403 lines
9.1 KiB
ArmAsm
403 lines
9.1 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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; 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 = $7 ; 1 1 1
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;========================
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; Mockingboard Init
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;========================
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; Initialize the 6522s
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; set the data direction for all pins of PortA/PortB to be output
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mockingboard_init:
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lda #$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_both:
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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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;======================
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; Reset Right AY-3-8910
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;======================
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;reset_ay_right:
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;could be merged with both
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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/Left to save value AY-3-8910
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;=========================================
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; register in X
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; value in MB_VALUE
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write_ay_both:
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; address
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stx MOCK_6522_ORA1 ; put address on PA1 ; 4
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stx MOCK_6522_ORA2 ; put address on PA2 ; 4
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lda #MOCK_AY_LATCH_ADDR ; latch_address on PB1 ; 2
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sta MOCK_6522_ORB1 ; latch_address on PB1 ; 4
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sta MOCK_6522_ORB2 ; latch_address on PB2 ; 4
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ldy #MOCK_AY_INACTIVE ; go inactive ; 2
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sty MOCK_6522_ORB1 ; 4
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sty MOCK_6522_ORB2 ; 4
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;===========
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; 28
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; value
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lda MB_VALUE ; 3
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sta MOCK_6522_ORA1 ; put value on PA1 ; 4
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sta MOCK_6522_ORA2 ; put value on PA2 ; 4
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lda #MOCK_AY_WRITE ; ; 2
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sta MOCK_6522_ORB1 ; write on PB1 ; 4
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sta MOCK_6522_ORB2 ; write on PB2 ; 4
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sty MOCK_6522_ORB1 ; 4
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sty MOCK_6522_ORB2 ; 4
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;===========
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; 29
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rts ; 6
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;===========
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; 63
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write_ay_both_end:
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.assert >write_ay_both = >write_ay_both_end, error, "write_ay_both crosses page"
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;=======================================
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; clear ay -- clear all 14 AY registers
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; should silence the card
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;=======================================
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; 7+(74*14)+5=1048
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clear_ay_both:
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ldx #13 ; 2
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lda #0 ; 2
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sta MB_VALUE ; 3
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clear_ay_left_loop:
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jsr write_ay_both ; 6+63
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dex ; 2
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bpl clear_ay_left_loop ; 3
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; -1
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rts ; 6
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clear_ay_end:
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.assert >clear_ay_both = >clear_ay_end, error, "clea_ay_both crosses page"
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;=======================================
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; Detect a Mockingboard card
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;=======================================
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; Based on code from the French Touch "Pure Noise" Demo
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; Attempts to time an instruction sequence with a 6522
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;
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; If found, puts in bMB
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; MB_ADDRL:MB_ADDRH has address of Mockingboard
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; returns X=0 if not found, X=1 if found
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mockingboard_detect:
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lda #0
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sta MB_ADDRL
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mb_detect_loop: ; self-modifying
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lda #$07 ; we start in slot 7 ($C7) and go down to 0 ($C0)
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ora #$C0 ; make it start with C
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sta MB_ADDRH
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ldy #04 ; $CX04
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ldx #02 ; 2 tries?
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mb_check_cycle_loop:
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lda (MB_ADDRL),Y ; timer 6522 (Low Order Counter)
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; count down
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sta PT3_TEMP ; 3 cycles
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lda (MB_ADDRL),Y ; + 5 cycles = 8 cycles
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; between the two accesses to the timer
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sec
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sbc PT3_TEMP ; subtract to see if we had 8 cycles
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cmp #$f8 ; -8
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bne mb_not_in_this_slot
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dex ; decrement, try one more time
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bne mb_check_cycle_loop ; loop detection
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inx ; Mockingboard found (X=1)
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done_mb_detect:
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;stx bMB ; store result to bMB
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rts ; return
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mb_not_in_this_slot:
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dec mb_detect_loop+1 ; decrement the "slot" (self_modify)
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bne mb_detect_loop ; loop down to one
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ldx #00
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beq done_mb_detect
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;alternative MB detection from Nox Archaist
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; lda #$04
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; sta MB_ADDRL
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; ldx #$c7
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;
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;find_mb:
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; stx MB_ADDRH
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;
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; ;detect sound I
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;
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; sec
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; ldy #$00
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; lda (MB_ADDRL), y
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; sbc (MB_ADDRL), y
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; cmp #$05
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; beq found_mb
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; dex
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; cpx #$c0
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; bne find_mb
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; ldx #$00 ;no mockingboard found
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; rts
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;
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;found_mb:
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; ldx #$01 ;mockingboard found
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; rts
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;
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; ;optionally detect sound II
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;
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; sec
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; ldy #$80
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; lda (MB_ADDRL), y
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; sbc (MB_ADDRL), y
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; cmp #$05
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; beq found_mb
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;=======================================
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; Detect a Mockingboard card in Slot4
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;=======================================
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; Based on code from the French Touch "Pure Noise" Demo
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; Attempts to time an instruction sequence with a 6522
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;
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; MB_ADDRL:MB_ADDRH has address of Mockingboard
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; returns X=0 if not found, X=1 if found
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mockingboard_detect_slot4:
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lda #0
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sta MB_ADDRL
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mb4_detect_loop: ; self-modifying
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lda #$04 ; we're only looking in Slot 4
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ora #$C0 ; make it start with C
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sta MB_ADDRH
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ldy #04 ; $CX04
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ldx #02 ; 2 tries?
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mb4_check_cycle_loop:
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lda (MB_ADDRL),Y ; timer 6522 (Low Order Counter)
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; count down
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sta PT3_TEMP ; 3 cycles
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lda (MB_ADDRL),Y ; + 5 cycles = 8 cycles
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; between the two accesses to the timer
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sec
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sbc PT3_TEMP ; subtract to see if we had 8 cycles
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cmp #$f8 ; -8
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bne mb4_not_in_this_slot
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dex ; decrement, try one more time
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bne mb4_check_cycle_loop ; loop detection
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inx ; Mockingboard found (X=1)
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done_mb4_detect:
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rts ; return
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mb4_not_in_this_slot:
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ldx #00
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beq done_mb4_detect
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;=============================
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; Setup
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;=============================
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pt3_setup_interrupt:
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;===========================
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; Check for Apple IIc
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;===========================
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; it does interrupts differently
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lda $FBB3 ; IIe and newer is $06
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cmp #6
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beq apple_iie_or_newer
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jmp done_apple_detect
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apple_iie_or_newer:
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lda $FBC0 ; 0 on a IIc
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bne done_apple_detect
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apple_iic:
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; activate IIc mockingboard?
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; this might only be necessary to allow detection
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; I get the impression the Mockingboard 4c activates
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; when you access any of the 6522 ports in Slot 4
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lda #$ff
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sta $C403
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sta $C404
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; bypass the firmware interrupt handler
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; should we do this on IIe too? probably faster
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done_apple_detect:
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sei ; disable interrupts
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lda $c08b ; disable ROM (enable language card)
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lda $c08b
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lda #<interrupt_handler
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sta $fffe
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lda #>interrupt_handler
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sta $ffff
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lda #$EA ; nop out the "lda $45" in the irq hand
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sta interrupt_smc
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sta interrupt_smc+1
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;=========================
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; Setup Interrupt Handler
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;=========================
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; Vector address goes to 0x3fe/0x3ff
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; FIXME: should chain any existing handler
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lda #<interrupt_handler
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sta $03fe
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lda #>interrupt_handler
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sta $03ff
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;============================
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; Enable 60Hz clock on 6522
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;============================
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; yes this is horrible for PT3 files
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; but in our case we are matching the screen refresh
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sei ; disable interrupts just in case
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lda #$40 ; Continuous interrupts, don't touch PB7
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sta $C40B ; ACR register
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lda #$7F ; clear all interrupt flags
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sta $C40E ; IER register (interrupt enable)
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lda #$C0
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sta $C40D ; IFR: 1100, enable interrupt on timer one oflow
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sta $C40E ; IER: 1100, enable timer one interrupt
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lda #$1A
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sta $C404 ; write into low-order latch
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lda #$41
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sta $C405 ; write into high-order latch,
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; load both values into counter
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; clear interrupt and start counting
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; 9c40 / 1e6 = .040s, 25Hz
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; 4fe7 / 1e6 = .020s, 50Hz
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; 411a / 1e6 = .016s, 60Hz
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rts
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;==================================
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; Print mockingboard detect message
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;==================================
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; note: on IIc must do this before enabling interrupt
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; as we disable ROM (COUT won't work?)
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print_mockingboard_detect:
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; print detection message
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; ldy #0
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;print_mocking_message:
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; lda mocking_message,Y ; load loading message
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; beq done_mocking_message
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; ora #$80
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; jsr COUT
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; iny
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; jmp print_mocking_message
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;done_mocking_message:
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; jsr CROUT1
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rts
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print_mocking_notfound:
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; ldy #0
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;print_not_message:
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; lda not_message,Y ; load loading message
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; beq print_not_message_done
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; ora #$80
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; jsr COUT
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; iny
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; jmp print_not_message
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;print_not_message_done:
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rts
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print_mocking_found:
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; ldy #0
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;print_found_message:
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; lda found_message,Y ; load loading message
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; beq done_found_message
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; ora #$80
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; jsr COUT
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; iny
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; jmp print_found_message
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done_found_message:
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rts
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;=========
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; strings
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;=========
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;mocking_message: .asciiz "LOOKING FOR MOCKINGBOARD IN SLOT #4"
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;not_message: .byte "NOT "
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;found_message: .asciiz "FOUND"
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