPE)
&3536 20 f1 ff JSR &fff1 ; OSWORD
&3539 68       PLA
&353a a8       TAY
&353b 68       PLA
&353c aa       TAX
; play_sound
&353d a9 07    LDA #&07 ; Generate a sound (SOUND)
&353f 4c f1 ff JMP &fff1 ; OSWORD

; wait_for_a_frames
&3542 48       PHA
&3543 a9 13    LDA #&13 ; Wait for v-sync
&3545 20 f4 ff JSR &fff4 ; OSBYTE
&3548 68       PLA
&3549 38       SEC
&354a e9 01    SBC #&01
&354c d0 f4    BNE &3542 ; wait_for_a_frames
&354e 60       RTS

; increase_score
&354f 18       CLC
&3550 f8       SED
&3551 8a       TXA
&3552 65 48    ADC &48 ; score + 2
&3554 85 48    STA &48 ; score + 2
&3556 98       TYA
&3557 65 47    ADC &47 ; score + 1
&3559 85 47    STA &47 ; score + 1
&355b a5 46    LDA &46 ; score
&355d 69 00    ADC #&00
&355f 85 46    STA &46 ; score
&3561 d8       CLD
&3562 60       RTS

; set_core_element_colours
&3563 a0 08    LDY #&08
; set_core_element_colours_loop
&3565 a9 ff    LDA #&ff
&3567 b6 17    LDX &17,Y ; core_elements_required
&3569 30 03    BMI &356e ; set_colour
&356b b9 75 35 LDA &3575,Y ; initial_core_element_colours
; set_colour
&356e 99 f7 0b STA &0bf7,Y ; core_elements_colours
&3571 88       DEY
&3572 10 f1    BPL &3565 ; set_core_element_colours_loop
&3574 60       RTS

; initial_core_element_colours
;      2  1  2  1  2  1  2  1  2
&3575 f0 0f f0 0f f0 0f f0 0f f0

; core_elements_plotted
&357e 00 00 00 00 00 00 00 00 00

; plot_full_core_array
&3587 48       PHA
&3588 a0 08    LDY #&08
; mark_elements_as_unplotted_loop
&358a a9 01    LDA #&01                                             # Not a colour to indicate core element needs plotting
&358c 99 7e 35 STA &357e,Y ; core_elements_plotted
&358f 88       DEY
&3590 10 f8    BPL &358a ; mark_elements_as_unplotted_loop
&3592 68       PLA
; plot_partial_core_array
&3593 85 69    STA &69 ; row_screen_address_low
&3595 86 89    STX &89 ; row_screen_address_high
&3597 a9 00    LDA #&00
&3599 85 87    STA &87 ; core_element_to_plot
; plot_core_elements_column_loop
&359b a9 68    LDA #&68
&359d 85 88    STA &88 ; element_screen_address_low
; plot_core_elements_row_loop
&359f 18       CLC
&35a0 a5 88    LDA &88 ; element_screen_address_low
&35a2 65 69    ADC &69 ; row_screen_address_low
&35a4 85 8e    STA &8e ; screen_address_low
&35a6 a5 89    LDA &89 ; row_screen_address_high
&35a8 85 8f    STA &8f ; screen_address_high
&35aa a4 87    LDY &87 ; core_element_to_plot
&35ac b9 f7 0b LDA &0bf7,Y ; core_elements_colours
&35af d9 7e 35 CMP &357e,Y ; core_elements_plotted
&35b2 f0 09    BEQ &35bd ; skip_element
&35b4 aa       TAX
&35b5 b9 17 00 LDA &0017,Y ; core_elements_required
&35b8 a0 00    LDY #&00                                             # Overwrite screen
&35ba 20 b3 0b JSR &0bb3 ; plot_packed_two_colour_sprite
; skip_element
&35bd e6 87    INC &87 ; core_element_to_plot
&35bf 18       CLC
&35c0 a5 88    LDA &88 ; element_screen_address_low
&35c2 69 10    ADC #&10
&35c4 85 88    STA &88 ; element_screen_address_low
&35c6 c9 98    CMP #&98
&35c8 90 d5    BCC &359f ; plot_core_elements_row_loop
&35ca e6 89    INC &89 ; row_screen_address_high
&35cc e6 89    INC &89 ; row_screen_address_high
&35ce a5 87    LDA &87 ; core_element_to_plot
&35d0 c9 09    CMP #&09
&35d2 90 c7    BCC &359b ; plot_core_elements_loop
&35d4 a0 08    LDY #&08
; mark_elements_as_plotted_loop
&35d6 b9 f7 0b LDA &0bf7,Y ; core_elements_colours
&35d9 99 7e 35 STA &357e,Y ; core_elements_plotted
&35dc 88       DEY
&35dd 10 f7    BPL &35d6 ; mark_elements_as_plotted_loop
&35df 60       RTS

; packed_two_colour_sprite_data
; packed_sprite_00 ITEM_ENERGY
&35e0 53 b5 bb ba ec f6 f7 fb 50 05 8b 0f a0 0a 1f 0f
; packed_sprite_01 ITEM_ENGERY_2
&35f0 73 57 75 13 ec ae ea 8c 62 d6 85 0d 64 b6 1a 0b
; packed_sprite_02 ITEM_ENERGY_3
&3600 56 08 21 22 73 0d c8 cc 62 56 d5 0f ec a6 fa 0f
; packed_sprite_03 ITEM_AMMO
&3610 12 04 26 01 a8 41 09 04 22 22 52 0b cc cc a4 0f
; packed_sprite_04 ITEM_FUEL
&3620 c0 1d 64 90 30 8b 62 90 f4 dd 0f 0b f2 33 0f 0d
; packed_sprite_05 ITEM_LIFE
&3630 21 32 01 11 c8 cc 08 88 11 70 fc 07 88 e0 f3 0e
; packed_sprite_06 ITEM_RANDOM
&3640 ac 31 74 43 53 c8 e2 2c 37 74 43 03 ce e2 2c 0c
; packed_sprite_07 PYRAMID
&3650 11 22 44 88 88 cc ee ff 0f 57 45 07 0f 2e 2a 0e
; packed_sprite_08 ITEM_EMPTY
&3660 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
; packed_sprite_09 ITEM_PASS
&3670 00 00 c7 ef 00 00 3e 7f ce 8c 99 07 77 bb 11 0e
; packed_sprite_0a ITEM_KEY
&3680 00 40 66 55 00 00 00 00 54 65 46 00 7f 15 00 00
; packed_sprite_0b ITEM_CORE_TOP_LEFT
&3690 00 00 00 00 31 13 20 44 00 11 42 ee 88 00 00 31
; packed_sprite_0c ITEM_CORE_TOP
&36a0 90 3b 81 2a 90 cd 18 45 44 84 1a 93 22 12 85 9c
; packed_sprite_0d ITEM_CORE_TOP_RIGHT
&36b0 c8 8c 40 22 00 00 00 00 11 00 00 c8 00 88 24 77
; packed_sprite_0e ITEM_CORE_LEFT
&36c0 24 01 10 e4 13 42 28 30 4e 20 10 40 03 42 08 35
; packed_sprite_0f ITEM_CORE_MIDDLE
&36d0 08 10 33 77 01 80 cc ee 55 32 01 80 ee cc 08 10
; packed_sprite_10 ITEM_CORE_RIGHT
&36e0 8c 24 41 c0 42 08 80 72 0c 24 01 ca 27 40 80 20
; packed_sprite_11 ITEM_CORE_BOTTOM_LEFT
&36f0 ee 24 11 00 13 00 00 88 00 00 00 00 44 02 31 13
; packed_sprite_12 ITEM_CORE_BOTTOM
&3700 39 a1 48 44 c9 58 21 22 a2 18 b3 09 54 81 dc 09
; packed_sprite_13 ITEM_CORE_BOTTOM_RGHT
&3710 8c 00 00 11 77 42 88 00 22 04 c8 8c 00 00 00 00
; packed_sprite_14 ITEM_CORE_CHIP_1
&3720 00 30 77 77 00 e0 77 33 77 03 55 05 f3 0e 55 05
; packed_sprite_15 ITEM_CORE_CHIP_2
&3730 00 30 76 66 00 e0 b3 73 76 03 55 05 f3 0e 55 05
; packed_sprite_16 ITEM_CORE_CHIP_3
&3740 00 30 76 77 00 e0 b3 73 77 03 55 05 7f 0e 55 05
; packed_sprite_17 ITEM_CORE_TRANSISTOR
&3750 10 23 22 07 c0 e6 ee 0f 22 22 44 04 aa aa 59 05
; packed_sprite_18 ITEM_CORE_XXX
&3760 00 31 65 56 00 ec b5 5b 35 10 22 62 e5 40 22 32
; packed_sprite_19 ITEM_CORE_AERIAL
&3770 00 20 27 00 22 aa af aa 00 00 10 01 02 e4 fe 0f
; packed_sprite_1a ITEM_CORE_LIGHTBULB
&3780 21 55 55 22 ec ff ff ee 11 10 10 00 c4 c0 c8 08
; packed_sprite_1b ITEM_CORE_FLOPPY
&3790 70 44 77 67 f0 67 ff b7 76 77 77 07 7b 7f 77 0f
; packed_sprite_1c ITEM_CORE_BOTTLE
&37a0 00 01 01 21 80 cc 0c 2c 23 22 03 03 ee ee 0e 0e
; packed_sprite_1d ITEM_CORE_EXTINGUISHER
&37b0 40 77 14 11 f0 66 0f 88 31 33 33 03 c8 40 04 0c 

; possible_item_locations                                           # One byte per room, low six bits set tile
&37c0 19 a5 12 5a 5e e3 e4 dc 23 e2 53 1e e3 1e 4c 0b
&37d0 66 a3 59 52 62 54 c9 1e 64 e4 0e 62 64 19 56 60
&37e0 23 9a 1e 09 13 e2 1e c9 13 19 e4 e2 e4 14 e1 16
&38f0 a5 20 1e 19 e4 a1 13 15 9d e2 15 21 0e 09 26 4a
&3800 21 e1 16 12 54 27 24 0d 3f 12 e2 e3 20 e2 21 1d
&3810 0e 1d 65 0a 21 0d 1b 26 51 e4 e2 12 0b 13 1e 16
&3820 27 05 1d 20 14 11 12 91 92 11 3f 4c 24 e2 e3 20
&3830 16 27 4c 05 1d a1 e4 1d 21 4a e2 1d d9 e3 0b 0a
&3840 14 e1 e1 14 e3 e1 15 54 e1 0e 20 95 20 e0 4b 12
&3850 12 1d 0d e1 20 56 22 12 27 1d 64 14 09 14 65 12
&3860 12 a5 12 11 e2 1a 64 21 0b 64 e2 e3 e0 11 da 65
&3870 27 16 09 10 16 25 60 21 e3 20 27 dc 16 51 9d 0d
&3880 1b 16 9d e4 1e 93 25 3f 11 16 15 66 66 5b 14 26
&3890 02 13 5a 0d 51 5e 23 25 0c e1 11 21 66 60 04 16
&38a0 02 e2 16 e2 1b 16 1b 20 12 1d 0c 93 e1 62 e1 01
&38b0 53 64 a3 5b e2 e3 60 1d e1 19 21 e4 9d 19 58 06
&38c0 51 16 66 23 62 1b 1d 58 59 5e 5e 58 58 27 4c 11
&38d0 11 1e e1 d0 27 e2 1f 21 1b 13 98 14 e2 e1 20 26
&38e0 54 e0 a2 27 e2 27 54 15 1b 14 1d 1b 14 27 0a 1b
&38f0 27 0a 1d 61 e2 e1 3f 05 51 0c 1c 27 1a 20 20 0d
&3900 e3 1d 14 e2 63 66 60 16 e2 ca 1a e2 60 e2 9c 16
&3910 1b e0 27 e2 e0 1d 15 9a 1d e4 04 27 15 27 20 42
&3920 1c 16 16 0b 12 0c 1b 16 11 21 21 12 e2 e1 e4 e2
&3930 27 41 53 26 06 19 a4 1e 16 1d 0a 27 9c 16 1b 19
&3940 0b a4 43 e3 e1 14 27 e2 63 1a 19 e1 27 e3 0b 06
&3950 e2 16 12 20 20 19 5c 27 20 12 11 16 11 e1 1d 01
&3960 27 1a 27 27 16 4b 09 27 27 20 43 19 66 5e e3 3f
&3970 12 19 59 4b 06 16 16 20 53 0c 05 15 15 1d 12 1d
&3980 09 1a e3 27 27 e1 e2 e1 e0 16 1d 0a e2 12 0d 24
&3990 61 65 21 1a 27 1a a0 1a 15 1d 12 1a 20 3f 62 20
&39a0 27 66 14 ca e1 0d 66 27 e1 27 20 3f 12 21 3f 26
&39b0 21 3f 27 a5 60 43 3f a4 21 26 26 e3 66 3f ca e1 

; enemy_sprites
; enemy_materialising_frame_1
&39c0 00 41 00 08 00 00 00 cc 80 00 60 00 34 40 33 33
&39d0 00 00 00 00 00 00 00 00 cc cc 20 c2 00 60 00 10
&39e0 33 00 00 00 01 00 28 00 00 00 00 00 00 00 00 00
; enemy_materialising_frame_2
&39f0 00 00 00 66 66 66 00 00 80 02 00 30 00 10 02 10
&3a00 00 00 00 00 00 08 00 80 60 01 24 00 30 00 01 00
&3a10 00 00 11 11 11 00 00 40 00 00 88 88 88 00 00 00
; enemy_materialising_frame_3
&3a20 00 00 20 20 10 02 30 00 cc cc cd 00 08 00 00 00
&3a30 00 00 00 00 80 00 08 40 20 01 00 10 00 00 00 00
&3a40 00 00 00 01 00 3b 33 33 00 c0 04 80 40 40 00 00
; enemy_materialising_frame_4
&3a50 00 00 00 10 00 00 00 01 14 a0 a0 20 00 80 00 00
&3a60 00 00 cc cc cc 00 00 00 00 00 00 00 00 00 00 00
&3a70 00 00 00 cc dc dc 10 20 02 00 40 00 20 40 40 08
; enemy_type_one_frame_1
&3a80 08 0c 06 02 01 01 20 60 01 03 06 04 08 08 40 60
&3a90 00 00 00 00 00 00 00 00 70 d0 22 54 66 90 f0 50
&3aa0 e0 b0 54 a2 66 90 f0 a0 00 00 00 00 00 00 00 00
; enemy_type_one_frame_2
&3ab0 00 00 06 07 00 00 10 30 00 00 01 03 0c 0c 20 30
&3ac0 00 00 08 08 00 00 00 00 30 60 51 22 33 60 70 10
&3ad0 f0 d0 22 d1 33 d0 f0 60 00 80 80 00 00 80 80 00
; enemy_type_one_frame_3
&3ae0 00 00 00 01 03 02 00 10 00 00 00 09 06 06 90 90
&3af0 00 00 00 08 0c 04 00 80 10 30 20 11 11 20 30 10
&3b00 f0 60 99 60 99 60 f0 80 80 c0 40 88 88 40 c0 80
; enemy_type_one_frame_4
&3b10 00 00 01 01 00 00 00 00 00 00 08 0c 03 03 40 c0
&3b20 00 00 06 0e 00 00 80 c0 00 10 10 00 00 10 10 00
&3b30 f0 b0 44 b8 cc 30 f0 60 c0 60 a8 44 cc 20 e0 80
; enemy_type_two_frame_1
&3b40 02 15 15 15 0a 0f 0e 04 aa 55 55 f5 a0 00 00 01
&3b50 00 00 00 00 00 00 00 00 0c 0c 06 0e 0b 07 05 03
&3b60 01 02 03 07 0f 0e 0a 0c 00 00 00 00 00 00 00 00
; enemy_type_two_frame_2
&3b70 01 02 02 02 05 07 07 02 55 aa aa fa 50 08 00 00
&3b80 00 88 88 88 00 00 00 08 06 06 03 07 05 03 02 01
&3b90 00 01 01 03 0f 0f 0d 0e 08 00 08 08 08 00 00 00
; enemy_type_two_frame_3
&3ba0 00 01 01 01 02 03 03 01 2a 55 55 75 28 0c 08 00
&3bb0 88 44 44 c4 80 00 00 08 03 03 01 03 02 01 01 00
&3bc0 00 00 08 09 0f 0f 06 0f 08 0c 0c 08 0c 08 08 00
; enemy_type_two_frame_4
&3bd0 00 00 00 00 01 01 01 00 15 2a 2a 3a 14 0e 0c 08
&3ce0 44 aa aa ea 40 00 00 04 01 01 00 01 01 00 00 00
&3cf0 08 08 0c 0c 07 0f 0b 07 04 06 06 0c 0e 0c 04 08
; enemy_type_three_frame_1
&3c00 11 22 22 00 bb bb bb 00 88 cc cc 00 bb bb bb 00
&3c10 00 00 00 00 00 00 00 00 22 22 22 22 00 55 00 11
&3c20 cc cc cc cc 00 ee 00 88 00 00 00 00 00 00 00 00
; enemy_type_three_frame_2
&3c30 00 11 11 00 33 33 33 00 cc 66 66 00 bb bb bb 00
&3c40 00 00 00 00 88 88 88 00 11 11 11 11 00 33 00 00
&3c50 66 66 66 66 00 dd 00 cc 00 00 00 00 00 00 00 00
; enemy_type_three_frame_3
&3c60 00 00 00 00 33 33 33 00 66 bb bb 00 bb bb bb 00
&3c70 00 00 00 00 88 88 88 00 00 00 00 00 00 11 00 00
&3c80 bb bb bb bb 00 dd 00 66 00 00 00 00 00 88 00 00
; enemy_type_three_frame_4
&3c90 00 00 00 00 11 11 11 00 33 55 55 00 bb bb bb 00
&3ca0 00 88 88 00 aa aa aa 00 00 00 00 00 00 00 00 00
&3cb0 55 55 55 55 00 dd 00 33 88 88 88 88 00 cc 00 00

; player_materialising_frame_1                                      # Also dematerialising enemies and platform fire
&3cc0 22 77 22 88 00 22 88 00 00 44 11 00 22 77 22 00
&3cd0 00 00 00 00 00 00 00 00 00 44 00 00 99 00 44 00
&3ce0 88 00 22 88 cc 99 22 00 00 00 00 00 00 00 00 00
; player_materialising_frame_2
&3cf0 00 00 11 00 44 11 44 00 22 88 cc 88 11 33 11 88
&3d00 00 00 00 00 00 88 00 00 00 22 11 33 11 44 22 00
&3d10 00 22 00 88 11 00 00 88 00 00 00 88 00 00 88 00
; player_materialising_frame_3
&3d20 00 00 00 11 00 22 00 00 99 00 88 cc 99 00 00 11
&3d30 00 00 88 00 00 00 88 cc 00 11 00 00 11 00 00 22
&3d40 44 00 22 00 00 44 ee 44 88 00 00 00 00 88 00 44
; player_materialising_frame_4
&3d50 00 00 11 00 00 00 00 00 22 00 11 44 ee 44 00 44
&3d60 22 00 00 44 00 00 00 22 11 00 00 11 00 00 11 00
&3d70 11 88 00 22 00 88 dd 88 00 44 ee 44 00 00 00 44

; player_sprites
; player_left_frame_1
&3d80 11 00 33 55 22 66 88 cc bb dd 44 aa ee 77 33 77
&3d90 00 00 00 00 00 00 00 00 ee ff ff 66 66 bb 88 66
&3da0 ff ff 77 aa cc 22 66 cc 00 00 00 00 00 00 00 00
; player_left_frame_2
&3db0 00 00 11 22 11 33 44 66 dd 66 aa dd 77 33 11 33
&3dc0 88 88 00 00 00 88 88 88 77 77 77 33 33 55 44 33
&3dd0 77 ff bb 55 66 99 33 66 88 88 88 00 00 00 00 00
; player_left_frame_3
&3de0 00 00 00 11 00 11 22 33 33 11 dd 66 bb 99 00 11
&3df0 44 00 00 88 88 cc cc cc 33 33 33 11 11 00 00 00
&3e00 bb ff dd aa aa 22 ee 66 cc cc cc 88 88 00 cc 88
; player_left_frame_4
&3e10 00 00 00 00 00 00 11 11 11 00 66 bb 55 cc 00 88
&3e20 aa 88 88 44 cc ee 66 ee 11 11 11 00 00 00 00 00
&3e30 dd ff ee dd dd 11 77 33 ee ee ee 44 44 00 66 44
; player_left_frame_5
&3e40 11 00 33 55 22 66 88 cc bb 66 44 aa ee 77 33 77
&3e50 00 00 00 00 00 00 00 00 ee ff ff 66 66 11 77 22
&3e60 ff ff 77 aa aa 99 33 66 00 00 00 00 00 00 00 00
; player_left_frame_6
&3e70 00 00 11 22 11 33 44 66 dd 33 aa dd 77 33 11 33
&3e80 88 00 00 00 00 88 88 88 77 77 77 33 33 00 33 11
&3e90 77 ff bb 55 55 cc 99 33 88 88 88 00 00 88 88 00
; player_left_frame_7
&3ea0 00 00 00 11 00 11 22 33 55 11 dd 66 bb 99 00 11
&3eb0 88 00 00 88 88 cc cc cc 33 33 33 11 11 22 22 11
&3ec0 bb ff dd aa bb dd 33 66 cc cc cc 88 00 00 00 00
; player_left_frame_8
&3ed0 00 00 00 00 00 00 11 11 22 00 66 bb 55 cc 00 88
&3ee0 cc 88 88 44 cc ee 66 ee 11 11 11 00 00 11 11 00
&3ef0 dd ff ee dd dd 66 11 bb ee ee ee 44 88 88 88 00
; player_right_frame_1
&3f00 66 22 22 55 77 ee cc ee 88 00 cc aa 44 66 11 33
&3f10 00 00 00 00 00 00 00 00 ff ff ee 55 33 22 33 11
&3f20 77 ff ff 66 66 dd 11 aa 00 00 00 00 00 00 00 00
; player_right_frame_2
&3f30 33 11 11 22 33 77 66 77 44 00 66 dd aa 33 00 11
&3f40 00 00 00 00 00 00 88 88 77 77 77 22 11 11 11 00
&3f50 bb ff 77 bb bb 66 88 dd 88 88 88 00 00 88 88 00
; player_right_frame_3
&3f60 33 11 00 11 11 33 33 33 66 88 bb 66 dd 99 00 88
&3f70 00 00 00 88 00 88 44 cc 33 33 33 11 11 22 33 11
&3f80 dd ff bb 55 55 66 33 99 cc cc cc 88 88 00 88 00
; player_right_frame_4
&3f90 11 00 00 00 00 11 11 11 bb cc 55 bb ee cc 88 cc
&4fa0 00 00 88 44 88 cc 22 66 11 11 11 00 00 11 11 00
&4fb0 ee ff dd aa aa 33 99 cc ee ee ee cc cc 00 cc 88
; player_right_frame_5
&4fc0 bb 22 22 55 77 ee cc ee 00 00 cc aa 44 66 11 33
&4fd0 00 00 00 00 00 00 00 00 ff ff ee 55 55 11 dd 55
&4fe0 77 ff ff 66 66 00 cc 88 00 00 00 00 00 00 00 00
; player_right_frame_6
&4ff0 55 11 11 22 33 77 66 77 88 00 66 dd aa 33 00 11
&4000 00 00 00 00 00 00 88 88 77 77 77 22 22 00 66 22
&4010 bb ff 77 bb bb 88 ee cc 88 88 88 00 00 00 00 00
; player_right_frame_7
&4020 33 22 00 11 11 33 33 33 66 cc bb 66 dd 99 00 88
&4030 00 00 00 88 00 88 44 cc 33 33 33 11 00 11 11 00
&4040 dd ff bb 55 dd 33 88 dd cc cc cc 88 88 44 44 88
; player_right_frame_8
&4050 11 11 00 00 00 11 11 11 bb 66 55 bb ee cc 88 cc
&4060 00 00 88 44 88 cc 22 66 11 11 11 00 00 00 00 00
&4070 ee ff dd aa 66 99 cc 66 ee ee ee cc cc aa 22 cc

; bridging_platform_sprites                                         # EORed successively
; bridging_platform_frame_1
&4080 00 00 44 00 00 00 88 11 00 00 22 00 00 00 44 00
; bridging_platform_frame_2
&4090 00 00 00 11 00 00 00 00 00 00 88 00 22 00 00 00
; bridging_platform_frame_3
&40a0 00 88 00 00 44 00 22 00 00 33 00 88 00 88 00 00
; bridging_platform_frame_4
&40b0 00 44 99 00 00 11 00 00 00 00 11 00 00 00 11 88
; bridging_platform_frame_5
&40c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
; bridging_platform_frame_6
&40d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
; bridging_platform_frame_7
&40e0 00 cc dd 11 44 11 aa 11 00 33 bb 88 22 88 55 88
; bridging_platform_frame_8
&40f0 00 cc dd 11 44 11 aa 11 00 33 bb 88 22 88 55 88

; fire_sprites
; fire_frame_1
&4100 22 55 00 00 00 00 00 00 22 55 88 00 00 00 00 00
; fire_frame_2
&4110 00 55 22 00 00 00 00 00 88 55 22 00 00 00 00 00 

; hopper_sprites
; hopper_frame_1
&4120 dd 00 55 bb bb dd 55 00 dd 00 aa 55 55 bb aa 00
&4130 00 00 00 00 00 00 00 00
; hopper_frame_2
&4138 55 00 22 55 55 66 22 00 dd 00 dd 66 66 dd dd 00
&4148 88 00 00 88 88 88 00 00
; hopper_frame_3
&4150 11 00 11 22 22 33 11 00 dd 00 66 77 77 66 66 00
&4160 cc 00 88 44 44 cc 88 00
; hopper_frame_4
&4168 11 00 00 11 11 11 00 00 dd 00 bb 77 77 bb bb 00
&4178 cc 00 44 22 22 66 44 00

# Room data
# =========
# Twelve bytes per room
#
# First byte:
# .....421 room_primary_wall_type
# 84...... palette + 5
# ...18... palette + 3
#
# Second byte:
# 8421.... room_extras_types + 1
# ....8421 room_extras_types
#
# Third and fourth, fifth and sixth bytes:
# 84...... 84...... room_additional_wall_types
# ..218421 ........ extra position
# ........ ..218421 extra position
#
# Seventh through twelve bytes are bitmaps for walls, one byte per row

; room_data
;      0  1  2  3  4  5  6  7  8  9  a  b
&4180 d8 5f 13 3f 55 2f ff fa 9e 80 c0 c0 ; room &000
&418c 49 30 3f 3f 11 3f ff 32 60 08 00 c7 ; room &001
&4198 41 20 3f 3f 3f 3f ff 4d 00 20 00 ff ; room &002
&41a4 51 40 3f 3f 3f 3f ff dd 03 05 33 81 ; room &003
&41b0 41 1d 3f 3f 3f 3f ff ec c0 b0 c3 81 ; room &004
&41bc 59 50 3f 3f 15 3f ff 11 06 00 c0 ff ; room &005
&41c8 51 4f 12 3f 14 3f ff 9b 3a 00 00 c7 ; room &006
&41d4 49 30 3f 3f 12 3f ff d1 30 00 0f c1 ; room &007
&41e0 78 5f 60 3f 2f 11 ff ba 60 00 4c 9c ; room &008
&41ec 51 40 3f 3f 12 3f ff 5a 30 08 00 ff ; room &009
&41f8 51 40 3f 3f 3f 3f ff 43 00 18 00 81 ; room &00a
&4204 59 5f 1f 3f 15 3f ff cb 04 01 03 c1 ; room &00b
&4210 41 1d 3f 3f 10 18 ff f1 a0 c4 c0 ff ; room &00c
&421c d8 53 5e 3f 28 3f ff b3 00 00 0f 2f ; room &00d
&4228 d8 50 7f 3f 14 3f ff a0 0a 00 ff ff ; room &00e
&4234 48 40 1a 25 16 3f ff 0f 18 38 f8 fc ; room &00f
&4240 c0 f0 2a 07 7f 2c c1 c0 c0 80 80 d0 ; room &010
&424c 41 10 3f 3f 3f 3f c7 40 08 00 03 9f ; room &011
&4258 49 36 1c 3f 3f 3f ff 07 03 01 ff ff ; room &012
&4264 41 10 3f 3f 3f 3f 81 81 c3 f1 c1 81 ; room &013
&4270 78 5f 40 3f 47 2c 41 80 80 80 c0 f0 ; room &014
&427c 41 10 3f 3f 3f 3f ff 07 03 0f 21 81 ; room &015
&4288 49 30 3f 3f 3f 3f c7 81 f9 c1 83 bf ; room &016
&4294 49 30 3f 3f 3f 3f c1 c1 e1 c1 83 81 ; room &017
&42a0 30 4f 51 3f 00 3f 5d 0c 6f 07 03 0f ; room &018
&42ac b0 30 6a 3f 40 0d 80 04 c0 80 90 ff ; room &019
&42b8 c1 10 bf 3f 28 3f 81 81 03 11 01 21 ; room &01a
&42c4 41 10 3f 3f 3f 3f c1 80 88 84 c0 f1 ; room &01b
&42d0 41 10 1b 3f 3f 3f ff 07 01 09 03 ff ; room &01c
&42dc 78 5f 61 3f 40 08 af 49 01 01 21 07 ; room &01d
&42e8 50 40 1d 3f 3f 3f ff 90 80 83 f0 e1 ; room &01e
&42f4 48 34 25 13 17 06 fc 04 0a 89 3b ff ; room &01f
&4300 50 40 3f 3f 3f 3f ff 89 81 81 89 99 ; room &020
&430c b0 3f 43 1c c0 da 50 80 c0 c0 f8 ff ; room &021
&4318 d9 50 bf 3f 28 3f ff 05 03 11 03 23 ; room &022
&4324 d9 4f a6 3f 87 2f 80 94 c0 a8 82 90 ; room &023
&4330 b0 f0 5c 0f 46 2e fe a5 84 9e 8c 8c ; room &024
&433c 59 53 0c 3f 3f 3f 81 80 3c 00 00 ff ; room &025
&4348 49 30 3f 3f 3f 3f bf 0b 05 01 03 c7 ; room &026
&4354 79 50 bf 3f 2c 3f 81 80 fc c0 80 80 ; room &027
&4360 d8 3f 40 15 52 1b cf 03 33 1b 07 ff ; room &028
&436c 48 30 dc ff 3f 3f ff c7 c3 87 c1 81 ; room &029
&4378 a8 f0 2a 14 7f 07 c1 c0 cc e0 c0 df ; room &02a
&4384 70 ff 6a 26 40 07 89 00 00 00 02 c0 ; room &02b
&4390 41 10 3f 3f 3f 3f ff 16 20 18 f0 ff ; room &02c
&439c 28 4f 68 3f 00 3f a7 07 07 0f 07 c3 ; room &02d
&43a8 40 10 2e 3f 3f 3f e1 80 83 81 81 ff ; room &02e
&43b4 58 22 1d 1b 3f 3f ff 09 c1 eb c1 c1 ; room &02f
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&51b8 98 0e d1 ff 06 3f c3 09 01 21 01 cf ; room &15a
&51c4 4a 3d 1a 1d 3f 3f ff 80 80 a0 a4 81 ; room &15b
&51d0 4a 00 3f 3f 3f 3f ff 01 01 05 21 81 ; room &15c
&51dc 4a 00 3f 3f 3f 3f ff 80 80 80 80 81 ; room &15d
&51e8 4a 00 3f 3f 3f 3f ff 01 01 01 01 81 ; room &15e
&51f4 52 00 3f 3f 3f 3f 81 b1 81 8d 81 81 ; room &15f
&5200 44 07 1a 3f 3f 3f 81 81 c1 81 b9 e1 ; room &160
&520c 54 0d da ff 1c 3f ff a9 81 83 81 81 ; room &161
&5218 4d 0d d2 ff 14 3f 81 81 a9 83 a9 81 ; room &162
&5224 45 00 3f 3f 3f 3f ff 80 92 80 a4 81 ; room &163
&5230 5d 00 1b 3f 3f 3f ff 05 01 31 01 81 ; room &164
&523c 83 3e 14 0c 3f 3f 81 80 80 80 80 81 ; room &165
&5248 53 e3 1b 23 3f 3f ff 01 01 01 01 81 ; room &166
&5254 44 0d e2 ff 24 3f ff a9 81 83 81 81 ; room &167
&5260 3d 2e ca d9 cd de 81 81 81 81 81 81 ; room &168
&526c 58 0d da ff 24 3f ff 83 83 83 83 c3 ; room &169
&5278 58 70 2a 1c 3f 3f cf 85 a5 85 9f ff ; room &16a
&5284 da ff 4b 15 5a 24 81 99 87 b1 8d 81 ; room &16b
&5290 5a 00 3f 3f 3f 3f 81 80 80 80 80 ff ; room &16c
&529c 5a 00 2d 3f 3f 3f 81 01 01 01 01 ff ; room &16d
&52a8 5a 00 2b 3f 3f 3f 81 80 a4 80 80 ef ; room &16e
&52b4 52 06 0c 3f 3f 3f 81 01 0d 21 01 ff ; room &16f
&52c0 44 5d 12 1d 3f 3f e1 81 a0 80 a4 81 ; room &170
&52cc 54 02 cb ff 0d 3f 81 eb 01 01 01 ff ; room &171
&52d8 5d 02 da ff 1d 3f 81 81 81 db 81 81 ; room &172
&52e4 5d 6d 0a 0c 3f 3f 81 a1 8d 81 a1 83 ; room &173
&52f0 5d 09 ca ff 1c 3f 81 83 b1 81 cd 81 ; room &174
&52fc 8b de 04 1a 3f 3f 81 80 80 a0 fe ff ; room &175
&5308 4b 0e 03 3f 3f 3f 81 01 01 05 01 ff ; room &176
&5314 54 ff 13 15 22 24 81 c1 9f 81 bf 81 ; room &177
&5320 75 2e c2 de c5 d9 81 81 81 81 81 81 ; room &178
&532c 50 0d 0a 3f 3f 3f c3 a0 a0 80 84 81 ; room &179
&5338 42 d0 19 24 3f 3f ff 09 21 61 21 81 ; room &17a
&5344 ca ff 4a 0d 5e 24 81 b6 80 83 8c 81 ; room &17b
&5350 4a 30 29 13 3f 3f ff 01 01 01 3f ff ; room &17c
&535c 4a 6d 22 1c 3f 3f ff a1 81 83 8d 81 ; room &17d
&5368 4a 29 da e1 dc ff ff 80 80 80 bf 81 ; room &17e
&5374 4a 03 d9 ff 1b 3f ff 09 01 01 f1 81 ; room &17f
&5380 5c 33 e2 cb 1d 3f 81 80 90 80 84 a1 ; room &180
&538c 4c 90 68 1a ff db ff 49 01 03 71 ff ; room &181
&5398 55 22 e1 e3 e4 e6 81 db 81 81 a5 81 ; room &182
&53a4 55 0d 0a 3f 3f 3f 83 e0 c0 c4 e0 ff ; room &183
&53b0 4d d5 0b 0c 3f 3f 81 08 3c 00 00 ff ; room &184
&53bc 4c 00 1b 3f 3f 3f ff 42 00 08 00 81 ; room &185
&53c8 54 03 d9 ff 1e 3f ff 24 00 00 42 ff ; room &186
&53d4 5c f0 7f 12 3f 15 81 01 37 01 01 ff ; room &187
&53e0 2d 2e c2 d9 c5 de 81 81 81 81 81 bd ; room &188
&53ec 40 40 2b 11 3f 3f 81 81 81 c3 ef ff ; room &189
&53f8 52 99 ca cb dc dd 81 83 b1 81 cd 81 ; room &18a
&5404 ca 0f 4a 3f 55 1b 81 b0 86 98 80 ff ; room &18b
&5410 82 0e d3 ff 14 3f ff 00 00 00 00 81 ; room &18c
&541c 5a 0d ca ff 0c 3f 81 29 29 01 01 ff ; room &18d
&5428 4a 03 0b 3f 3f 3f 81 81 91 81 81 81 ; room &18e
&5434 4a 06 ca ff 1c 3f 81 83 b1 81 8d 81 ; room &18f
&5440 54 00 3f 3f 3f 3f a1 88 a2 88 80 ff ; room &190
&544c 4c 0d e2 ff 24 3f ff 29 01 03 01 81 ; room &191
&5458 5d 00 1b 3f 3f 3f 81 80 80 b8 80 81 ; room &192
&5464 55 dd da e4 1e 3f ff 3a 00 00 00 81 ; room &193
&5470 95 0e 14 3f 3f 3f ff 09 01 01 03 81 ; room &194
&547c 4c 99 ca cb dc dd 81 83 b1 81 cd 81 ; room &195
&5488 95 0e 12 3f 3f 3f ff 80 80 80 8c 81 ; room &196
&5494 55 03 d9 ff 1e 3f ff 18 00 00 42 c3 ; room &197
&54a0 5d 00 3f 3f 3f 3f bd 00 00 00 00 81 ; room &198
&54ac 4d d0 1b 24 3f 3f ff 41 09 39 01 81 ; room &199
&54b8 52 00 3f 3f 3f 3f 81 81 8f c0 8f 81 ; room &19a
&54c4 4a 0d 1c 3f 3f 3f ff 89 e1 03 e1 81 ; room &19b
&54d0 32 0e c3 ff 04 3f 91 81 81 c1 81 83 ; room &19c
&54dc 4a 9d 1c 1e 3f 3f ff 88 80 c0 83 ff ; room &19d
&54e8 52 03 1d 3f 3f 3f 81 01 01 01 85 81 ; room &19e
&54f4 42 99 cc cd da db 81 c1 8d 81 b3 81 ; room &19f
&5500 44 90 2e 1c ff db ff 98 80 c0 fc fd ; room &1a0
&550c 4c 83 ff ff d4 dc 81 01 01 01 29 81 ; room &1a1
&5518 5d 99 ca cb dc dd 81 80 b0 80 8c 81 ; room &1a2
&5524 55 00 3f 3f 3f 3f 81 08 40 11 04 81 ; room &1a3
&5530 95 0e 04 3f 3f 3f 89 01 01 83 21 81 ; room &1a4
&553c 4c 00 3f 3f 3f 3f 81 c1 99 83 99 c1 ; room &1a5
&5548 9d e2 c9 c2 d9 ff a1 80 80 80 8c 81 ; room &1a6
&5554 5d 03 db ff 1c 3f c3 42 42 42 5a c3 ; room &1a7
&5560 4d 00 3f 3f 3f 3f 81 00 00 00 00 81 ; room &1a8
&556c 4d 0d ca ff 0c 3f 81 29 01 01 29 81 ; room &1a9
&5578 4a 0d 1a 3f 3f 3f 81 99 81 a1 a5 81 ; room &1aa
&5584 4a 6d 1a 0c 3f 3f 81 80 8c a0 e0 ff ; room &1ab
&5590 4a e0 e9 c3 ff c4 83 00 00 00 3c ff ; room &1ac
&559c 4a 07 1c 3f 3f 3f ff 18 10 00 1f ff ; room &1ad
&55a8 52 03 ca ff 0d 3f 81 01 25 01 81 ff ; room &1ae
&55b4 52 05 db ff 0d 3f 81 81 85 81 91 81 ; room &1af
&55c0 54 33 d2 dc 16 3f ff 80 80 a2 88 81 ; room &1b0
&55cc 5c 00 28 3f 3f 3f 81 11 01 01 4f ff ; room &1b1
&55d8 4d 90 2d 1b ff de 81 80 80 80 f3 ff ; room &1b2
&55e4 4d 00 3f 3f 3f 3f 81 00 18 00 81 ff ; room &1b3
&55f0 4d 0e 04 3f 3f 3f 89 03 01 01 f1 ff ; room &1b4
&55fc 54 6d 12 0c 3f 3f c1 81 ad 83 b1 81 ; room &1b5
&5608 2d 0e 02 1d 3f 3f 81 80 80 82 f0 81 ; room &1b6
&5614 5d 0d d9 ff 1e 3f c3 42 00 00 00 81 ; room &1b7
&5620 a5 00 7f 3f 1b 3f 81 00 00 14 00 81 ; room &1b8
&562c 45 30 1b 0c 3f 3f 81 01 09 39 01 81 ; room &1b9
&5638 4a 0d dd ff 0a 3f 81 a5 81 81 a1 81 ; room &1ba
&5644 57 0d 12 3f 3f 3f ff 81 a1 85 a1 81 ; room &1bb
&5650 47 06 5a 3f 22 3f ff 80 80 84 a8 81 ; room &1bc
&565c 5f 03 da ff 1d 3f ff 01 01 01 25 81 ; room &1bd
&5668 47 0d 24 3f 3f 3f ff 80 80 a0 80 81 ; room &1be
&5674 cf 00 3f 3f 3f 3f 81 25 01 11 05 81 ; room &1bf
&5680 56 0d 1c 3f 3f 3f 81 80 c0 88 88 81 ; room &1c0
&568c 4e 3d 1c 1a 3f 3f ff 00 00 00 20 81 ; room &1c1
&5698 46 0d da ff 14 3f ff 00 00 22 20 ff ; room &1c2
&56a4 4e 9d 1a 1d 3f 3f ff 10 00 20 24 81 ; room &1c3
&56b0 56 d0 2b 16 3f 3f ff 04 04 20 0e ff ; room &1c4
&56bc 5e 90 2d 0a ff cd 81 01 25 01 01 ff ; room &1c5
&56c8 5d 6d 0a 0c 3f 3f 81 a0 ac a0 80 ff ; room &1c6
&56d4 5d 0d 1c 3f 3f 3f 81 18 00 40 00 ff ; room &1c7
&56e0 5d 90 2d 0a ff cd 81 00 24 00 00 ff ; room &1c8
&56ec 9d e3 0a 12 3f 3f 81 01 01 03 0f ff ; room &1c9
&56f8 5e f3 dd d2 8a 25 81 81 b1 81 87 81 ; room &1ca
&5704 4f df 52 0c 1e 3f 81 88 b0 83 88 81 ; room &1cb
&5710 47 d0 59 0c 1a 3f 81 09 09 31 01 ff ; room &1cc
&571c 4e 00 23 3f 3f 3f 81 81 81 a1 ad 81 ; room &1cd
&5728 47 d3 0d 0a 3f 3f 81 a1 85 81 a1 81 ; room &1ce
&5734 47 99 e3 ca e5 cc 81 81 a9 81 81 ff ; room &1cf
&5740 5e 50 2b 0a ff cd 81 80 a4 80 80 ff ; room &1d0
&574c 9e e3 5a 0c 3f 3f 81 01 01 03 21 ff ; room &1d1
&5758 5e 90 2f 1e ff e4 ff 88 88 c0 82 fe ; room &1d2
&5764 46 00 3f 3f 3f 3f 81 15 41 09 23 81 ; room &1d3
&5770 5e 6d 1a 1c 3f 3f ff 84 80 80 8c 81 ; room &1d4
&577c 56 03 da ff 1d 3f ff 00 00 00 24 81 ; room &1d5
&5788 56 d0 2b 12 3f 3f ff 01 01 01 05 ff ; room &1d6
&5794 46 00 3f 3f 3f 3f ff 80 84 80 a0 81 ; room &1d7
&57a0 46 55 9a 1d a5 22 ff 42 02 00 36 81 ; room &1d8
&57ac 56 0d e3 ff 14 3f ff 01 01 41 05 81 ; room &1d9
&57b8 5e 3f 9a 12 dd d5 81 81 81 b7 81 81 ; room &1da
&57c4 7f 03 da ff 0d 3f 81 80 84 80 a0 81 ; room &1db
&57d0 90 30 28 21 3f 3f ff 01 01 01 01 ff ; room &1dc
&57dc 5f a9 e1 da 26 3f 81 81 81 81 81 ff ; room &1dd
&57e8 b7 60 29 24 3f 3f 81 80 a4 80 80 ff ; room &1de
&57f4 48 00 3f 3f 3f 3f ff 01 01 01 01 81 ; room &1df
&5800 46 9d 9a 1d a2 25 ff 80 80 a0 b6 81 ; room &1e0
&580c 46 0a 12 3f 3f 3f ff 00 20 00 00 ff ; room &1e1
&5818 5e 1e 13 1d 3f 3f ff 61 61 0b 4b fb ; room &1e2
&5824 56 03 ca ff 0d 3f 81 80 bc 80 80 ff ; room &1e3
&5830 4e 00 2d 3f 3f 3f 81 05 21 01 01 ff ; room &1e4
&583c 46 3d 62 0d 3f 3f 81 80 e4 a0 80 81 ; room &1e5
&5848 4e 3d d3 d9 16 3f ff 14 04 00 44 ff ; room &1e6
&5854 5e 00 bf 3f e3 13 81 00 04 10 14 81 ; room &1e7
&5860 56 99 ca d4 15 3f 81 01 21 0d 01 ff ; room &1e8
&586c 46 99 d2 d3 d5 d4 81 80 80 bc 80 81 ; room &1e9
&5878 56 00 3f 3f 3f 3f 81 01 01 01 01 81 ; room &1ea
&5884 4f 9d 92 7f dc ff 81 80 a0 8a a0 81 ; room &1eb
&5890 5f 0d 1c 3f 3f 3f ff 01 01 21 01 81 ; room &1ec
&589c 57 90 2e 23 ff e4 ff 82 80 a2 80 fd ; room &1ed
&58a8 c0 93 ff db e7 dc ff 00 00 00 18 81 ; room &1ee
&58b4 88 93 60 23 ff e5 81 01 01 01 01 ff ; room &1ef
&58c0 46 33 4a 0d 52 15 81 80 b6 80 80 ff ; room &1f0
&58cc 56 35 e1 d9 e6 de ff 10 00 00 00 ff ; room &1f1
&58d8 5e 95 e1 d9 e6 de fb 42 00 00 00 ff ; room &1f2
&58e4 5e 0d 1e 3f 3f 3f ff 1a 08 08 08 ff ; room &1f3
&58f0 5e 6d d1 e4 16 3f ff 40 00 00 00 ff ; room &1f4
&58fc 56 99 e5 e4 e3 e2 81 19 01 01 01 ff ; room &1f5
&5908 46 90 2e 23 ff e4 ff 82 82 a0 80 fd ; room &1f6
&5914 56 65 27 23 ff 3f 81 01 01 01 01 ff ; room &1f7
&5920 5e d0 2e 1d 3f 3f ff 80 80 c0 80 fd ; room &1f8
&592c 4e 63 0d 24 3f 3f 81 01 25 21 21 ff ; room &1f9
&5938 56 05 e0 ea 27 3f 81 81 81 81 00 df ; room &1fa
&5944 50 f9 ca d2 8c 54 81 81 bd 81 81 ff ; room &1fb
&5950 40 60 2c 22 3f 3f 81 80 80 80 80 f7 ; room &1fc
&595c 88 53 d9 e1 de e6 ff 00 00 00 00 ff ; room &1fd
&5968 70 0a 12 3f 3f 3f 81 00 20 00 00 ff ; room &1fe
&5974 58 d0 ff da e9 dc ff 01 01 01 01 ff ; room &1ff

; tile_subtile_table
&5980 00 00 00 00 00 00 ; TILE_EMPTY

; tile_subtile_table
&5980 00 00 00 00 00 00 ; TILE_EMPTY
&5986 11 11 11 11 11 11 ; TILE_WALL_EARTH
&598c 11 11 11 11 10 01 ; TILE_WALL_WISPS
&5992 11 11 11 11 11 11 ; TILE_WALL_STONES
&5998 11 11 11 11 11 11 ; TILE_WALL_MOLECULES
&599e 11 11 11 11 11 11 ; TILE_WALL_SQUARES
&59a4 11 11 11 11 11 11 ; TILE_WALL_RECTANGLES
&59aa 11 11 11 11 11 11 ; TILE_SIGN
&59b0 11 11 11 11 11 11 ; TILE_WALL_TWIN
&59b6 71 17 11 11 11 11 ; TILE_HOPPER_PAD
&59bc 11 44 00 00 00 00 ; TILE_HORIZONTAL_GATE
&59c2 01 10 01 10 01 10 ; TILE_SPARK_GATE
&59c8 00 00 00 00 10 01 ; TILE_SPARK_HEAD
&59ce 11 00 11 00 11 00 ; TILE_MUSHROOM
&59d4 00 00 10 11 11 11 ; TILE_SKELETONAUT_LEFT
&59da 00 00 01 00 11 11 ; TILE_SKELETONAUT_RIGHT
&59e0 11 11 11 11 11 11 ; TILE_DOME
&59e6 00 00 20 02 20 02 ; TILE_SPIKE
&59ec 00 22 00 22 00 10 ; TILE_SPIKE_ON_LEDGE
&59f2 65 56 35 53 35 53 ; TILE_PIPE_CLOSED
&59f8 65 56 33 33 33 33 ; TILE_PIPE_BOTH
&59fe 65 56 33 53 33 53 ; TILE_PIPE_LEFT
&5a04 65 56 35 33 35 33 ; TILE_PIPE_RIGHT
&5a0a 11 11 33 33 33 33 ; TILE_PIPE_TOP
&5a10 11 11 11 11 11 11 ; TILE_STARS
&5a16 11 11 11 11 11 11 ; TILE_PLANT_HEAD
&5a1c 11 11 11 11 11 11 ; (unused)
&5a22 11 11 11 11 11 11 ; TILE_PLANT_FLOWER
&5a28 11 11 11 11 11 11 ; (unused)
&5a2e 11 11 11 11 11 11 ; TILE_PLANT_BRANCHES
&5a34 11 11 11 11 11 11 ; (unused)
&5a3a 11 11 11 11 11 11 ; TILE_HEXAGONS
&5a40 11 11 11 11 11 11 ; (unused)
&5a46 11 11 11 11 11 11 ; TILE_THREE_HEADED_DOME
&5a4c 11 11 11 11 11 11 ; TILE_WHEELED_WALL
&5a52 11 11 00 11 00 11 ; TILE_SPACE_LOCK_LEFT
&5a58 11 11 11 00 11 00 ; TILE_SPACE_LOCK_RIGHT
&5a5e 11 11 00 11 00 11 ; TILE_TELEPORT

; tile_sprites
; tile_sprite_01 TILE_WALL_EARTH
&5a64 d9 6f aa ba 4c b6 f9 06 6d 6e 76 d5 7d af ba 66
&5a74 59 55 2b 66 8d 31 46 9d 2b 22 9b cc 45 66 a6 bb
&5a84 dc b9 ce 54 e8 26 e2 dd b7 7e fe dd 39 37 a2 62

; tile_sprite_02 TILE_WALL_WISPS
&5a94 c0 3e 02 00 10 c0 00 70 90 5f 00 ef f0 09 00 88
&5aa4 00 7c 15 6c 8d 80 5f 00 04 11 4c 00 00 7c 02 71
&5ab4 13 00 00 00 5f 00 a7 08 81 00 e8 1b 0c 00 00 00

; tile_sprite_03 TILE_WALL_STONES
&5ac4 73 77 8b f6 d9 cd 7b 67 e8 de b3 d0 ff 16 3b ed
&5ad4 ff 06 e6 bd 61 ff 6f d9 ee 46 d1 ee ee c2 ee 8e
&5ae4 3b 61 ee 4f 9d f6 ff 06 ee 2c 77 6f f6 ff 06 f6

; tile_sprite_04 TILE_WALL_MOLECULES
&5af4 31 13 20 40 a0 18 01 00 01 d8 8c 80 20 77 02 42
&5b04 ee 04 02 31 01 39 13 80 00 a0 08 00 40 ee 04 18
&5b14 13 00 00 00 08 98 e4 4e 72 27 20 12 04 00 00 00

; tile_sprite_05 TILE_WALL_SQUARES
&5b24 30 33 33 00 e0 ee ee 00 11 01 ff ff ee 6e 66 06
&5b34 77 77 54 15 88 99 e0 ee 00 cc cc cc 00 ff ff ff
&5b44 11 01 00 00 ee 0e 77 77 e0 ee ee ee 00 00 00 00

; tile_sprite_06 TILE_WALL_RECTANGLES
&5b54 6e 6e 6e 4e 00 00 13 13 13 13 8b 88 00 60 62 62
&5b64 4d 0d 01 01 9b 9b 9b 9b 88 88 88 9b 62 62 62 62
&5b74 01 01 00 00 9b 1b 13 00 9b 9b 9b 13 00 00 00 00

; tile_sprite_07 TILE_SIGN
&5b84 a7 88 aa ff af aa ab 7f 4f 4d 45 ff 9e 9b 9d ff
&5b94 7e 01 00 00 70 1e 10 11 f0 87 80 88 e7 08 00 00
&5ba4 00 00 00 00 11 10 23 55 88 80 cc ee 00 00 00 00

; tile_sprite_08 TILE_WALL_TWIN
&5bb4 30 73 e7 cc b0 db ed a6 b0 7b f6 dd 80 c8 64 aa
&5bc4 ba fc 77 3b 6a ee dd bb ff ff 76 bb aa 6a c4 8a
&5bd4 34 13 00 00 77 cb 7b 03 dc 7b ca 08 84 08 00 00

; tile_sprite_09 TILE_HOPPER_PAD
&5be4 ae ee 0a aa 00 00 00 00 00 00 00 00 57 77 05 55
&5bf4 ae aa ba bb fc cc 7c 55 f3 bb 2f 22 57 55 d5 dd
&5c04 fb ee 7f 37 37 cc c3 ff ce 33 3c ff fd 77 ef ce

; tile_sprite_0a TILE_HORIZONTAL_GATE
&5c14 b7 ea dd 88 60 bf cf 00 60 df 3f 00 de 75 bb 11
&5c24 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
&5c34 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

; tile_sprite_0b TILE_SPARK_GATE
&5c44 60 bf ff 9f 00 00 00 00 00 00 00 00 60 df ff 9f
&5c54 28 ff 2f 98 00 80 00 00 00 10 00 00 41 ff 4f 91
&5c64 ff bf 6f 00 00 00 00 00 00 00 00 00 ff df 6f 00

; tile_sprite_0c TILE_SPARK_HEAD
&5c74 60 bf fb 43 00 00 00 00 00 00 00 00 60 bf fb 2c
&5c84 44 66 33 22 00 00 00 c8 00 00 00 31 22 66 cc 44
&5c94 11 01 00 00 63 95 98 07 ec fe ff 0e 88 08 00 00

; tile_sprite_0d TILE_MUSHROOM
&5ca4 30 55 bf 78 80 c4 a6 ce 00 00 00 00 00 00 00 00
&5cb4 50 85 05 55 80 48 08 88 00 00 00 00 00 00 00 00
&5cc4 55 99 ab d2 08 53 d7 6f 00 00 00 00 00 00 00 00

; tile_sprite_0e TILE_SKELETONAUT_LEFT
&5cd4 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
&5ce4 00 00 10 21 10 70 b7 d5 80 16 88 cc e0 69 7d a0
&5cf4 22 03 41 0b bd 7b 1e 8e dd cd f1 0e 55 45 44 85

; tile_sprite_0f TILE_SKELETONAUT_RIGHT
&5d04 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
&5d14 00 1e 5d 0d 00 00 00 00 00 00 00 00 00 00 00 00
&5d24 40 92 99 0a 31 23 45 e0 00 00 e8 02 00 00 d2 19

; tile_sprite_10 TILE_DOME
&5d34 00 11 22 44 f0 b7 db de f0 ef ad a5 00 88 cc ee
&5d44 aa 99 88 99 bb 77 ff 77 c5 a7 b5 a6 dd bb 77 bb
&5d54 aa cc aa 07 5b 5b 5b 0f c4 84 88 0f b5 b5 b5 0e

; tile_sprite_11 TILE_SPIKE
&5d64 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
&5d74 00 00 00 00 11 d9 75 37 00 b9 6a c6 00 00 00 00
&5d84 00 00 00 00 7d 73 d5 19 ef c4 b6 89 00 00 00 00

; tile_sprite_12 TILE_SPIKE_ON_LEDGE
&5d94 00 00 00 00 00 00 00 00 11 d9 75 37 00 b9 6a c6
&5da4 00 00 00 00 00 00 00 00 7d 73 d5 19 ef c4 b6 89
&5db4 00 00 00 00 00 00 00 00 30 32 01 00 e0 7f ff 00

; tile_sprite_13 TILE_PIPE_CLOSED
&5dc4 bb bb bb bb ef bd d9 cd 7f db b9 3b dd dd dd dd
&5dd4 bb bb bb bb ff ff ff ff ff ff ff ff dd dd dd dd
&5de4 bb bb bb bb ff ff ff ff ff ff ff ff dd dd dd dd

; tile_sprite_14 TILE_PIPE_BOTH
&5df4 bb bb bb db ef bd d9 cd 7f db b9 3b dd dd dd bd
&5e04 55 55 55 55 ff ff ff ff ff ff ff ff aa aa aa aa
&5e14 55 55 55 b5 ff ff ff ff ff ff ff ff aa aa aa da

; tile_sprite_15 TILE_PIPE_LEFT
&5e24 bb bb bb db ef bd d9 cd 7f db b9 3b dd dd dd dd
&5e34 55 55 55 55 ff ff ff ff ff ff ff ff dd dd dd dd
&5e44 55 55 55 b5 ff ff ff ff ff ff ff ff dd dd dd dd

; tile_sprite_16 TILE_PIPE_RIGHT
&5e54 bb bb bb bb ef bd d9 cd 7f db b9 3b dd dd dd bd
&5e64 bb bb bb bb ff ff ff ff ff ff ff ff aa aa aa aa
&5e74 bb bb bb bb ff ff ff ff ff ff ff ff aa aa aa da

; tile_sprite_17 TILE_PIPE_TOP
&5e84 ff ff f0 bf ff ff f0 ff ff ff f0 ff ff ff f0 df
&5e94 55 55 55 55 ff ff ff ff ff ff ff ff aa aa aa aa
&5ea4 55 55 55 b5 ff ff ff ff ff ff ff ff aa aa aa da

; tile_sprite_18 TILE_STARS
&5eb4 00 00 40 00 00 00 00 01 00 00 80 8c 00 00 00 00
&5ec4 00 00 10 00 00 00 00 00 00 00 20 00 00 02 00 00
&5ed4 00 00 20 27 00 20 00 00 00 00 00 00 00 00 00 04 

; tile_sprite_19 TILE_PLANT_HEAD
&5ee4 10 40 60 50 30 00 00 01 81 01 03 02 06 0c 09 03
&5ef4 08 60 b0 60 01 0f 2e aa 00 00 00 00 08 08 88 88
&5e04 01 02 02 02 03 03 01 01 17 0c 08 2a 3f 07 08 07
&5e14 aa 88 22 bb cf 0c 03 0f 00 88 cc 0c 00 0c 0c 04
&5e24 01 00 00 00 00 00 00 00 06 08 0d 06 06 03 00 00
&5e34 0d 07 0e 05 0f 0c 00 00 0c 08 08 08 00 00 00 00

; tile_sprite_1b TILE_PLANT_FLOWER
&5e44 00 00 06 09 0b 0c 0e 07 00 00 01 01 01 01 00 0a
&5e54 00 0d 0e 0e 0e 0e 0c 00 00 08 0c 0c 0c 04 00 ee
&5e64 07 03 03 01 00 00 00 00 0d 0d 0d 0e 0f 03 00 01
&5e74 1d 1d 0c 0c 0a 07 07 07 99 11 15 0e 0e 06 04 00
&5e84 00 00 00 10 10 10 00 40 01 01 c1 61 c1 00 00 00
&5e94 02 00 00 00 30 68 18 08 00 00 00 00 00 80 80 00

; tile_sprite_1d TILE_PLANT_BRANCHES
&5ea4 a0 60 20 00 40 50 70 20 00 60 50 b0 60 01 01 01
&5eb4 08 18 38 38 18 08 00 00 00 80 40 80 80 20 30 f0
&5ec4 03 06 0c 40 e0 50 40 20 09 0c 07 03 00 c0 60 c1
&5ed4 00 08 0f 07 04 0c 18 18 20 0e 0f 08 80 c0 40 40
&5ee4 00 70 c0 a0 c0 10 00 20 01 01 01 01 c1 41 41 80
&5ef4 00 00 00 60 70 40 20 08 20 20 a0 60 20 60 40 00

; tile_sprite_1f TILE_HEXAGONS
&6004 00 10 fe ff f7 ff ff 87 fe ff ff 1e 00 80 f7 ff
&6014 ff 1e 2e 01 f7 ff ff 87 fe ff ff 1e ff 87 47 08
&6024 21 1e 2e 01 47 08 48 87 2e 01 21 1e 48 87 47 08

; core_element_from_pocket_sound
;     chan  vol   pitch dur
&6034 10 00 f1 00 02 00 02 00

; restored_core_element_sound
;     chan  vol   pitch dur
&603c 11 00 00 00 ff 00 01 00

; player_firing_sound
;     chan  vol   pitch dur
&6044 12 00 01 00 3c 00 02 00

; enemy_materialising_sound
;     chan  vol   pitch dur
&604c 13 00 02 00 14 00 05 00

; player_falling_sound
;     chan  vol   pitch dur
&6054 12 00 03 00 64 00 01 00

; bridging_platform_sound
;     chan  vol   pitch dur
&605c 10 00 f9 00 02 00 01 00

; tile_sprite_21 TILE_THREE_HEADED_DOME
&6064 00 21 40 44 97 73 f0 4f de fe f0 2f 00 48 a0 2a
&6074 73 5d 3f 5d 5b 75 aa 1a ad ea 55 85 ec ab cf ab
&6084 20 01 00 00 74 03 99 09 f2 0e dd 0d 40 08 00 00

; tile_sprite_22 TILE_WHEELED_WALL
&6094 00 c0 de ad 00 10 d3 ad 00 c0 de ad 00 10 d3 2d
&60a4 6a 55 64 a6 3a 55 b1 2b 5a 45 45 a6 52 15 d9 2b
&60b4 db ed cc 89 d6 3d 99 0c db ed cc 89 d6 3d 99 0c

; tile_sprite_23 TILE_SPACE_LOCK_LEFT
&60c4 33 ed ee 40 ff 0f ff 10 cc 7b 56 f0 f0 70 ff 70
&60d4 88 88 88 88 00 00 00 00 ae ae ae ee ce 89 ed ff
&60e4 88 88 88 48 00 00 00 10 ea ee aa ea f9 8f 8b ff

; tile_sprite_24 TILE_SPACE_LOCK_RIGHT
&60f4 f0 e0 ff e0 33 ed a6 f0 ff 0f ff 80 cc 7b 77 20
&6104 b7 91 73 ff 57 57 57 77 00 00 00 00 11 11 11 11
&6114 9f ff d1 f1 75 77 55 75 00 00 00 80 11 11 11 21 

; tile_sprite_25 TILE_TELEPORT
&6124 00 33 66 55 dd ff 88 44 ff 88 77 ff ff ff 00 10
&6134 ff 11 ee ff ff ff 33 d1 00 cc 66 aa bb ff 11 11
&6144 88 88 88 88 88 88 88 88 00 00 00 00 00 00 00 00
&6154 e0 a0 e0 a0 e0 a0 e0 e0 bb bb bb ff dd dd dd dd
&6164 88 88 88 88 88 88 88 44 00 00 00 00 00 00 00 10
&6174 a0 e0 e0 e0 a0 a0 a0 e0 dd dd dd dd dd dd dd dd

; unused
&6184 00

; rooms_with_patrolling_droids
&6185 b3 4b ; room &1b3
&6187 0b 4b ; room &10b
&6189 86 4b ; room &186
&618b dc 4b ; room &1dc
&618d fb 4b ; room &1fb
&618f fd 4b ; room &1fd
&6191 ff 4b ; room &1ff
&6193 ff 4b ; room &1ff (repeated)
&6195 de 49 ; room &1de
&6197 cf 4b ; room &1cf
&6199 9d 4b ; room &19d
&619b ae 4b ; room &1ae
&619d d2 4b ; room &1d2
&619f f2 4b ; room &1f2
&61a1 f1 4b ; room &1f1
&61a3 b1 49 ; room &1b1
&61a5 81 8a ; room &181
&61a7 f8 4b ; room &1f8
&61a9 f6 2b ; room &1f6

; gate_sprite
&61ab 77 33 55 22 ee cc aa 44 11 32 23 11 88 c4 4c 88
&61bb 22 55 33 77 44 aa cc ee

; gate_table
&61c3 be 78 ; room &0be
&61c5 fc 88 ; room &0fc
&61c7 c4 a9 ; room &1c4
&61c9 e6 a9 ; room &1e6
&61cb e2 29 ; room &1e2

; possible_core_element_locations
&61cd 08 4e 28 40 ; room &008 or room &028, ITEM_PASS               # ITEM_PASS can occur in one of four rooms
&61d1 a8 2a b6 46 ; room &0a8 or room &0b6, ITEM_PASS
&61d5 96 22 c6 46 ; room &096 or room &0c6, ITEM_KEY                # ITEM_KEY can occur in one of four rooms
&61d9 c8 34 f6 38 ; room &0c8 or room &0f6, ITEM_KEY
&61dd b4 4d a6 23 ; room &1b4 or room &1a6, core elements           # Core elements can occur in one of two rooms
&61e1 ec 02 de 2a ; room &0ec or room &0de
&61e5 34 46 10 46 ; room &034 or room &010
&61e9 f6 25 f8 23 ; room &1f6 or room &1f8
&61ed 28 1b 3a 0b ; room &128 or room &13a
&61f1 48 2a 6a 40 ; room &048 or room &06a
&61f5 36 29 16 47 ; room &136 or room &116
&61f9 38 22 2a 46 ; room &038 or room &02a
&61fd a0 23 60 43 ; room &1a0 or room &160
&6201 8c 4c 0e 36 ; room &08c or room &00e
&6205 0a 33 3c 4f ; room &10a or room &13c
&6209 dc 4d e2 2d ; room &1dc or room &1e2
&620d 54 24 56 2c ; room &054 or room &056
&6211 de 4d 3e 4a ; room &1de or room &03e
&6215 50 4a 52 36 ; room &050 or room &052
&6219 e2 38 c2 42 ; room &0e2 or room &0c2
&621d 72 4e 74 40 ; room &072 or room &074
&6221 d2 23 74 33 ; room &1d2 or room &174

; teleport_data
;     -8 -7 -6 -5 -4 -3 -2 -1
;     password       tl rm xy
&6225 52 4f 47 41 4c cc 1f 36 ; room &01f, "ROGAL"
&622d 56 49 4c 47 41 cc 28 3a ; room &028, "VILGA"
&6235 54 41 4d 49 53 cc 42 3a ; room &042, "TAMIS"
&623d 41 53 4f 47 45 cc 96 3a ; room &096, "ASOGE"
&6245 44 41 52 41 51 cc a2 3a ; room &0a2, "DARAQ"
&624d 51 55 41 52 4b cc d5 3a ; room &0d5, "QUARK"
&6255 53 41 4d 41 4c cc 21 3b ; room &121, "SAMAL"
&625d 4c 45 58 49 41 cc 57 3b ; room &157, "LEXIA"
&6265 4b 4f 50 45 58 cc 7c 37 ; room &17c, "KOPEX"
&626d 55 52 49 41 48 cc b1 3b ; room &1b1, "URIAH"
&6275 48 41 52 49 41 cc c9 3b ; room &1c9, "HARIA
&627d 4f 4b 52 49 50 cc cd 3b ; room &1cd, "OKRIP
&6285 41 52 4c 4f 4e cc d6 3b ; room &1d6, "ARLON"
&628d 4d 49 53 45 53 cc f3 47 ; room &1f3, "MISES
&6295 4f 54 52 55 4e cc fa 4b ; room &1fa, "OTRUN"

; pipe_arrow_sprite
&629d 00 11 22 44 66 22 22 33 00 88 44 22 66 44 66 44 44 cc

; update_pipe_arrows
&62ad a9 00    LDA #&00
&62af 85 8b    STA &8b ; column_to_consider
; update_pipe_arrows_loop
&62b1 a4 8b    LDY &8b ; column_to_consider
&62b3 38       SEC
&62b4 b9 50 01 LDA &0150,Y ; pipe_arrow_columns_status
&62b7 e9 01    SBC #&01
&62b9 29 3f    AND #&3f
&62bb 99 50 01 STA &0150,Y ; pipe_arrow_columns_status
&62be 29 01    AND #&01
&62c0 d0 35    BNE &62f7 ; consider_next_pipe_arrow
&62c2 b9 50 01 LDA &0150,Y ; pipe_arrow_columns_status
&62c5 c9 0c    CMP #&0c                                             # If an even number between 0 and 10,
&62c7 10 2e    BPL &62f7 ; consider_next_pipe_arrow
&62c9 0a       ASL A
&62ca 0a       ASL A
&62cb 85 8e    STA &8e ; tmp                                        # consider the corresponding row between 0 and 5
&62cd 98       TYA
&62ce 65 8e    ADC &8e ; tmp
&62d0 aa       TAX
&62d1 bd 20 01 LDA &0120,X ; pipe_in_tile                           # and the tile in that row. Is it a pipe?
&62d4 f0 21    BEQ &62f7 ; consider_next_pipe_arrow
&62d6 b9 50 01 LDA &0150,Y ; pipe_arrow_columns_status              # If so, calculate the corresponding screen address
&62d9 85 8f    STA &8f ; screen_address_high
&62db 4a       LSR A
&62dc 65 8f    ADC &8f ; screen_address_high
&62de 69 6d    ADC #&6d
&62e0 85 8f    STA &8f ; screen_address_high
&62e2 98       TYA
&62e3 0a       ASL A
&62e4 0a       ASL A
&62e5 0a       ASL A
&62e6 0a       ASL A
&62e7 0a       ASL A
&62e8 69 08    ADC #&08
&62ea 85 8e    STA &8e ; screen_address_low
&62ec a9 9d    LDA #&9d
&62ee 85 8c    STA &8c ; sprite_address_low
&62f0 a9 62    LDA #&62 ; &629d = pipe_arrow_sprite
&62f2 85 8d    STA &8d ; sprite_address_high
&62f4 20 d4 65 JSR &65d4 ; plot_single_character_sprite             # Plot or unplot arrow on pipe
; consider_next_pipe_arrow
&62f7 e6 8b    INC &8b ; column_to_consider
&62f9 a5 8b    LDA &8b ; column_to_consider
&62fb c9 08    CMP #&08
&62fd d0 b2    BNE &62b1 ; update_pipe_arrows_loop
&62ff 60       RTS

; plot_player                                                       # Called with X = width, Y = height
&6300 a5 8e    LDA &8e ; screen_address_low
&6302 29 07    AND #&07
&6304 85 89    STA &89 ; row_in_group
&6306 8a       TXA
&6307 0a       ASL A
&6308 0a       ASL A
&6309 0a       ASL A
&630a 85 8a    STA &8a ; bytes_in_group
&630c 84 8b    STY &8b ; groups_to_plot
&630e a5 8e    LDA &8e ; screen_address_low
&6310 29 f8    AND #&f8
&6312 aa       TAX
&6313 a4 8f    LDY &8f ; screen_address_high
&6315 20 e0 65 JSR &65e0 ; calculate_subtile_address_from_screen_address
; store_player_subtiles
&6318 a2 00    LDX #&00
&631a a0 00    LDY #&00
; store_player_subtiles_loop
&631c b1 6b    LDA (&6b),Y ; subtile_address
&631e 29 02    AND #&02 ; SUBTILE_HIDE_PLAYER                       # Note if part of player is obscured by pipe
&6320 9d c8 01 STA &01c8,X ; player_subtiles
&6323 e8       INX
&6324 c8       INY                                                  # Move right one subtile
&6325 98       TYA
&6326 29 03    AND #&03
&6328 c9 03    CMP #&03                                             # Three subtiles wide
&632a d0 f0    BNE &631c ; store_player_subtiles_loop
&632c 98       TYA
&632d 18       CLC
&632e 69 1d    ADC #&1d                                             # Move down one subtile
&6330 a8       TAY
&6331 c0 60    CPY #&60                                             # Three subtiles high
&6333 30 e7    BMI &631c ; store_player_subtiles_loop
; plot_subtiles
&6335 a9 00    LDA #&00
&6337 85 87    STA &87 ; subtile_offset
; plot_subtiles_column_loop
&6339 a0 00    LDY #&00
&633b 38       SEC
&633c a5 8e    LDA &8e ; screen_address_low
&633e 29 07    AND #&07
&6340 85 88    STA &88 ; sprite_offset
&6342 a9 08    LDA #&08
&6344 e5 88    SBC &88 ; sprite_offset
&6346 85 88    STA &88 ; sprite_offset
; plot_top_subtiles_row_loop
&6348 a6 87    LDX &87 ; subtile_offset
&634a bd c8 01 LDA &01c8,X ; player_subtiles
&634d f0 04    BEQ &6353 ; plot_top_subtile                         # Is the subtile obscured?
&634f c8       INY                                                  # If so, move right a subtile 
&6350 4c 5e 63 JMP &635e ; skip_plotting_top_subtile
; plot_top_subtile
&6353 b1 8e    LDA (&8e),Y ; screen_address
&6355 51 8c    EOR (&8c),Y ; sprite_address
&6357 91 8e    STA (&8e),Y ; screen_address
&6359 c8       INY
&635a c4 88    CPY &88 ; sprite_offset
&635c d0 f5    BNE &6353 ; plot_top_subtile
&635e e6 87    INC &87 ; subtile_offset
; skip_plotting_top_subtile
&6360 98       TYA
&6361 18       CLC
&6362 69 07    ADC #&07
&6364 29 f8    AND #&f8
&6366 a8       TAY
&6367 a5 88    LDA &88 ; sprite_offset
&6369 69 08    ADC #&08
&636b 85 88    STA &88 ; sprite_offset
&636d c4 8a    CPY &8a ; bytes_in_group
&636f d0 d7    BNE &6348 ; plot_top_subtiles_row_loop
&6371 18       CLC
&6372 a5 8e    LDA &8e ; screen_address_low
&6374 69 f8    ADC #&f8
&6376 85 8e    STA &8e ; screen_address_low
&6378 a5 8f    LDA &8f ; screen_address_high
&637a 69 00    ADC #&00
&637c 85 8f    STA &8f ; screen_address_high
&637e a5 89    LDA &89 ; row_in_group
&6380 f0 36    BEQ &63b8 ; next_group                               # If sprite aligned with group, no bottom to plot
&6382 a0 00    LDY #&00
; plot_bottom_subtiles_row_loop
&6384 38       SEC
&6385 a9 08    LDA #&08
&6387 e5 89    SBC &89 ; row_in_group
&6389 85 88    STA &88 ; sprite_offset
&638b 98       TYA
&638c 05 88    ORA &88 ; sprite_offset
&638e a8       TAY
&638f a6 87    LDX &87 ; subtile_offset
&6391 bd c8 01 LDA &01c8,X ; player_subtiles                        # Is subtile obscured?
&6394 f0 0a    BEQ &63a0 ; plot_bottom_subtile
&6396 98       TYA                                                  # If so, move right a subtile
&6397 18       CLC
&6398 69 08    ADC #&08
&639a 29 f8    AND #&f8
&639c a8       TAY
&639d 4c ac 63 JMP &63ac ; skip_plotting_bottom_subtile
; plot_bottom_subtile
&63a0 b1 8e    LDA (&8e),Y ; screen_address
&63a2 51 8c    EOR (&8c),Y ; sprite_address
&63a4 91 8e    STA (&8e),Y ; screen_address
&63a6 c8       INY
&63a7 98       TYA
&63a8 29 07    AND #&07
&63aa d0 f4    BNE &63a0 ; plot_bottom_subtile
; skip_plotting_bottom_subtile
&63ac e6 87    INC &87 ; subtile_offset
&63ae c4 8a    CPY &8a ; bytes_in_group
&63b0 d0 d2    BNE &6384 ; plot_bottom_subtiles_row_loop
&63b2 c6 87    DEC &87 ; subtile_offset
&63b4 c6 87    DEC &87 ; subtile_offset
&63b6 c6 87    DEC &87 ; subtile_offset
; next_group
&63b8 18       CLC
&63b9 a5 8e    LDA &8e ; screen_address_low
&63bb 69 08    ADC #&08
&63bd 85 8e    STA &8e ; screen_address_low
&63bf a5 8f    LDA &8f ; screen_address_high
&63c1 69 00    ADC #&00
&63c3 85 8f    STA &8f ; screen_address_high
&63c5 a5 8c    LDA &8c ; sprite_address_low
&63c7 65 8a    ADC &8a ; bytes_in_group
&63c9 85 8c    STA &8c ; sprite_address_low
&63cb 90 02    BCC &63cf ; skip_overflow
&63cd e6 8d    INC &8d ; sprite_address_high
; skip_overflow
&63cf c6 8b    DEC &8b ; groups_to_plot
&63d1 f0 03    BEQ &63d6 ; leave
&63d3 4c 39 63 JMP &6339 ; plot_subtiles_column_loop
; leave
&63d6 60       RTS

; unused
&63d7 00

; passage_data
&63d8 29 2c 2a 22 ; room &029 <-> room &02a
&63dc 33 4c 34 42 ; room &033 <-> room &034
&63e0 3d 2c 3e 22 ; room &03d <-> room &03e
&63e4 9a 4c 9b 42 ; room &09a <-> room &09b
&63e8 9d 48 9e 42 ; room &09d <-> room &09e
&63ec c2 44 c3 46 ; room &0c2 <-> room &0c3
&63f0 ec 4c ed 42 ; room &0ec <-> room &0ed
&63f4 f1 4c f2 22 ; room &0f1 <-> room &0f2
&63f6 69 2d 6a 3b ; room &169 <-> room &16a
&63fc 79 4c 7a 42 ; room &079 <-> room &07a

; spark_sprites
; spark_sprite_0
&6400 00 00 44 aa 11 00 00 00 00 00 44 aa 11 00 00 00
; spark_sprite_1
&6410 44 44 aa aa 22 11 11 00 44 44 aa aa 99 00 00 00
; spark_sprite_2
&6420 00 00 22 55 88 00 00 00 00 00 22 55 88 00 00 00
; spark_sprite_3
&6430 22 22 55 dd 99 00 00 00 22 22 55 55 44 88 88 00 

; rnd
&6440 a6 9a    LDX &9a ; rnd_1
&6442 a4 9b    LDY &9b ; rnd_2
&6444 06 9a    ASL &9a ; rnd_1
&6446 26 9b    ROL &9b ; rnd_2
&6448 8a       TXA
&6449 85 9d    STA &9d ; rnd_4
&644b 18       CLC
&644c 65 9a    ADC &9a ; rnd_1
&644e 08       PHP
&644f 18       CLC
&6450 69 03    ADC #&03
&6452 85 9a    STA &9a ; rnd_1
&6454 98       TYA
&6455 65 9b    ADC &9b ; rnd_2
&6457 28       PLP
&6458 65 9d    ADC &9d ; rnd_4
&645a 85 9b    STA &9b ; rnd_2
&645c 29 0f    AND #&0f
&645e 85 9c    STA &9c ; rnd_3
&6460 60       RTS

; update_sparks
&6461 a9 00    LDA #&00
&6463 85 88    STA &88 ; spark_offset
; update_sparks_loop
&6465 a6 88    LDX &88 ; spark_offset
&6467 bd 00 01 LDA &0100,X ; sparks_screen_address_low              # Is there a spark in this slot?
&646a d0 01    BNE &646d ; update_spark
&646c 60       RTS
; update_spark
&646d bd 04 01 LDA &0104,X ; sparks_frame
&6470 85 89    STA &89 ; spark_frame
&6472 dd 05 01 CMP &0105,X ; sparks_ignition_frame                  # Is the spark active?
&6475 30 09    BMI &6480 ; skip_unplotting_spark
&6477 29 03    AND #&03
&6479 c9 03    CMP #&03
&647b d0 03    BNE &6480 ; skip_unplotting_spark
&647d 20 d9 64 JSR &64d9 ; plot_spark                               # If so, unplot spark every four frames
; skip_unplotting_spark
&6480 18       CLC
&6481 a6 88    LDX &88 ; spark_offset
&6483 a5 89    LDA &89 ; spark_frame
&6485 69 01    ADC #&01
&6487 dd 06 01 CMP &0106,X ; sparks_total_frames
&648a 30 02    BMI &648e ; skip_overflow
&648c a9 00    LDA #&00
; skip_overflow
&648e 9d 04 01 STA &0104,X ; sparks_frame
&6491 85 89    STA &89 ; spark_frame
&6493 dd 05 01 CMP &0105,X ; sparks_ignition_frame
&6496 30 35    BMI &64cd ; consider_next_spark                      # Is the spark active?
&6498 29 03    AND #&03
&649a d0 03    BNE &649f ; skip_plotting_spark
&649c 20 d9 64 JSR &64d9 ; plot_spark                               # If so, replot spark every four frames
; skip_plotting_spark
&649f a6 88    LDX &88 ; spark_offset                               # Is the player touching the spark?
&64a1 a5 70    LDA &70 ; player_screen_address_low
&64a3 29 f8    AND #&f8
&64a5 38       SEC
&64a6 e9 10    SBC #&10
&64a8 dd 00 01 CMP &0100,X ; sparks_screen_address_low
&64ab b0 20    BCS &64cd ; consider_next_spark
&64ad 69 20    ADC #&20
&64af dd 00 01 CMP &0100,X ; sparks_screen_address_low
&64b2 90 19    BCC &64cd ; consider_next_spark
&64b4 d0 06    BNE &64bc ; check_y
&64b6 a5 72    LDA &72 ; player_sprite
&64b8 29 03    AND #&03
&64ba f0 11    BEQ &64cd ; consider_next_spark
; check_y
&64bc bd 01 01 LDA &0101,X ; sparks_screen_address_high
&64bf c5 71    CMP &71 ; player_screen_address_high
&64c1 90 0a    BCC &64cd ; consider_next_spark
&64c3 e9 03    SBC #&03
&64c5 c5 71    CMP &71 ; player_screen_address_high
&64c7 b0 04    BCS &64cd ; consider_next_spark
&64c9 a9 04    LDA #&04 ; TOUCHING_SPARK                            # If so, kill player
&64cb 85 20    STA &20 ; player_touching_death
; consider_next_spark
&64cd 18       CLC
&64ce a5 88    LDA &88 ; spark_offset
&64d0 69 08    ADC #&08                                             # Move to next spark
&64d2 85 88    STA &88 ; spark_offset
&64d4 29 20    AND #&20                                             # Maximum of four sparks
&64d6 f0 8d    BEQ &6465 ; update_sparks_loop
&64d8 60       RTS

; plot_spark
&64d9 a5 89    LDA &89 ; spark_frame
&64db 29 0c    AND #&0c
&64dd 0a       ASL A
&64de 0a       ASL A
&64df 85 8c    STA &8c ; sprite_address_low
&64e1 a9 64    LDA #&64 ; &6400 = spark_sprites
&64e3 85 8d    STA &8d ; sprite_address_high
&64e5 bd 00 01 LDA &0100,X ; sparks_screen_address_low
&64e8 85 8e    STA &8e ; screen_address_low
&64ea bd 01 01 LDA &0101,X ; sparks_screen_address_high
&64ed 85 8f    STA &8f ; screen_address_high
&64ef 4c d4 65 JMP &65d4 ; plot_single_character_sprite

; unused
&64f2 dd 99 bb 99 ff 00 ff 99 dd 99 dd 99 ff 00                     # Copy of &0a72 - &0a7f, end of font_data

; plot_aligned_sprite_using_write
&6500 84 8b    STY &8b ; height
&6502 8a       TXA
&6503 0a       ASL A
&6504 0a       ASL A
&6505 0a       ASL A
&6506 85 8a    STA &8a ; width
; plot_aligned_sprite_using_write_column_loop
&6508 a4 8a    LDY &8a ; width
&650a 88       DEY
; plot_aligned_sprite_using_write_row_loop
&650b b1 8c    LDA (&8c),Y ; sprite_address
&650d 91 8e    STA (&8e),Y ; screen_address
&650f 88       DEY
&6510 10 f9    BPL &650b ; plot_aligned_sprite_using_write_row_loop
&6512 e6 8f    INC &8f ; screen_address_high                        # Move down eight pixels
&6514 18       CLC
&6515 a5 8c    LDA &8c ; sprite_address_low
&6517 65 8a    ADC &8a ; width
&6519 85 8c    STA &8c ; sprite_address_low
&651b a5 8d    LDA &8d ; sprite_address_high
&651d 69 00    ADC #&00
&651f 85 8d    STA &8d ; sprite_address_high
&6521 c6 8b    DEC &8b ; height
&6523 d0 e3    BNE &6508 ; plot_aligned_sprite_using_write_column_loop
&6525 60       RTS

; plot_unaligned_sprite
&6526 a5 8e    LDA &8e ; screen_address_low
&6528 29 07    AND #&07
&652a 85 89    STA &89 ; row_in_group
&652c 8a       TXA
&652d 0a       ASL A
&652e 0a       ASL A
&652f 0a       ASL A
&6530 85 8a    STA &8a ; width
&6532 84 8b    STY &8b ; height
; plot_unaligned_sprite_group_loop
&6534 a0 00    LDY #&00
&6536 38       SEC
&6537 a5 8e    LDA &8e ; screen_address_low
&6539 29 07    AND #&07
&653b 85 88    STA &88 ; rows_to_plot
&653d a9 08    LDA #&08
&653f e5 88    SBC &88 ; rows_to_plot
&6541 85 88    STA &88 ; rows_to_plot
; plot_top_partial_group_loop
&6543 b1 8e    LDA (&8e),Y ; screen_address
&6545 51 8c    EOR (&8c),Y ; sprite_address
&6547 91 8e    STA (&8e),Y ; screen_address
&6549 c8       INY
&654a c4 88    CPY &88 ; rows_to_plot
&654c d0 f5    BNE &6543 ; plot_top_partial_group_loop
&654e 98       TYA
&654f 18       CLC
&6550 69 07    ADC #&07
&6552 29 f8    AND #&f8
&6554 a8       TAY
&6555 a5 88    LDA &88 ; rows_to_plot
&6557 69 08    ADC #&08
&6559 85 88    STA &88 ; rows_to_plot
&655b c4 8a    CPY &8a ; width
&655d d0 e4    BNE &6543 ; plot_top_partial_group_loop
&655f 18       CLC
&6560 a5 8e    LDA &8e ; screen_address_low
&6562 69 f8    ADC #&f8
&6564 85 8e    STA &8e ; screen_address_low
&6566 a5 8f    LDA &8f ; screen_address_high
&6568 69 00    ADC #&00
&656a 85 8f    STA &8f ; screen_address_high
&656c a5 89    LDA &89 ; row_in_group
&656e f0 1f    BEQ &658f ; skip_bottom_partial_group                # If sprite aligned with group, no bottom to plot
&6570 a0 00    LDY #&00
; plot_bottom_partial_group_column_loop
&6572 38       SEC
&6573 a9 08    LDA #&08
&6575 e5 89    SBC &89 ; row_in_group
&6577 85 88    STA &88 ; rows_to_plot
&6579 98       TYA
&657a 05 88    ORA &88 ; rows_to_plot
&657c a8       TAY
; plot_bottom_partial_group_row_loop
&657d b1 8e    LDA (&8e),Y ; screen_address
&657f 51 8c    EOR (&8c),Y ; sprite_address
&6581 91 8e    STA (&8e),Y ; screen_address
&6583 c8       INY
&6584 84 87    STY &87 ; unused                                     # Unnecessary code
&6586 98       TYA
&6587 29 07    AND #&07
&6589 d0 f2    BNE &657d ; plot_bottom_partial_group_row_loop
&658b c4 8a    CPY &8a ; width
&658d d0 e3    BNE &6572 ; plot_bottom_partial_group_column_loop
; skip_bottom_partial_group
&658f 18       CLC
&6590 a5 8e    LDA &8e ; screen_address_low
&6592 69 08    ADC #&08
&6594 85 8e    STA &8e ; screen_address_low
&6596 a5 8f    LDA &8f ; screen_address_high
&6598 69 00    ADC #&00
&659a 85 8f    STA &8f ; screen_address_high
&659c a5 8c    LDA &8c ; sprite_address_low
&659e 65 8a    ADC &8a
&65a0 85 8c    STA &8c ; sprite_address_low
&65a2 a5 8d    LDA &8d ; sprite_address_high
&65a4 69 00    ADC #&00
&65a6 85 8d    STA &8d ; sprite_address_high
&65a8 c6 8b    DEC &8b ; height
&65aa d0 88    BNE &6534 ; plot_unaligned_sprite_group_loop
&65ac 60       RTS

; plot_aligned_sprite_using_eor
&65ad 84 8b    STY &8b ; height
&65af 8a       TXA
&65b0 0a       ASL A
&65b1 0a       ASL A
&65b2 0a       ASL A
&65b3 85 8a    STA &8a ; width
; plot_aligned_sprite_using_eor_column_loop
&65b5 a4 8a    LDY &8a ; width
&65b7 88       DEY
; plot_aligned_sprite_using_eor_row_loop
&65b8 b1 8e    LDA (&8e),Y ; screen_address
&65ba 51 8c    EOR (&8c),Y ; sprite_address
&65bc 91 8e    STA (&8e),Y ; screen_address
&65be 88       DEY
&65bf 10 f7    BPL &65b8 ; plot_aligned_sprite_using_eor_row_loop
&65c1 a5 8c    LDA &8c ; sprite_address_low
&65c3 65 8a    ADC &8a ; width
&65c5 85 8c    STA &8c ; sprite_address_low
&65c7 a5 8d    LDA &8d ; sprite_address_high
&65c9 69 00    ADC #&00
&65cb 85 8d    STA &8d ; sprite_address_high
&65cd e6 8f    INC &8f ; screen_address_high                        # Move down eight pixels
&65cf c6 8b    DEC &8b ; height
&65d1 d0 e2    BNE &65b5 ; plot_aligned_sprite_using_eor_column_loop
&65d3 60       RTS

; plot_single_character_sprite                                      # Plots 4 * 8 pixels
&65d4 a0 0f    LDY #&0f
; plot_single_character_sprite_loop
&65d6 b1 8e    LDA (&8e),Y ; screen_address
&65d8 51 8c    EOR (&8c),Y ; sprite_address
&65da 91 8e    STA (&8e),Y ; screen_address
&65dc 88       DEY
&65dd 10 f7    BPL &65d6 ; plot_single_character_sprite_loop
&65df 60       RTS

; calculate_subtile_address_from_screen_address
&65e0 86 6b    STX &6b ; subtile_address_low
&65e2 84 6c    STY &6c ; subtile_address_high
&65e4 46 6c    LSR &6c ; subtile_address_high
&65e6 66 6b    ROR &6b ; subtile_address_low
&65e8 46 6c    LSR &6c ; subtile_address_high
&65ea 66 6b    ROR &6b ; subtile_address_low
&65ec 46 6c    LSR &6c ; subtile_address_high
&65ee 66 6b    ROR &6b ; subtile_address_low
&65f0 a5 6c    LDA &6c ; subtile_address_high
&65f2 29 03    AND #&03
&65f4 09 04    ORA #&04
&65f6 85 6c    STA &6c ; subtile_address_high
&65f8 a8       TAY
&65f9 a6 6b    LDX &6b ; subtile_address_low
&65fb 60       RTS

; unused
&65fc 00 00

; unused_zero_one                                                   # Values used in unused code at &1975
&65fe 00
; unused_zero_two
&65ff 00

; status_section                                                    # Raw MODE 5 screen data
&6600 10 30 50 d0 e0 e0 f0 f0 f0 80 80 e0 e0 c0 40 70
&6610 c0 c0 91 91 91 91 c0 c0 00 00 ff 33 77 ff 00 00
&6620 00 00 ff ff ff ff 00 00 00 00 ff ff ff ff 00 00
&6630 00 00 ee aa 22 ee 00 00 00 00 ff 99 bb ff 00 00
&6640 00 00 ff ff ff ff 00 00 00 00 ff ff ff ff 00 00
&6650 00 00 ff ee cc ff 00 00 00 00 bb aa aa bb 00 00
&6660 00 00 ff 77 ff ff 00 00 00 00 ff ff ff ff 00 30
&6670 00 00 ff ff ff ff 00 40 00 00 ee aa 22 ee 00 00
&6680 00 00 ff 99 bb ff 00 00 00 00 ff ff ff ff 00 00
&6690 00 00 ff ff ff ff 00 00 00 00 ff ee cc ff 00 00
&66a0 00 00 bb aa aa bb 00 00 00 00 ff 77 ff ff 00 00
&66b0 00 00 ff ff ff ff 00 00 00 00 ff ff ff ff 00 00
&66c0 00 00 ee aa 22 ee 00 00 00 00 ff 99 bb ff 00 00
&66d0 00 00 ff ff ff ff 00 00 00 00 ff ff ff ff 00 00
&66e0 00 00 ff ee cc ff 00 00 30 30 98 98 98 98 30 00
&66f0 f0 10 10 70 70 30 20 e0 80 c0 a0 b0 70 70 f0 f0
&6700 b0 b0 a0 a0 80 80 f0 80 80 80 83 83 83 83 83 83
&6710 00 07 0f 0f 0f 08 0b 0a 00 0f 0f 0f 0f 00 0f 00
&6720 00 0f 0f 0f 0f 00 0f 00 00 0f 0f 0f 0f 00 0f 00
&6730 00 0f 0f 0f 0f 00 0f 00 00 0f 0f 0f 0f 00 0f 00
&6740 00 0f 0f 0f 0f 00 0f 00 00 0f 0f 0f 0f 00 0f 00
&6750 00 0f 0f 0f 0f 00 0e 02 00 0a 0a 0a 0a 0a 0a 0a
&6760 00 10 20 10 30 40 60 70 10 d0 f0 60 30 10 30 70
&6770 00 00 00 80 80 c0 c0 c0 00 0b 0a 0a 0b 0b 0b 08
&6780 00 0e 0a 0e 0a 0a 0e 00 00 00 00 00 00 00 00 00
&6790 00 00 00 aa aa ee aa aa 00 00 00 ee 44 44 44 ee
&67a0 00 00 00 00 00 00 00 00 00 05 05 05 05 05 05 05
&67b0 00 66 55 66 55 66 00 00 00 55 55 55 55 22 00 00
&67c0 00 66 55 66 55 66 00 00 00 66 55 66 55 66 00 00
&67d0 00 44 44 44 44 66 00 00 00 cc 88 cc 88 cc 00 00
&67e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
&67f0 10 10 14 14 14 14 14 14 d0 d0 50 50 10 10 f0 10
&6800 80 77 77 55 55 77 77 77 83 03 07 07 07 07 07 07
&6810 0a 0a 0a 0a 0a 0a 0a 0a 00 cc aa cc aa cc 00 00
&6820 00 aa aa 66 22 cc 00 00 00 55 55 66 55 55 00 00
&6830 00 33 22 33 22 22 00 00 00 33 aa 33 22 22 00 00
&6840 00 22 aa 22 aa aa 00 00 00 55 99 99 99 55 00 00
&6850 02 8a 02 8a 02 8a 02 02 0a 0a 0a 0a 0a 0a 0a 0a
&6860 70 70 30 30 50 40 30 00 f0 d0 a0 b0 80 30 70 00
&6870 c0 c0 80 00 80 80 00 00 08 0b 0b 08 0a 08 09 08
&6880 00 06 06 08 0a 00 04 00 00 00 00 22 33 22 22 22
&6890 00 00 00 aa aa aa aa 99 00 00 00 aa bb aa aa 22
&68a0 00 00 00 88 88 88 88 88 05 05 05 05 05 05 05 05
&68b0 00 00 00 00 00 00 00 00 33 22 33 22 33 00 00 00
&68c0 22 aa 22 aa 11 00 00 00 99 aa 99 88 33 00 00 00
&68d0 88 00 00 88 00 00 00 00 00 11 11 00 00 00 00 00
&68e0 00 22 55 22 55 22 00 00 00 77 11 11 22 22 00 00
&68f0 14 04 06 06 06 06 06 06 10 ee ee aa aa ee ee ee
&6900 77 77 77 77 55 55 77 77 07 07 07 07 07 07 07 03
&6910 0a 0b 08 08 0f 0f 0f 0f 00 0f 00 00 0f 0f 0e 0e
&6920 00 0f 00 00 0f 0f 0f 0f 00 0f 00 00 0f 0f 03 02
&6930 00 0f 00 00 0f 0f 0f 07 00 0f 00 00 0f 0f 0f 0f
&6940 00 0f 00 00 0f 0f 0f 0f 00 0f 00 00 0f 0f 0d 0d
&6950 02 0e 00 00 0f 0f 0f 0f 0a 0a 0a 0a 0a 0a 0a 0a
&6960 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
&6970 00 00 00 00 00 00 00 00 08 08 09 0b 0a 08 08 08
&6980 00 04 04 0e 0a 0a 02 00 00 00 00 00 00 00 00 00
&6990 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
&69a0 00 00 00 00 00 00 00 00 05 05 04 04 05 05 05 05
&69b0 00 0f 00 00 0f 0f 0f 0f 00 0f 00 00 0f 00 07 0f
&69c0 00 0f 00 00 0f 07 07 07 00 0f 00 00 0f 0f 0f 0f
&69d0 00 0f 00 00 0f 0f 0f 0f 00 0f 00 00 0f 0e 0e 0e
&69e0 00 0f 00 00 0f 00 0e 0f 00 0f 00 00 0f 0f 0f 0f
&69f0 06 06 06 06 0e 0e 0e 0c ee ee ee ee aa aa ee ee
&6a00 80 80 f0 80 80 a0 a0 b0 83 83 83 83 83 80 80 70
&6a10 0f 0f 0f 0f 0f 03 01 c0 0e 0e 0e 0f 0f 0f 0f 00
&6a20 0f 0f 03 0f 0f 0f 0f 00 02 02 02 02 0f 0f 0f 00
&6a30 04 04 04 04 0f 0f 0f 00 0f 09 09 09 0f 0f 0f 00
&6a40 0f 0f 03 03 0f 0f 0f 00 0d 0d 01 0f 0f 0f 0f 00
&6a50 0f 0f 0f 0f 0f 0f 0f 00 0a 0a 0b 08 08 0f 0f 00
&6a60 00 00 0f 00 00 0f 0f 00 00 00 0f 00 00 0f 0f 00
&6a70 00 00 0e 00 00 0f 0f 00 08 08 0f 00 00 0f 0f 00
&6a80 00 00 0f 00 00 0f 0f 00 00 00 0f 00 00 0f 0f 00
&6a90 00 00 0f 00 00 0f 0f 00 00 00 0f 00 00 0f 0f 00
&6aa0 00 00 0f 00 00 0f 0f 00 05 05 0d 01 01 0f 0f 00
&6ab0 0f 0e 0c 0e 0e 0e 0f 00 07 03 01 03 03 03 0f 00
&6ac0 07 07 07 02 0f 0f 0f 00 0f 0f 0f 09 0f 0f 0f 00
&6ad0 0f 0f 0f 01 0f 0f 0f 00 0e 0e 0e 00 0f 0f 0f 00
&6ae0 0c 0c 0c 08 0c 0e 0f 00 07 07 07 03 07 0c 08 30
&6af0 1c 1c 1c 1c 1c 10 10 e0 10 10 f0 10 10 50 50 d0
&6b00 b0 e0 e0 d0 50 30 10 00 40 c0 e0 e0 80 80 f0 00
&6b10 c0 91 91 91 91 c0 c0 00 00 ff 33 77 ff 00 00 00
&6b20 00 ff ff ff ff 00 00 00 00 ff ff ff ff 00 00 00
&6b30 00 ee aa 22 ee 00 00 00 00 ff 99 bb ff 00 00 00
&6b40 00 ff ff ff ff 00 00 00 00 ff ff ff ff 00 00 00
&6b50 00 ff ee cc ff 00 00 00 00 bb aa aa bb 00 00 00
&6b60 00 ff 77 ff ff 00 00 00 00 ff ff ff ff 00 00 00
&6b70 00 ff ff ff ff 00 00 00 00 ee aa 22 ee 00 00 00
&6b80 00 ff 99 bb ff 00 00 00 00 ff ff ff ff 00 00 00
&6b90 00 ff ff ff ff 00 00 00 00 ff ee cc ff 00 00 00
&6ba0 00 bb aa aa bb 00 00 00 00 ff 77 ff ff 00 00 00
&6bb0 00 ff ff ff ff 00 00 00 00 ff ff ff ff 00 00 00
&6bc0 00 ee aa 22 ee 00 00 00 00 ff 99 bb ff 00 00 00
&6bd0 00 ff ff ff ff 00 00 00 00 ff ff ff ff 00 00 00
&6be0 00 ff ee cc ff 00 00 00 30 98 98 98 98 30 30 00
&6bf0 20 30 70 70 10 10 f0 00 d0 70 70 b0 a0 c0 80 00 

# &7000 - &72ff is decrypted to &0900 - &0bff at &752c

; font_data
&0900 70 66 ef ee 80 88 88 88 ; "A"
&0908 f0 dd df fd 80 88 80 88 ; "B"
&0910 f0 ee ee fe 80 08 00 88 ; "C"
&0918 f0 6e 66 fe 80 88 88 88 ; "D"
&0920 f0 fc ee ff 00 00 00 88 ; "E"
&0928 f0 fc ee ee 80 80 00 00 ; "F"
&0930 f0 cd dd fc 80 08 88 88 ; "G"
&0938 e0 ee ef ee 80 88 88 88 ; "H"
&0940 f0 77 77 f7 80 00 00 80 ; "I"
&0948 70 33 33 fb 80 88 88 88 ; "J"
&0950 e0 fe ff ee 80 88 80 88 ; "K"
&0958 e0 ee ee fe 00 00 00 80 ; "L"
&0960 f0 af 88 cc 80 88 88 88 ; "M"
&0968 e0 ee df cd 80 88 88 88 ; "N"
&0970 f0 ee ee fe 80 88 88 88 ; "O"
&0978 f0 ee ef ee 80 88 08 00 ; "P"
&0980 f0 dd fd fd 00 00 00 88 ; "Q"
&0988 f0 dd ef ee 00 00 88 88 ; "R"
&0990 f0 cd 0f ff 00 00 88 88 ; "S"
&0998 f0 77 77 77 80 00 00 00 ; "T"
&09a0 e0 ee ee fe 80 88 88 88 ; "U"
&09a8 e0 ee fe ef 80 88 88 00 ; "V"
&09b0 c0 8c aa ff 80 88 88 88 ; "W"
&09b8 e0 ee e7 ee 80 88 80 88 ; "X"
&09c0 e0 fe 7f 77 80 88 00 00 ; "Y"
&09c8 70 04 cf ff 80 88 08 88 ; "Z"
&09d0 00 00 00 00 00 00 00 00 ; " " ([)
&09d8 00 00 00 44 00 00 00 88 ; " " (~)
&09e0 00 00 22 00 00 00 00 00 ; "-" (])
&09e8 00 00 00 44 00 00 00 00 ; "." (^)
&09f0 00 00 00 00 00 00 00 00 ; " " (_)
&09f8 00 dc 63 9d 00 88 00 88 ; "%" (`)
&0a00 f0 bb bb fb 00 00 88 88 ; "0" (a)
&0a08 f0 77 f7 ff 00 00 80 88 ; "1" (b)
&0a10 f0 19 8f ff 80 88 08 88 ; "2" (c)
&0a18 f0 33 3f ff 00 00 88 88 ; "3" (d)
&0a20 b0 fb 3f 33 00 80 88 88 ; "4" (e)
&0a28 f0 8b 3f ff 00 00 88 88 ; "5" (f)
&0a30 f0 8b bf fb 00 00 88 88 ; "6" (g)
&0a38 f0 3b 33 33 00 00 88 88 ; "7" (h)
&0a40 f0 bb bf fb 00 88 88 88 ; "8" (i)
&0a48 f0 bb 3f 33 80 88 88 88 ; "9" (j)
&0a50 00 77 70 07 00 00 00 00 ; ":" (k)
&0a58 10 31 67 cc 80 08 00 00 ; "/" (l)
&0a60 00 00 00 ff 00 00 00 88 ; "_" (m)
; hopper_pad_numbers
&0a68 ff dd dd 99 99 99 ff 00 ; "1" (n)
&0a70 ff 99 dd 99 bb 99 ff 00 ; "2" (o)
&0a78 ff 99 dd 99 dd 99 ff 00 ; "3" (p)

; plot_text
&0a80 86 8e    STX &8e ; text_address_low
&0a82 84 8f    STY &8f ; text_address_high
; plot_text_loop
&0a84 a0 00    LDY #&00
&0a86 b1 8e    LDA (&8e),Y ; text_address
&0a88 f0 0b    BEQ &0a95 ; set_alignment
&0a8a 30 17    BMI &0aa3 ; set_colour                               # Top bit set to set colour
&0a8c c9 20    CMP #&20
&0a8e b0 43    BCS &0ad3 ; plot_character
&0a90 c9 1f    CMP #&1f
&0a92 f0 18    BEQ &0aac ; set_position                             # &1f to set screen address
&0a94 60       RTS
; set_alignment                                                     # Zero byte sets alignment of next character
&0a95 a5 87    LDA &87 ; alignment                                  # One zero byte = misaligned, two = aligned
&0a97 f0 03    BEQ &0a9c ; set_misalignment
&0a99 4c 12 0b JMP &0b12 ; set_alignment_and_move                   # Y = zero to indicate next character is aligned
; set_misalignment
&0a9c a9 01    LDA #&01                                             # Non-zero to indicate next character is misaligned
&0a9e 85 87    STA &87 ; alignment
&0aa0 4c 6c 0b JMP &0b6c ; consider_next_byte
; set_colour
&0aa3 a8       TAY
&0aa4 b9 f5 0a LDA &0af5,Y ; colour_mask_table - &80
&0aa7 85 89    STA &89 ; text_colour_mask
&0aa9 4c 6c 0b JMP &0b6c ; consider_next_byte
; set_position
&0aac c8       INY
&0aad b1 8e    LDA (&8e),Y ; text_address_low                       # Get a byte for x position
&0aaf 85 8a    STA &8a ; screen_address_low
&0ab1 0a       ASL A
&0ab2 65 8a    ADC &8a ; screen_address_low
&0ab4 48       PHA
&0ab5 29 f8    AND #&f8
&0ab7 85 8a    STA &8a ; screen_address_low
&0ab9 68       PLA
&0aba 29 04    AND #&04
&0abc 85 87    STA &87 ; alignment
&0abe c8       INY
&0abf b1 8e    LDA (&8e),Y ; text_address_low                       # Get a byte for y position
&0ac1 18       CLC
&0ac2 69 67    ADC #&67
&0ac4 85 8b    STA &8b ; screen_address_high
&0ac6 a5 8e    LDA &8e ; text_address_low
&0ac8 69 03    ADC #&03
&0aca 85 8e    STA &8e ; text_address_low
&0acc 90 02    BCC &0ad0 ; skip_overflow
&0ace e6 8f    INC &8f ; text_address_high
; skip_overflow
&0ad0 4c 84 0a JMP &0a84 ; plot_text_loop
; plot_character
&0ad3 84 8d    STY &8d ; text_offset
&0ad5 38       SEC
&0ad6 e9 41    SBC #&41 ; "A"
&0ad8 0a       ASL A
&0ad9 85 8c    STA &8c ; font_address_low
&0adb 06 8c    ASL &8c ; font_address_low
&0add 26 8d    ROL &8d ; font_address_high
&0adf 06 8c    ASL &8c ; font_address_low
&0ae1 26 8d    ROL &8d ; font_address_high
&0ae3 a5 8d    LDA &8d ; font_address_high
&0ae5 69 09    ADC #&09 ; &0900 = font_data
&0ae7 85 8d    STA &8d ; font_address_high
&0ae9 a2 10    LDX #&10
&0aeb 20 79 0b JSR &0b79 ; unpack_character
&0aee a0 00    LDY #&00
&0af0 a5 87    LDA &87 ; alignment                                  # Zero if character is aligned with column horizontally
&0af2 d0 2d    BNE &0b21 ; plot_misaligned_character_first_column_loop
; plot_aligned_character_first_column_loop
&0af4 b1 8c    LDA (&8c),Y ; unpacked_character_address             # Write four pixels to first column
&0af6 25 89    AND &89 ; text_colour_mask
&0af8 91 8a    STA (&8a),Y ; screen_address
&0afa c8       INY
&0afb c0 08    CPY #&08
&0afd d0 f5    BNE &0af4 ; plot_aligned_character_first_column_loop
; plot_aligned_character_second_column_loop
&0aff b1 8a    LDA (&8a),Y ; screen_address
&0b01 29 33    AND #&33 ; two rightmost pixels
&0b03 85 88    STA &88 ; screen_value
&0b05 b1 8c    LDA (&8c),Y ; unpacked_character_address             # Write two pixels to left of next column
&0b07 25 89    AND &89 ; text_colour_mask
&0b09 05 88    ORA &88 ; screen_value
&0b0b 91 8a    STA (&8a),Y ; screen_address
&0b0d c8       INY
&0b0e c0 10    CPY #&10                                             # Non-zero to indicate next character is misaligned
&0b10 d0 ed    BNE &0aff ; plot_aligned_character_second_column_loop
; set_alignment_and_move
&0b12 84 87    STY &87 ; alignment
&0b14 18       CLC
&0b15 a5 8a    LDA &8a ; screen_address_low
&0b17 69 08    ADC #&08                                             # Move right eight pixels
&0b19 85 8a    STA &8a ; screen_address_low
&0b1b 90 4f    BCC &0b6c ; consider_next_byte
&0b1d e6 8b    INC &8b ; screen_address_high
&0b1f b0 4b    BCS &0b6c ; consider_next_byte                       # Always branches
; plot_misaligned_character_first_column_loop
&0b21 b1 8c    LDA (&8c),Y ; unpacked_character_address             # Write two pixels to right of first column
&0b23 4a       LSR A
&0b24 4a       LSR A
&0b25 29 33    AND #&33 ; two rightmost pixels
&0b27 25 89    AND &89 ; text_colour_mask
&0b29 85 88    STA &88 ; font_value
&0b2b b1 8a    LDA (&8a),Y ; screen_address
&0b2d 29 cc    AND #&cc ; two leftmost pixels
&0b2f 05 88    ORA &88 ; font_value
&0b31 91 8a    STA (&8a),Y ; screen_address
&0b33 c8       INY
&0b34 c0 08    CPY #&08
&0b36 d0 e9    BNE &0b21 ; plot_misaligned_character_first_column_loop
; plot_misaligned_character_second_column_loop
&0b38 b1 8c    LDA (&8c),Y ; unpacked_character_address             # Get two pixels from one column of font data
&0b3a 4a       LSR A
&0b3b 4a       LSR A
&0b3c 25 89    AND &89 ; text_colour_mask
&0b3e 85 88    STA &88 ; font_value
&0b40 98       TYA
&0b41 49 08    EOR #&08
&0b43 a8       TAY
&0b44 b1 8c    LDA (&8c),Y ; unpacked_character_address             # Combine with two pixels from next column
&0b46 29 33    AND #&33 ; two rightmost pixels
&0b48 25 89    AND &89 ; text_colour_mask
&0b4a 0a       ASL A
&0b4b 0a       ASL A
&0b4c 05 88    ORA &88 ; font_value
&0b4e 85 88    STA &88 ; font_value
&0b50 98       TYA
&0b51 49 08    EOR #&08
&0b53 a8       TAY
&0b54 a5 88    LDA &88 ; font_value
&0b56 91 8a    STA (&8a),Y ; screen_address                         # Write to next screen column
&0b58 c8       INY
&0b59 c0 10    CPY #&10
&0b5b d0 db    BNE &0b38 ; plot_misaligned_character_second_column_loop
&0b5d 18       CLC
&0b5e a5 8a    LDA &8a ; screen_address_low
&0b60 69 10    ADC #&10                                             # Move right sixteen pixels
&0b62 85 8a    STA &8a ; screen_address_low
&0b64 90 02    BCC &0b68 ; skip_overflow
&0b66 e6 8b    INC &8b ; screen_address_high
; skip_overflow
&0b68 a0 00    LDY #&00                                             # Zero to indicate next character is aligned
&0b6a 84 87    STY &87 ; alignment
; consider_next_byte
&0b6c e6 8e    INC &8e ; text_address_low
&0b6e d0 02    BNE &0b72 ; skip_page
&0b70 e6 8f    INC &8f ; text_address_high
; skip_page
&0b72 4c 84 0a JMP &0a84 ; plot_text_loop

; colour_mask_table
;      0  1  2  3
&0b75 00 0f f0 ff

; unpack_character
&0b79 8e f5 0b STX &0bf5 ; character_size
&0b7c a2 00    LDX #&00
&0b7e a0 00    LDY #&00
; unpack_character_loop
&0b80 b1 8c    LDA (&8c),Y ; font_address
&0b82 29 0f    AND #&0f                                             # Low nibble
&0b84 8d f6 0b STA &0bf6 ; font_nibble
&0b87 0a       ASL A                                                # Multiply by 17 to use colour 3
&0b88 0a       ASL A
&0b89 0a       ASL A
&0b8a 0a       ASL A
&0b8b 0d f6 0b ORA &0bf6 ; font_nibble
&0b8e 9d c0 03 STA &03c0,X ; unpacked_character_buffer
&0b91 e8       INX
&0b92 b1 8c    LDA (&8c),Y ; font_address
&0b94 29 f0    AND #&f0                                             # High nibble
&0b96 8d f6 0b STA &0bf6 ; font_nibble
&0b99 4a       LSR A                                                # Divide by 16, then multiply by 17 to use colour 3
&0b9a 4a       LSR A
&0b9b 4a       LSR A
&0b9c 4a       LSR A
&0b9d 0d f6 0b ORA &0bf6 ; font_nibble
&0ba0 9d c0 03 STA &03c0,X ; unpacked_character_buffer
&0ba3 e8       INX
&0ba4 c8       INY
&0ba5 ec f5 0b CPX &0bf5 ; character_size
&0ba8 d0 d6    BNE &0b80 ; unpack_character_loop
&0baa a9 03    LDA #&03 ; &03c0 = unpacked_character_buffer
&0bac 85 8d    STA &8d ; unpacked_character_address
&0bae a9 c0    LDA #&c0
&0bb0 85 8c    STA &8c ; unpacked_character_address
&0bb2 60       RTS

; plot_packed_two_colour_sprite
&0bb3 86 8b    STX &8b ; colour_mask
&0bb5 84 8a    STY &8a ; screen_mask
&0bb7 0a       ASL A
&0bb8 0a       ASL A
&0bb9 0a       ASL A
&0bba 85 8c    STA &8c ; font_address_low
&0bbc 06 8c    ASL &8c ; font_address_low
&0bbe a9 00    LDA #&00
&0bc0 69 35    ADC #&35 ; &35e0 = packed_two_colour_sprite_data
&0bc2 48       PHA
&0bc3 a5 8c    LDA &8c ; font_address_low
&0bc5 69 e0    ADC #&e0
&0bc7 85 8c    STA &8c ; font_address_low
&0bc9 68       PLA
&0bca 69 00    ADC #&00
&0bcc 85 8d    STA &8d ; font_address_high
&0bce a2 20    LDX #&20
&0bd0 20 79 0b JSR &0b79 ; unpack_character
&0bd3 a2 00    LDX #&00
; plot_packed_two_colour_sprite_group_loop
&0bd5 a0 00    LDY #&00
; plot_packed_two_colour_sprite_row_loop
&0bd7 bd c0 03 LDA &03c0,X ; unpacked_character_buffer
&0bda 25 8b    AND &8b ; colour_mask
&0bdc 8d f6 0b STA &0bf6 ; sprite_byte
&0bdf b1 8e    LDA (&8e),Y ; screen_address
&0be1 25 8a    AND &8a ; screen_mask
&0be3 4d f6 0b EOR &0bf6 ; sprite_byte
&0be6 91 8e    STA (&8e),Y ; screen_address
&0be8 c8       INY
&0be9 e8       INX
&0bea c0 10    CPY #&10
&0bec d0 e9    BNE &0bd7 ; plot_packed_two_colour_sprite_row_loop
&0bee e6 8f    INC &8f ; screen_address_high
&0bf0 e0 20    CPX #&20
&0bf2 d0 e1    BNE &0bd5 ; plot_packed_two_colour_sprite_group_loop
&0bf4 60       RTS

; character_size
&0bf5 00

; font_nibble
; sprite_byte
&0bf6 00

; core_elements_colours
&0bf7 00 00 00 00 00 00 00 00 00

# &7300 - &73ff is decrypted to &7f00 - &7fff at &754a

; to_set_screen_colours
&7f00 4c b9 7f JMP &7fb9 ; set_screen_colours

; initialise_vectors
&7f03 a9 6f    LDA #&6f
&7f05 8d 20 02 STA &0220 ; event_vector_low
&7f08 a9 7f    LDA #&7f ; &7f6f = event_handler
&7f0a 8d 21 02 STA &0221 ; event_vector_high
&7f0d a9 0e    LDA #&0e ; Enable Event
&7f0f a2 04    LDX #&04 ; vsync event
&7f11 20 f4 ff JSR &fff4 ; OSBYTE
&7f14 78       SEI
&7f15 ad 07 02 LDA &0207 ; irq2_vector_high
&7f18 10 13    BPL &7f2d ; leave
&7f1a 8d fe 7f STA &7ffe ; previous_irq2_handler_high
&7f1d ad 06 02 LDA &0206 ; irq2_vector_low
&7f20 8d fd 7f STA &7ffd ; previous_irq2_handler_low
&7f23 a9 2f    LDA #&2f
&7f25 8d 06 02 STA &0206 ; irq2_vector_low
&7f28 a9 7f    LDA #&7f ; &7f2f = irq2_handler
&7f2a 8d 07 02 STA &0207 ; irq2_vector_high
; leave
&7f2d 58       CLI
&7f2e 60       RTS

; irq2_handler
&7f2f 08       PHP
&7f30 48       PHA
&7f31 8a       TXA
&7f32 48       PHA
&7f33 98       TYA
&7f34 48       PHA
&7f35 ad 6d fe LDA &fe6d ; User VIA interrupt flag register
&7f38 29 20    AND #&20                                             # User VIA timer 2 timeout
&7f3a f0 0d    BEQ &7f49 ; not_timer_2
&7f3c a2 00    LDX #&00
; write_palette_data_loop
&7f3e bd 0c 11 LDA &110c,X ; ula_palette_data + &10                 # Use palette for bottom section of screen
&7f41 8d 21 fe STA &fe21 ; video ULA palette register
&7f44 e8       INX
&7f45 e0 10    CPX #&10
&7f47 d0 f5    BNE &7f3e ; write_palette_data_loop
; not_timer_2
&7f49 a9 20    LDA #&20                                             # Disable User VIA timer 2 interrupts
&7f4b 8d 6e fe STA &fe6e ; User VIA interrupt enable register
&7f4e 68       PLA
&7f4f a8       TAY
&7f50 68       PLA
&7f51 aa       TAX
&7f52 68       PLA
&7f53 28       PLP
&7f54 6c fd 7f JMP (&7ffd) ; previous_irq2_handler

; set_timer
&7f57 ad 6b fe LDA &fe6b ; User VIA auxiliary control register
&7f5a 29 df    AND #&df                                             # Set User VIA timer 2 to timed interrupt
&7f5c 8d 6b fe STA &fe6b ; User VIA auxiliary control register
&7f5f a9 a0    LDA #&a0                                             # Enable interrupts for User VIA timer 2
&7f61 8d 6e fe STA &fe6e ; User VIA interrupt enable register
&7f64 a9 00    LDA #&00
&7f66 8d 68 fe STA &fe68 ; User VIA timer 2 counter LSB
&7f69 a9 0f    LDA #&0f
#     actually LDA timer2_msb
&7f6b 8d 69 fe STA &fe69 ; User VIA timer 2 counter MSB
&7f6e 60       RTS

; event_handler
&7f6f 08       PHP
&7f70 c9 04    CMP #&04
&7f72 d0 3b    BNE &7faf ; not_vsync
&7f74 48       PHA
&7f75 8a       TXA
&7f76 48       PHA
&7f77 98       TYA
&7f78 48       PHA
&7f79 a2 00    LDX #&00
; write_palette_data_loop
&7f7b bd fc 10 LDA &10fc,X ; ula_palette_data                       # Use palette for top (status) section of screen
&7f7e 8d 21 fe STA &fe21 ; video ULA palette register
&7f81 e8       INX
&7f82 e0 10    CPX #&10
&7f84 d0 f5    BNE &7f7b ; write_palette_data_loop
&7f86 20 57 7f JSR &7f57 ; set_timer
&7f89 c6 23    DEC &23 ; game_time_countdown
&7f8b a5 23    LDA &23 ; game_time_countdown
&7f8d d0 1a    BNE &7fa9 ; skip_overflow
&7f8f a9 32    LDA #&32
&7f91 85 23    STA &23 ; game_time_countdown
&7f93 f8       SED
&7f94 18       CLC
&7f95 a5 24    LDA &24 ; game_time_low
&7f97 69 01    ADC #&01
&7f99 85 24    STA &24 ; game_time_low
&7f9b d8       CLD
&7f9c c9 60    CMP #&60
&7f9e 90 09    BCC &7fa9 ; skip_overflow
&7fa0 a9 00    LDA #&00
&7fa2 85 24    STA &24 ; game_time_low
&7fa4 f8       SED
&7fa5 65 25    ADC &25 ; game_time_high
&7fa7 85 25    STA &25 ; game_time_high
; skip_overflow
&7fa9 d8       CLD
&7faa 68       PLA
&7fab a8       TAY
&7fac 68       PLA
&7fad aa       TAX
&7fae 68       PLA
; not_vsync
&7faf 28       PLP
&7fb0 60       RTS

; logical_colours
&7fb1 00 20 80 a0
; logical_colour_equivalents
&7fb5 00 10 40 50

; set_screen_colours
&7fb9 a9 07    LDA #&07
&7fbb 85 8c    STA &8c ; colour
&7fbd a9 10    LDA #&10                                             # &10 for bottom section of screen, &00 for top
&7fbf 85 8d    STA &8d ; section_offset
; set_screen_colours_loop
&7fc1 a4 8c    LDY &8c ; colour
&7fc3 b6 90    LDX &90,Y ; palette
&7fc5 98       TYA
&7fc6 4a       LSR A
&7fc7 a4 8d    LDY &8d ; section_offset
&7fc9 86 8e    STX &8e ; palette_value
&7fcb 85 8f    STA &8f ; physical_colour
&7fcd aa       TAX
&7fce bd b1 7f LDA &7fb1,X ; logical_colours
&7fd1 18       CLC
&7fd2 65 8e    ADC &8e ; palette_value
&7fd4 49 07    EOR #&07
&7fd6 85 8e    STA &8e ; actual_colour
&7fd8 98       TYA
&7fd9 06 8f    ASL &8f ; physical_colour
&7fdb 06 8f    ASL &8f ; physical_colour
&7fdd 18       CLC
&7fde 65 8f    ADC &8f ; physical_colour
&7fe0 a8       TAY
&7fe1 a2 00    LDX #&00
; calculate_ula_data_loop
&7fe3 18       CLC
&7fe4 a5 8e    LDA &8e ; actual_colour
&7fe6 7d b5 7f ADC &7fb5,X ; logical_colour_equivalents
&7fe9 99 fc 10 STA &10fc,Y ; ula_palette_data
&7fec e8       INX
&7fed c8       INY
&7fee e0 04    CPX #&04
&7ff0 d0 f1    BNE &7fe3 ; calculate_ula_data_loop
&7ff2 a5 8d    LDA &8d ; section_offset
&7ff4 49 10    EOR #&10
&7ff6 85 8d    STA &8d ; section_offset
&7ff8 c6 8c    DEC &8c ; colour
&7ffa 10 c5    BPL &7fc1 ; set_screen_colours_loop
&7ffc 60       RTS

; previous_irq2_handler_low
&7ffd 00
; previous_irq2_handler_high
&7ffe 00

; unused
&7fff 20

# &7400 - &74e7 is decrypted to &0440 - &0527 at &7569

; unused
&0440 00 00 00

; player_exploding_sound
; envelope
&0443 04 01 00 00 00 00 00 00 7e ff ff ff 7e 5a
;     chan  vol   pitch dur
&0451 00 00 04 00 06 00 01 00

; teleporting_sound
; envelope
&0459 04 01 f8 f0 e8 04 04 04 7e 00 00 82 7e 7e
;     chan  vol   pitch dur
&0467 11 00 04 00 c8 00 11 00

; tune_envelope
&046f 04 02 01 01 01 01 01 01 28 00 00 82 7e 7e

; tune_data
; title_tune
&047d 0a 06 03 2a 06 23 0b 08 03 2b 08 23 08 05 01 28
&048d 05 21 0a 06 01 2a 06 21 0a 06 03 2a 06 23 0b 08
&049d 03 2b 08 23 08 05 01 28 05 21 66 ff
; start_game_tune
&04a9 21 08 01 06 48 21 08 2b 4d 21 08 01 06 48 21 08
&04b9 26 44 21 08 01 06 48 21 08 2b 4d 21 08 01 06 48
&04c9 26 24 41 ff
; game_over_tune
&04cd 09 08 66 24 26 28 29 2d eb e8 09 08 66 24 26 28
&04dd 29 2d eb eb 0d 0b ad 26 28 29 2d 0b 09 ab 24 26
&04ed 28 2b 09 08 a9 21 26 28 29 e6 ff
; ending_tune
&04f8 01 08 4d 10 0f 4b 06 08 4b 06 08 4d 01 08 4d 0f
&0508 10 54 0f 0d 4b 06 08 4d 01 08 4d 10 0f 4b 06 08
&0518 4b 06 08 4d 01 08 4d 0f 10 54 0f 0d 4b 46 6d ff

# &74e8 - &75e7 is decrypted at &1500; &75e8 - &75ff is unencrypted

; decrypted_entry_point
&74e8 a9 8c    LDA #&8c ; Select Tape FS
&74ea a2 0c    LDX #&0c ; 1200 baud
&74ec 20 f4 ff JSR &fff4 ; OSBYTE
&74ef a9 c8    LDA #&c8 ; Read/Write BREAK/ESCAPE effect
&74f1 a2 03    LDX #&03 ; Clear memory on next RESET
&74f3 a0 00    LDY #&00
&74f5 20 f4 ff JSR &fff4 ; OSBYTE
&74f8 a9 04    LDA #&04 ; Define action of cursor editing keys
&74fa a2 01    LDX #&01 ; Cursor keys return ASCII values 135-139
&74fc a0 00    LDY #&00
&74fe 20 f4 ff JSR &fff4 ; OSBYTE
&7501 a9 0b    LDA #&0b ; Set auto-repeat delay
&7503 a2 00    LDX #&00 ; Disable auto-repeat
&7505 a0 00    LDY #&00
&7507 20 f4 ff JSR &fff4 ; OSBYTE
&750a a0 00    LDY #&00
&750c 84 8e    STY &8e ; source_address_low
&750e 84 8c    STY &8c ; target_address_low
&7510 a9 12    LDA #&12 ; &1200
&7512 85 8f    STA &8f ; source_address_high
&7514 a9 0e    LDA #&0e ; &0e00
&7516 85 8d    STA &8d ; target_address_high
; move_1200_to_6fff_loop                                            # Decrypt &1200 - &6fff and move to &0e00 - &6bff
&7518 98       TYA
&7519 49 ed    EOR #&ed
&751b 51 8e    EOR (&8e),Y ; source_address
&751d 91 8c    STA (&8c),Y ; target_address
&751f c8       INY
&7520 d0 f6    BNE &7518 ; move_1200_to_6fff_loop
&7522 e6 8d    INC &8d ; target_address_high
&7524 e6 8f    INC &8f ; source_address_low
&7526 a5 8f    LDA &8f ; source_address_low
&7528 c9 70    CMP #&70
&752a d0 ec    BNE &7518 ; move_1200_to_6fff_loop
; move_7000_to_72ff_loop                                            # Decrypt &7000 - &72ff and move to &0900 - &0bff
&752c 98       TYA
&752d 49 ed    EOR #&ed
&752f 59 00 70 EOR &7000,Y
&7532 99 00 09 STA &0900,Y
&7535 98       TYA
&7536 49 ed    EOR #&ed
&7538 59 00 71 EOR &7100,Y
&753b 99 00 0a STA &0a00,Y
&753e 98       TYA
&753f 49 ed    EOR #&ed
&7541 59 00 72 EOR &7200,Y
&7544 99 00 0b STA &0b00,Y
&7547 c8       INY
&7548 d0 e2    BNE &752c ; move_7000_to_72ff_loop
; move_7300_to_73ff_loop                                            # Decrypt &7300 - &73ff and move to &7f00 - &7fff
&754a 98       TYA
&754b 49 ed    EOR #&ed
&754d 59 00 73 EOR &7300,Y
&7550 99 00 7f STA &7f00,Y
&7553 c8       INY
&7554 d0 f4    BNE &754a ; move_7300_to_73ff_loop
&7556 98       TYA
; wipe_0400_to_07ff_loop                                            # Wipe &0400 - &07ff and &6c00 - &6cff
&7557 99 00 04 STA &0400,Y
&755a 99 00 05 STA &0500,Y
&755d 99 00 06 STA &0600,Y
&7560 99 00 07 STA &0700,Y
&7563 99 00 6c STA &6c00,Y
&7566 c8       INY
&7567 d0 ee    BNE &7557 ; wipe_0400_to_07ff_loop
; move_7400_to_74e7_loop                                            # Decrypt &7400 - &74e7 and move to &0440 - &0527
&7569 98       TYA
&756a 49 ed    EOR #&ed
&756c 59 00 74 EOR &7400,Y
&756f 99 40 04 STA &0440,Y
&7572 c8       INY
&7573 c0 e8    CPY #&e8
&7575 d0 f2    BNE &7569 ; move_7400_to_74e7_loop
&7577 a0 0a    LDY #&0a
; wipe_0000_to_00af_loop                                            # Wipe &0000 to &00af
&7579 a9 00    LDA #&00
&757b 99 00 00 STA &0000,Y
&757e c8       INY
&757f c0 b0    CPY #&b0
&7581 d0 f6    BNE &7579 ; wipe_0000_to_00af_loop
&7583 a0 07    LDY #&07
; move_75da_to_75e1_loop                                            # Move &75da - &75e1 to &0090 - &0097
&7585 b9 da 75 LDA &75da,Y ; unrelocated_palette
&7588 99 90 00 STA &0090,Y ; palette
&758b 88       DEY
&758c 10 f7    BPL &7585 ; move_75da_to_75e1_loop
&758e a5 00    LDA &00 ; loader_rnd_1
&7590 85 9a    STA &9a ; rnd_1
&7592 a5 01    LDA &01 ; loader_rnd_2
&7594 85 9b    STA &9b ; rnd_2
&7596 a9 9e    LDA #&9e ; Z
&7598 85 00    STA &00 ; key_left
&759a a9 bd    LDA #&bd ; X
&759c 85 01    STA &01 ; key_right
&759e a9 b7    LDA #&b7 ; *
&75a0 85 02    STA &02 ; key_up
&75a2 a9 97    LDA #&97 ; ?
&75a4 85 03    STA &03 ; key_down
&75a6 a9 b6    LDA #&b6 ; RETURN
&75a8 85 04    STA &04 ; key_fire
&75aa a5 07    LDA &07 ; user_defined_key_up
&75ac a6 08    LDX &08 ; user_defined_key_down
&75ae 85 08    STA &08 ; user_defined_key_down
&75b0 86 07    STX &07 ; user_defined_key_up
&75b2 c8       INY
; set_video_registers_loop
&75b3 b9 e2 75 LDA &75e2,Y ; video_register_table
&75b6 8d 00 fe STA &fe00 ; video register number
&75b9 c8       INY
&75ba b9 e2 75 LDA &75e2,Y ; video_register_table
&75bd 8d 01 fe STA &fe01 ; video register value
&75c0 c8       INY
&75c1 c0 0e    CPY #&0e
&75c3 d0 ee    BNE &75b3 ; set_video_registers_loop
&75c5 a9 9a    LDA #&9a ; Write to Video ULA control register and RAM copy
&75c7 a2 64    LDX #&64                                             # MODE 5, small cursor, 4 byte cursor
&75c9 20 f4 ff JSR &fff4 ; OSBYTE
&75cc 20 03 7f JSR &7f03 ; initialise_vectors
&75cf 20 00 7f JSR &7f00 ; to_set_screen_colours
&75d2 a9 0f    LDA #&0f ; Flush input buffer
&75d4 20 f4 ff JSR &fff4 ; OSBYTE
&75d7 4c 90 32 JMP &3290 ; title_screen

# &75da - &75e1 is moved to &0090 - &0097 at &7585

; palette
&0090 00 00 00 01 00 02 00 07

; video_register_table
&75e2 01 20 ; R1: Number of characters per line
&75e4 06 19 ; R6: Vertical displayed register
&75e6 0c 0c ; R12: Displayed screen start address register (high)   # Set screen start address to &6600
&75e8 0d c0 ; R13: Displayed screen start address register (low)
&75ea 07 24 ; R7: Vertical sync position
&75ec 02 2e ; R2: Horizontal sync position register
&75ee 00 3f ; R0: Horizontal total register

; unused
&75f0 ae 34 14 bb d2 d2 a6 f9 0d bb f2 a7 93 c9 a0 c0 3b            # Not meaningful encrypted or decrypted