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https://github.com/sehugg/8bitworkshop.git
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52 lines
1.0 KiB
Plaintext
52 lines
1.0 KiB
Plaintext
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processor 6502
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include "vcs.h"
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include "macro.h"
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include "xmacro.h"
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Variables segment
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seg.u Variables
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org $80
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Temp .byte
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Code segment
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seg Code
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org $f000
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Start
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CLEAN_START
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NextFrame
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lsr SWCHB ; test Game Reset switch
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bcc Start ; reset?
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; 1 + 3 lines of VSYNC
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VERTICAL_SYNC
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; 37 lines of underscan
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TIMER_SETUP 37
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TIMER_WAIT
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; 192 lines of frame
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TIMER_SETUP 192
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; draw colors based on timer value
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LRainbow
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lda INTIM ; load timer
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sta COLUBK ; store background
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bne LRainbow ; loop until timer == 0
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TIMER_WAIT ; timer is already 0, no-op
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; 29 lines of overscan
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TIMER_SETUP 29
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TIMER_WAIT
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; total = 262 lines, go to next frame
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jmp NextFrame
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Epilogue
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org $fffc
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.word Start ; reset vector
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.word Start ; BRK vector
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