apple2_mockingboard/docs/mockingboard_laser_n_bomb_assy.txt
Michaelangel007 24a1b679b7 Add docs
2017-04-15 11:09:24 -07:00

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