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

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*PRIMARY ROUTINES
*FOR SLOT 4
*
ORG $9000
;ADDRESSES FOR FIRST 6522
ORB EQU $C400 ;PORT B
ORA EQU $C401 ;PORT A
DDRB EQU $C402 ;DATA DIRECTION REGISTER (A)
DDRA EQU $C403 ;DATA DIRECTION REGISTER (B)
;ADDRESSES FOR SECOND 6522
ORB2 EQU $C480 ;PORT B
ORA2 EQU $C481 ;PORT A
DDRB2 EQU $C482 ;DATA DIRECTION REGISTER (B)
DDRA2 EQU $C483 ;DATA DIRECTION REGISTER (A)
*
*ROUTINES FOR FIRST 6522
*
INIT LDA #$FF ;SET PORT A FOR OUTPUT
STA DDRA
LDA #$07 ;SET PORT B FOR OUTPUT
STA DDRB
RTS ;RETURN
*
LATCH LDA #$07 ;SEND "LATCH COMMAND"
STA ORB ;TO SOUND CHIP
LDA #$04 ;THROUGH PORT B
STA ORB
RTS ;RETURN
*
WRITE LDA #$06 ;SEND "WRITECOMMAND"
STA ORB ;TO SOUND CHIP
LDA #$04 ;THROUGHPORT B
STA ORB
RTS ;RETURN
*
RESET LDA #$00 ;SEND "RESET COMMAND"
STA ORB ;TO SOUND CHIP
LDA #$04 ;THROUGH PORT B
STA ORB
RTS ;RETURN
*
*ROUTINES FOR SECOND 6522
*
INIT2 LDA #$FF ;SET PORT A FOR OUTPUT
STA DDRA2
LDA #$07 ;SET PORT B FOR OUTPUT
STA DDRB2
RTS ;RETURN
*
LATCH2 LDA #$07 ;SEND "LATCH COMMAND"
STA ORB2 ;TO SOUND CHIP
LDA #$04 ;THROUGH PORT B
STA ORB2
RTS ;RETURN
*
WRITE2 LDA #$06 ;SEND "WRITECOMMAND"
STA ORB2 ;TO SOUND CHIP
LDA #$04 ;THROUGHPORT B
STA ORB2
RTS ;RETURN
*
STA #$00 ;SEND "RESET COMMAND"
STA ORB2 ;TO SOUND CHIP
LDA #$04 ;THROUGH PORT B
STA ORB2
RTS ;RETURN