; BeeperTest ; Jeff Haber ; 22 April 2017, 6:00 AM ; ; dasm DigitalNoise.asm -f3 -v0 -sDigitalNoise.sym -lDigitalNoise.lst -oDigitalNoise.bin ; My attempt to produce different frequncies without changing frequency PROCESSOR 6502 include vcs.h SEG.U VARS ORG $80 ;Start of Cartridge ; Tell DASM to start here. RAM begins at $80 HzCounter: ds 1 ; define the segment for code SEG CODE ; 2K ROM starts at $F800, 4K ROM starts at $F000 ORG $F800 InitSystem: sei ; Set Interrupt cld ; Clear the decimal bit. ldx #$FF ; Start at the top of the stack txs ; Transfer to the stack lda #0 ClearMem: sta 0,X ; Store zero at (0+X) dex ; Do all of RAM bne ClearMem ; Repeat if we are not down to zero Beeper: lda #$0F ; 2 sta AUDV0 ; 3 ldy HzCounter WaveHigh: nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop dey bne WaveHigh Interval: lda #$00 ; 2 sta AUDV0 ; 3 ldy HzCounter WaveLow: nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop nop dey bne WaveLow inc HzCounter jmp Beeper ; End of Cartridge ORG $FFFA ; set address to 6507 Interrupt Vectors .WORD InitSystem ; NMI .WORD InitSystem ; RESET .WORD InitSystem ; IRQ