mirror of
https://github.com/tebl/RC-Project-Board.git
synced 2024-11-29 09:50:50 +00:00
37 lines
1.2 KiB
NASM
37 lines
1.2 KiB
NASM
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.CR 6502
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.TF beep.hex,INT
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.LF beep.list
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* ----------------------------------------------------------------------
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* SAMPLE PROGRAM AS FOUND IN THE BOOK "6502 APPLICATIONS BOOK" BY RODNEY
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* ZAKS, IT IS A SOFTWARE METHOD OF CONTROLLING SOUND DURATION.ADAPTED FOR
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* THE KIM-1 WITH THE 6502 PROJECT PLATFORM BOARD / COVOX PROJECT BOARD.
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*
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DELAY .EQ $04
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VIA .EQ $1700
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IRB .EQ VIA
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ORA .EQ VIA+1
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DDRB .EQ VIA+2
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DDRA .EQ VIA+3
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.OR $0200
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.TA $0200
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START LDA #$80 LOAD A DEFAULT VALUE, START PROGRAM AT
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STA DELAY BSCSPK TO JUST USE ZP $04 AS IN THE BOOK.
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BSCSPK LDA #$FF SET PORT A
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STA DDRA AS OUTPUTS
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AGAIN LDA #$20 DEFAULT VOLUME
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STA ORA SET SPEAKER DRIVER HIGH
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JSR DLYB CALL DELAY
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LDA #$00
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STA ORA SET SPEAKER DRIVER LOW
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JSR DLYB CALL DELAY
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JMP AGAIN
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DLYB LDX DELAY LOAD DELAY VALUE INTO X
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LPXB INX INCREMENT X
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CPX #$00
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BMI LPXB LOOP TILL (X)=0
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RTS
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