55 lines
2.9 KiB
Plaintext
55 lines
2.9 KiB
Plaintext
0000- 4
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0000- 5 * ----------------------------------------------------------------------
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0000- 6 * PLAY A SINGLE NOTE USING TIMER1 ON 6522 (VIA) FOUND ON THE PROJECT
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0000- 7 * BOARD. REQUIRES INTERRUPT VECTOR CONFIGURED TO POINT TO INTR (SEE
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0000- 8 * LISTING).
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0000- 9 *
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00D0- 10 VOLUME .EQ $D0
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0000- 11
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00FB- 12 POINTH .EQ $FB DIGITS 1-2
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00FA- 13 POINTL .EQ $FA DIGITS 3-4
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00F9- 14 INH .EQ $F9 DIGITS 5-6
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1F1F- 15 SCANDS .EQ $1F1F
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0000- 16
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1700- 17 VIA .EQ $1700
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1700- 18 IRB .EQ VIA
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1700- 19 ORA .EQ VIA + $1
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1700- 20 DDRB .EQ VIA + $2
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1700- 21 DDRA .EQ VIA + $3
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1700- 22 T1CL .EQ VIA + $4
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1700- 23 T1CH .EQ VIA + $5
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1700- 24 ACR .EQ VIA + $B
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1700- 25 IER .EQ VIA + $E
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0000- 26
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0200- 27 .OR $0200
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0200- 28 .TA $0200
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0200- 29
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0200-A9 FF 30 ( 2) SETUP LDA #$FF SET PORT A
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0202-8D 00 17 31 ( 4) STA DDRA AS OUTPUTS
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0205-A9 FF 32 ( 2) TIMER LDA #$FF RESET TIMER1
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0207-8D 00 17 33 ( 4) STA T1CL
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020A-8D 00 17 34 ( 4) STA T1CH
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020D-A9 40 35 ( 2) LDA #$40 FREE-RUN MODE WITHOUT
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020F-8D 00 17 36 ( 4) STA ACR ENABLING OUTPUT ON PB7
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0212-A9 C0 37 ( 2) LDA #$C0 ENABLE VIA
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0214-8D 00 17 38 ( 4) STA IER INTERRUPT
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0217-58 39 ( 2) CLI ENABLE CPU INTERRUPT
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0218- 40
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0218-A9 E4 41 ( 2) SETNOTE LDA #$E4
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021A-8D 00 17 42 ( 4) STA T1CL
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021D-A9 17 43 ( 2) LDA #$17
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021F-8D 00 17 44 ( 4) STA T1CH
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0222- 45
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0222-A2 7F 46 ( 2) WAIT LDX #$7F
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0224-EA 47 ( 2) MORE NOP
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0225-CA 48 ( 2) DEX
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0226-D0 FC 49 (2**) BNE MORE
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0228-4C 22 02 50 ( 3) JMP WAIT
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022B- 51
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022B-A9 FF 52 ( 2) INTR LDA #$FF
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022D-45 D0 53 ( 3) EOR VOLUME
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022F-85 D0 54 ( 2) STA VOLUME
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0231-8D 00 17 55 ( 4) STA ORA
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0234-58 56 ( 2) CLI
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0235-40 57 ( 6) RTI
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