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23 lines
450 B
Plaintext
23 lines
450 B
Plaintext
processor 6502
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seg program
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org $803
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.start
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sta $c050 ; set graphics
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sta $c052 ; no mixed mode
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sta $c057 ; set hires
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ldx #0
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.loop inc $2000,x ; increment hgr byte
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inx
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bne .loop
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lda .loop+2 ; increment hi byte of instruction
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clc
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adc #1
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sta .loop+2 ; self-modifying code
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cmp #$40
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bne .loop
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lda #$20 ; reset to $2000
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sta .loop+2
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jmp .start
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