31 lines
1.7 KiB
Plaintext
31 lines
1.7 KiB
Plaintext
0000- 4
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0000- 5 * ----------------------------------------------------------------------
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0000- 6 * SIREN PROGRAM AS FOUND IN THE BOOK "6502 APPLICATIONS BOOK" BY RODNEY
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0000- 7 * ZAKS. ADAPTED FOR THE KIM-1 WITH THE 6502 PROJECT PLATFORM BOARD AND
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0000- 8 * COVOX PROJECT BOARD.
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0000- 9 *
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00D1- 10 DELAY .EQ $D1
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0000- 11
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1700- 12 VIA .EQ $1700
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1700- 13 IRB .EQ VIA
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1700- 14 ORA .EQ VIA + $1
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1700- 15 DDRB .EQ VIA + $2
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1700- 16 DDRA .EQ VIA + $3
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0000- 17
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0200- 18 .OR $0200
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0200- 19 .TA $0200
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0200- 20
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0200-A9 FF 21 ( 2) START LDA #$FF SET PORT A
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0202-8D 00 17 22 ( 4) STA DDRA AS OUTPUTS
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0205-85 D1 23 ( 2) STA DELAY INITIALIZE DELAY
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0207-A9 03 24 ( 2) LDA #$03 INITIALIZE VOLUME
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0209-8D 00 17 25 ( 4) STA ORA
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020C-A9 FF 26 ( 2) SWITCH LDA #$FF EXCLUSIVE OR WITH
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020E-4D 00 17 27 ( 4) EOR ORA MASK $FF IS USED
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0211-8D 00 17 28 ( 4) STA ORA TO INVERT OUTPUT.
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0214-A6 D1 29 ( 3) LDX DELAY
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0216-CA 30 ( 2) LOOP DEX
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0217-D0 FD 31 (2**) BNE LOOP
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0219-C6 D1 32 ( 5) DEC DELAY
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021B-4C 0C 02 33 ( 3) JMP SWITCH
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