120 lines
3.1 KiB
ArmAsm
120 lines
3.1 KiB
ArmAsm
; Mockingboad programming:
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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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; TODO: how to auto-detect?
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; References used:
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; http://macgui.com/usenet/?group=2&id=8366
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; 6522 Data Sheet
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; AY-3-8910 Data Sheet
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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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; left speaker
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MOCK_6522_ORB1 = $C400 ; 6522 #1 port b data
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MOCK_6522_ORA1 = $C401 ; 6522 #1 port a data
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MOCK_6522_DDRB1 = $C402 ; 6522 #1 data direction port B
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MOCK_6522_DDRA1 = $C403 ; 6522 #1 data direction port A
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MOCK_6522_T1CL = $C404 ; 6522 #1 t1 low order latches
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MOCK_6522_T1CH = $C405 ; 6522 #1 t1 high order counter
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MOCK_6522_T1LL = $C406 ; 6522 #1 t1 low order latches
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MOCK_6522_T1LH = $C407 ; 6522 #1 t1 high order latches
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MOCK_6522_T2CL = $C408 ; 6522 #1 t2 low order latches
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MOCK_6522_T2CH = $C409 ; 6522 #1 t2 high order counters
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MOCK_6522_SR = $C40A ; 6522 #1 shift register
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MOCK_6522_ACR = $C40B ; 6522 #1 auxilliary control register
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MOCK_6522_PCR = $C40C ; 6522 #1 peripheral control register
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MOCK_6522_IFR = $C40D ; 6522 #1 interrupt flag register
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MOCK_6522_IER = $C40E ; 6522 #1 interrupt enable register
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MOCK_6522_ORANH = $C40F ; 6522 #1 port a data no handshake
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; right speaker
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MOCK_6522_ORB2 = $C480 ; 6522 #2 port b data
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MOCK_6522_ORA2 = $C481 ; 6522 #2 port a data
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MOCK_6522_DDRB2 = $C482 ; 6522 #2 data direction port B
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MOCK_6522_DDRA2 = $C483 ; 6522 #2 data direction port A
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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 = $0 ; 0 0 0
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MOCK_AY_INACTIVE = $4 ; 1 0 0
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MOCK_AY_READ = $5 ; 1 0 1
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MOCK_AY_WRITE = $6 ; 1 1 0
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MOCK_AY_LATCH_ADDR = $7 ; 1 1 1
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;========================
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;========================
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; Mockingboard Init
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;========================
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;========================
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; Left channel only
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mockingboard_init:
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;=========================
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; Initialize the 6522s
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; Reset Left AY-3-8910
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;===========================
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; ldx #$FF
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; stx MOCK_6522_DDRB1
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; stx MOCK_6522_DDRA1
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; inx ; #MOCK_AY_RESET $0
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; stx MOCK_6522_ORB1
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; ldx #MOCK_AY_INACTIVE ; $4
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; stx MOCK_6522_ORB1
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; sei ; disable interrupts, is this necessary?
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;=========================
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; Setup Interrupt Handler
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;=========================
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; NOTE: we don't support IIc as it's a hack
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; traditionally Mockingboard on IIc was rare
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;========================
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; set up interrupt
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; Vector address goes to 0x3fe/0x3ff
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; can save 10 bytes if we load in memory so this
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; is in the right place automatically
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lda #<interrupt_handler ; 2
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sta $03fe ; 3
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lda #>interrupt_handler ; 2
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sta $03ff ; 3
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;=========
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; 10
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;=========================
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; Initialize the 6522s
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; Reset Left AY-3-8910
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;===========================
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; entries=10
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; 14 + 2*entries = 34 bytes
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; assume Y=0 on entry?
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ldy #0 ; 2
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init_it_loop:
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lda init_values,Y ; 3
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ldx init_addresses,Y ; 3
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bmi doneit ; 2
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iny ; 1
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sta $c400,X ; 3
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bne init_it_loop ; 2
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doneit:
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