66 lines
3.5 KiB
Plaintext
66 lines
3.5 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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00D1- 11 TEMP .EQ $D1
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00D2- 12 OUTPUT .EQ $D2
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0000- 13
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0000- 14
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00FB- 15 POINTH .EQ $FB DIGITS 1-2
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00FA- 16 POINTL .EQ $FA DIGITS 3-4
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00F9- 17 INH .EQ $F9 DIGITS 5-6
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1F1F- 18 SCANDS .EQ $1F1F
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0000- 19
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1700- 20 VIA .EQ $1700
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1700- 21 IRB .EQ VIA
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1700- 22 ORA .EQ VIA + $1
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1700- 23 DDRB .EQ VIA + $2
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1700- 24 DDRA .EQ VIA + $3
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1700- 25 T1CL .EQ VIA + $4
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1700- 26 T1CH .EQ VIA + $5
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1700- 27 ACR .EQ VIA + $B
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1700- 28 IER .EQ VIA + $E
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0000- 29
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0200- 30 .OR $0200
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0200- 31 .TA $0200
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0200- 32
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0200-A9 FF 33 ( 2) SETUP LDA #$FF SET PORT A
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0202-8D 00 17 34 ( 4) STA DDRA AS OUTPUTS
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0205-A9 00 35 ( 2) LDA #$00 SET PORT B
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0207-8D 00 17 36 ( 4) STA DDRB AS INPUTS
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020A-A9 FF 37 ( 2) TIMER LDA #$FF RESET TIMER1
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020C-8D 00 17 38 ( 4) STA T1CL
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020F-8D 00 17 39 ( 4) STA T1CH
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0212-A9 40 40 ( 2) LDA #$40 FREE-RUN MODE WITHOUT
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0214-8D 00 17 41 ( 4) STA ACR ENABLING OUTPUT ON PB7
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0217-A9 C0 42 ( 2) LDA #$C0 ENABLE VIA
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0219-8D 00 17 43 ( 4) STA IER INTERRUPT
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021C-58 44 ( 2) CLI ENABLE CPU INTERRUPT
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021D- 45
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021D-A9 FF 46 ( 2) WAIT LDA #$FF READ SWITCHES,
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021F-4D 00 17 47 ( 4) EOR IRB BUT INVERT LOGIC
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0222-85 D0 48 ( 2) STA VOLUME TO AVOID KEEPING
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0224-4C 1D 02 49 ( 3) JMP WAIT VOLUME AT 100%
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0227- 50
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0227-A9 E4 51 ( 2) SETNOTE LDA #$E4
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0229-8D 00 17 52 ( 4) STA T1CL
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022C-A9 17 53 ( 2) LDA #$17
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022E-8D 00 17 54 ( 4) STA T1CH
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0231-60 55 ( 6) RTS
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0232- 56
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0232-2C 00 17 57 ( 4) INTR BIT T1CL
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0235-A5 D0 58 ( 3) LDA VOLUME
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0237-C5 D1 59 ( 3) CMP TEMP
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0239-F0 04 60 (2**) BEQ TOGGLE
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023B-85 D1 61 ( 2) STA TEMP
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023D-85 D2 62 ( 2) STA OUTPUT
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023F-A9 FF 63 ( 2) TOGGLE LDA #$FF
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0241-45 D2 64 ( 3) EOR OUTPUT
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0243-85 D2 65 ( 2) STA OUTPUT
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0245-8D 00 17 66 ( 4) STA ORA
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0248-58 67 ( 2) CLI
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0249-40 68 ( 6) RTI
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