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30 lines
849 B
Plaintext
30 lines
849 B
Plaintext
DELAYMS
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MSCNT EQU $0CA ; 202 TIMES THROUGH DELAY1
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; SPECIFIC TO 1.23 MHZ
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; SPEED OF APPLE II
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:DELAY
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CPY #0 ; 2 CYCLES
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BEQ :EXIT ; 2C (EXIT IF DEL=0)
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NOP ; 2 CYCLES (MAKE OVERHEAD=25C)
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CPY #1 ; 2 CYCLES
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BNE :DELAYA ; 3C IF TAKEN, ELSE 2C
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JMP :LAST1 ; 3C
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:DELAYA
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DEY ; 2C (PREDEC Y)
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:DELAY0
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LDX #MSCNT ; 2C
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:DELAY1
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DEX ; 2C
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BNE :DELAY1 ; 3C
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NOP ; 2C
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NOP ; 2C
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DEY ; 2C
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BNE :DELAY0 ; 3C
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:LAST1
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LDX #MSCNT-3 ; 2C
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:DELAY2
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DEX ; 2C
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BNE :DELAY2 ; 3C
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:EXIT
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RTS ; 6C
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