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mockingboard: work out a bit more how the 6522 works
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Vince Weaver
parent
be03724db6
commit
54690d0f94
@ -1850,4 +1850,5 @@ ksptheme:
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.byte $EE,$00,$3E,$01,$00,$00,$00,$38,$0B,$0B,$00,$00,$00,$FF ; 01821
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.byte $EE,$00,$3E,$01,$00,$00,$00,$38,$04,$04,$00,$00,$00,$FF ; 01822
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.byte $EE,$00,$3E,$01,$00,$00,$00,$38,$00,$00,$00,$00,$00,$FF ; 01823
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.byte $FF,$FF
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; Total size = 21888 bytes
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@ -1,51 +1,10 @@
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; http://macgui.com/usenet/?group=2&id=8366
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; Mockingboad programming:
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; + Has two 6522 I/O chips
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; + Has two 6522 I/O chips connected to two AY-3-8910 chips
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; + Optionally has some speech chips controlled via the outport on the AY
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; + Often in slot 4
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; $C400 ORB1 function to perform, OUT 1
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; $C401 ORA1 data, OUT 1
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; $C402 DDRB1 data direction, OUT 1
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; $C403 DDRA1 data direction, OUT 1
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; $C480 ORB2 function to perform, OUT 2
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; $C481 ORA2 data, OUT 2
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; $C482 DDRB2 data direction, OUT 2
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; $C483 DDRA2 data direction, OUT 2
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; To Initialize the 6522s: Store $FF at the DDRxx addresses
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; Your program gets access to a PSG via the 6522 by using a few basic
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; Function codes which set the PSG's I/O control lines:
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;
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; Set Inactive = $04 Set PSG Reg# = $07 Write Data = $06 Reset = $00
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;
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; To Write to a PSG register: Tell the PSG which Register you wish to access
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; (i.e. Set the "current register" #) and Write the data. This is easiest to
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; do with subroutines to handle the basic Functions.
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;
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; Example Subroutines (for Output Channel 1):
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;
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; Set Reg # 1000: A9 07 8D 00 C4 A9 04 8D 00 C4 60
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; Write Data 100B: A9 06 8D 00 C4 A9 04 8D 00 C4 60
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; Notice that each Function sub ends by setting the PSG control lines to
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; Inactive.
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; Similarly, to do a Reset (set all PSG regs to zero) ...
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; Reset 1016: A9 00 8D 00 C4 A9 04 8D 00 C4 60
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; To put the value $55 in PSG Register 02 (Channel B Freq. fine) ....
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; 1080: A9 02 put Reg# in A
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; 1082: 8D 01 C4 store A at the Data address ORA1
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; 1085: 20 00 10 JSR to Set Reg# (sets "current register" to Register
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; 2)
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; 1088: A9 55 put the value $55 in A
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; 108A: 8D 01 C4 store A at the Data address ORA1
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; 108D: 20 0B 10 JSR to Write Data ($55 goes into PSG Register 2)
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; 1090: 60 Exit from subroutine
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; TODO: how to auto-detect?
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.include "zp.inc"
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@ -55,7 +14,181 @@
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jsr HOME
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jsr TEXT
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lda #0
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sta DRAW_PAGE
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sta CH
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sta CV
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lda #<mocking_message
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sta OUTL
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lda #>mocking_message
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sta OUTH
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jsr move_and_print
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;============================
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; Init the Mockingboard
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;============================
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jsr mockingboard_init
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jsr reset_ay_left
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jsr reset_ay_right
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;===========================
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; load pointer to the music
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;===========================
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lda #<ksptheme
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sta INL
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lda #>ksptheme
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sta OUTL
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play_loop:
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delay_a_bit:
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lda #86
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jsr WAIT ; delay 1/2(26+27A+5A^2) us
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; 50Hz = 20ms = 20000us
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; 40000 = 26+27A+5A^2
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; 5a^2+27a-39974 = 0
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; A = 86.75
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done_play:
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lda #0
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sta CH
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lda #2
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sta CV
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lda #<done_message
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sta OUTL
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lda #>done_message
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sta OUTH
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jsr move_and_print
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forever_loop:
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jmp forever_loop
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; left speaker
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MOCK_6522_ORB1 EQU $C400 ; function to perform, OUT 1
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MOCK_6522_ORA1 EQU $C401 ; data, OUT 1
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MOCK_6522_DDRB1 EQU $C402 ; data direction, OUT 1
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MOCK_6522_DDRA1 EQU $C403 ; data direction, OUT 1
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; right speaker
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MOCK_6522_ORB2 EQU $C480 ; function to perform, OUT 2
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MOCK_6522_ORA2 EQU $C481 ; data, OUT 2
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MOCK_6522_DDRB2 EQU $C482 ; data direction, OUT 2
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MOCK_6522_DDRA2 EQU $C483 ; data direction, OUT 2
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; AY-3-8910 commands on port B
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; RESET BDIR BC1
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MOCK_AY_RESET EQU $0 ; 0 0 0
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MOCK_AY_INACTIVE EQU $4 ; 1 0 0
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MOCK_AY_READ EQU $5 ; 1 0 1
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MOCK_AY_WRITE EQU $6 ; 1 1 0
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MOCK_AY_LATCH_ADDR EQU $7 ; 1 1 1
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;========================
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; Mockingboard card
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; Essentially two 6522s hooked to the Apple II bus
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; Connected to AY-3-8910 chips
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; PA0-PA7 on 6522 connected to DA0-DA7 on AY
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; PB0 on 6522 connected to BC1
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; PB1 on 6522 connected to BDIR
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; PB2 on 6522 connected to RESET
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;========================
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; Mockingboard Init
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;========================
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mockingboard_init:
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; Initialize the 6522s
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; set the data direction for all pins of PortA/PortB to be output
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lda #$ff ; all output (1)
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sta MOCK_6522_DDRB1
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sta MOCK_6522_DDRA1
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sta MOCK_6522_DDRB2
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sta MOCK_6522_DDRA2
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rts
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;======================
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; Reset Left AY-3-8910
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;======================
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reset_ay_left:
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lda #MOCK_AY_RESET
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sta MOCK_6522_ORB1
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lda #MOCK_AY_INACTIVE
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sta MOCK_6522_ORB1
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rts
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;======================
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; Reset Right AY-3-8910
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;======================
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reset_ay_right:
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lda #MOCK_AY_RESET
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sta MOCK_6522_ORB2
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lda #MOCK_AY_INACTIVE
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sta MOCK_6522_ORB2
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rts
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; Write sequence
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; Inactive -> Latch Address -> Inactive -> Write Data -> Inactive
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;=======================
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; Write Right AY-3-8910
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;=======================
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; register in X
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; value in Y
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write_right_ay:
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; address
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stx MOCK_6522_ORA1 ; put address on PA
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lda #MOCK_AY_LATCH_ADDR ; latch_address on PB
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sta MOCK_6522_ORB1
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lda #MOCK_AY_INACTIVE ; go inactive
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sta MOCK_6522_ORB1
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; value
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sty MOCK_6522_ORA1 ; put value on PA
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lda #MOCK_AY_WRITE ; write on PB
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sta MOCK_6522_ORB1
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lda #MOCK_AY_INACTIVE ; go inactive
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sta MOCK_6522_ORB1
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rts
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;=======================
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; Write Left AY-3-8910
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;=======================
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; register in X
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; value in Y
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write_left_ay:
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; address
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stx MOCK_6522_ORA2 ; put address on PA
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lda #MOCK_AY_LATCH_ADDR ; latch_address on PB
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sta MOCK_6522_ORB2
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lda #MOCK_AY_INACTIVE ; go inactive
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sta MOCK_6522_ORB2
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; value
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sty MOCK_6522_ORA2 ; put value on PA
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lda #MOCK_AY_WRITE ; write on PB
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sta MOCK_6522_ORB2
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lda #MOCK_AY_INACTIVE ; go inactive
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sta MOCK_6522_ORB2
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rts
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;routines
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.include "../asm_routines/gr_offsets.s"
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.include "../asm_routines/text_print.s"
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; music
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.include "ksptheme_uncompressed.inc"
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mocking_message: .asciiz "ASSUMING MOCKINGBOARD IN SLOT #4"
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done_message: .asciiz "DONE PLAYING"
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