108 lines
1.2 KiB
Plaintext
108 lines
1.2 KiB
Plaintext
;PROCESSOR LOOP
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;FOR LASER AND BOMB
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;SOUND EFFECT
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*
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ORG $8F00
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;FOR FIRST 6522
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*
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PTR EQU $08 ;DATA POINTE
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TONE EQU $0A ;TONAL VALUE
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TIME EQU $0B ;TIME VALUE FOR DELAY
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BASE EQU $C400 ;CARD ADDRESS
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ORA EQU BASE+1 ;PORT A
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TAR EQU $8000 ; TABLE ACCESS ROUTINE
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LATCH EQU $900B ;LATCH SUBROUTINE
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WRITE EQU $9016 ;WRITE SUBROUTINE
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RESET EQU $9021 ;RESET SUBROUTINE
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WAIT EQU $FCAB ;WAIT SUBROUTINE
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*
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*
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LASER LDA #$00 ;LOAD HIGHEST
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STA TONE ;FREQUENCY VALUE
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LDA #$0F ;LOAD SHORT
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STA TIME ;TIME DELAY
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JMP START ;AND START
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BOMB LDA #$30 ;LOAD MIDDLE
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STA TONE ;FREQUENCY VALUE
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LDA #$40 ;LOAD LONGER
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STA TIME ;TIME DELAY
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START LDA #$90 ;SET TABLE ADDRESS
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STA PTR
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LDA #$81
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STA PTR+1
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JSR TAR ;TRANSFER DATA
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LDA #$00 ;LATCH FIRST REGISTER
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STA ORA ;ADDRESS
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JSR LATCH
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LOOP LDA TONE ;GET TONE VALUE
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STA ORA ;STORE IN REGISTER
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JSR WRITE
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LDA TIME ;GET TIME VALUE
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JSR WAIT ;AND DELAY
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INC TONE ;INCREMENT TONE VALUE
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LDA #$FF ;END OF INCREASE?
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CMP TONE
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BEQ DONE ;YES,EXIT
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JMP LOOP ;NO, START AGAIN
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DONE LDA TIME ;GET TIME VALUE
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JSR WAIT ;DELAY
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LDA #$00 ;RESTORE ORIGINAL
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STA TONE ;TONE VALUE
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JSR RESET ;CLEAR SOUND CHIP
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RTS ;REGISTERS AND RETURN
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