dos33fsprogs/pt3_lib/pt3_lib_mockingboard.s

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; Mockingboad programming:
; + Has two 6522 I/O chips connected to two AY-3-8910 chips
; + Optionally has some speech chips controlled via the outport on the AY
; + Often in slot 4
; TODO: how to auto-detect?
; References used:
; http://macgui.com/usenet/?group=2&id=8366
; 6522 Data Sheet
; AY-3-8910 Data Sheet
;========================
; Mockingboard card
; Essentially two 6522s hooked to the Apple II bus
; Connected to AY-3-8910 chips
; PA0-PA7 on 6522 connected to DA0-DA7 on AY
; PB0 on 6522 connected to BC1
; PB1 on 6522 connected to BDIR
; PB2 on 6522 connected to RESET
; left speaker
MOCK_6522_ORB1 = $C400 ; 6522 #1 port b data
MOCK_6522_ORA1 = $C401 ; 6522 #1 port a data
MOCK_6522_DDRB1 = $C402 ; 6522 #1 data direction port B
MOCK_6522_DDRA1 = $C403 ; 6522 #1 data direction port A
; right speaker
MOCK_6522_ORB2 = $C480 ; 6522 #2 port b data
MOCK_6522_ORA2 = $C481 ; 6522 #2 port a data
MOCK_6522_DDRB2 = $C482 ; 6522 #2 data direction port B
MOCK_6522_DDRA2 = $C483 ; 6522 #2 data direction port A
; AY-3-8910 commands on port B
; RESET BDIR BC1
MOCK_AY_RESET = $0 ; 0 0 0
MOCK_AY_INACTIVE = $4 ; 1 0 0
MOCK_AY_READ = $5 ; 1 0 1
MOCK_AY_WRITE = $6 ; 1 1 0
MOCK_AY_LATCH_ADDR = $7 ; 1 1 1
;========================
; Mockingboard Init
;========================
; Initialize the 6522s
; set the data direction for all pins of PortA/PortB to be output
mockingboard_init:
lda #$ff ; all output (1)
sta MOCK_6522_DDRB1
sta MOCK_6522_DDRA1
sta MOCK_6522_DDRB2
sta MOCK_6522_DDRA2
rts
;======================
; Reset Left AY-3-8910
;======================
reset_ay_both:
lda #MOCK_AY_RESET
sta MOCK_6522_ORB1
lda #MOCK_AY_INACTIVE
sta MOCK_6522_ORB1
;======================
; Reset Right AY-3-8910
;======================
;reset_ay_right:
;could be merged with both
lda #MOCK_AY_RESET
sta MOCK_6522_ORB2
lda #MOCK_AY_INACTIVE
sta MOCK_6522_ORB2
rts
; Write sequence
; Inactive -> Latch Address -> Inactive -> Write Data -> Inactive
;=========================================
; Write Right/Left to save value AY-3-8910
;=========================================
; register in X
; value in MB_VALUE
write_ay_both:
; address
stx MOCK_6522_ORA1 ; put address on PA1 ; 3
stx MOCK_6522_ORA2 ; put address on PA2 ; 3
lda #MOCK_AY_LATCH_ADDR ; latch_address on PB1 ; 2
sta MOCK_6522_ORB1 ; latch_address on PB1 ; 3
sta MOCK_6522_ORB2 ; latch_address on PB2 ; 3
ldy #MOCK_AY_INACTIVE ; go inactive ; 2
sty MOCK_6522_ORB1 ; 3
sty MOCK_6522_ORB2 ; 3
; value
lda MB_VALUE ; 3
sta MOCK_6522_ORA1 ; put value on PA1 ; 3
sta MOCK_6522_ORA2 ; put value on PA2 ; 3
lda #MOCK_AY_WRITE ; ; 2
sta MOCK_6522_ORB1 ; write on PB1 ; 3
sta MOCK_6522_ORB2 ; write on PB2 ; 3
sty MOCK_6522_ORB1 ; 3
sty MOCK_6522_ORB2 ; 3
rts ; 6
;===========
; 51
;=======================================
; clear ay -- clear all 14 AY registers
; should silence the card
;=======================================
clear_ay_both:
ldx #14
lda #0
sta MB_VALUE
clear_ay_left_loop:
jsr write_ay_both
dex
bpl clear_ay_left_loop
rts
;=======================================
; Detect a Mockingboard card
;=======================================
; Based on code from the French Touch "Pure Noise" Demo
; Attempts to time an instruction sequence with a 6522
;
; If found, puts in bMB
; MB_ADDRL:MB_ADDRH has address of Mockingboard
; returns X=0 if not found, X=1 if found
mockingboard_detect:
lda #0
sta MB_ADDRL
mb_detect_loop: ; self-modifying
lda #$07 ; we start in slot 7 ($C7) and go down to 0 ($C0)
ora #$C0 ; make it start with C
sta MB_ADDRH
ldy #04 ; $CX04
ldx #02 ; 2 tries?
mb_check_cycle_loop:
lda (MB_ADDRL),Y ; timer 6522 (Low Order Counter)
; count down
sta PT3_TEMP ; 3 cycles
lda (MB_ADDRL),Y ; + 5 cycles = 8 cycles
; between the two accesses to the timer
sec
sbc PT3_TEMP ; subtract to see if we had 8 cycles
cmp #$f8 ; -8
bne mb_not_in_this_slot
dex ; decrement, try one more time
bne mb_check_cycle_loop ; loop detection
inx ; Mockingboard found (X=1)
done_mb_detect:
;stx bMB ; store result to bMB
rts ; return
mb_not_in_this_slot:
dec mb_detect_loop+1 ; decrement the "slot" (self_modify)
bne mb_detect_loop ; loop down to one
ldx #00
beq done_mb_detect
;alternative MB detection from Nox Archaist
; lda #$04
; sta MB_ADDRL
; ldx #$c7
;
;find_mb:
; stx MB_ADDRH
;
; ;detect sound I
;
; sec
; ldy #$00
; lda (MB_ADDRL), y
; sbc (MB_ADDRL), y
; cmp #$05
; beq found_mb
; dex
; cpx #$c0
; bne find_mb
; ldx #$00 ;no mockingboard found
; rts
;
;found_mb:
; ldx #$01 ;mockingboard found
; rts
;
; ;optionally detect sound II
;
; sec
; ldy #$80
; lda (MB_ADDRL), y
; sbc (MB_ADDRL), y
; cmp #$05
; beq found_mb
;=======================================
; Detect a Mockingboard card in Slot4
;=======================================
; Based on code from the French Touch "Pure Noise" Demo
; Attempts to time an instruction sequence with a 6522
;
; MB_ADDRL:MB_ADDRH has address of Mockingboard
; returns X=0 if not found, X=1 if found
mockingboard_detect_slot4:
lda #0
sta MB_ADDRL
mb4_detect_loop: ; self-modifying
lda #$04 ; we're only looking in Slot 4
ora #$C0 ; make it start with C
sta MB_ADDRH
ldy #04 ; $CX04
ldx #02 ; 2 tries?
mb4_check_cycle_loop:
lda (MB_ADDRL),Y ; timer 6522 (Low Order Counter)
; count down
sta PT3_TEMP ; 3 cycles
lda (MB_ADDRL),Y ; + 5 cycles = 8 cycles
; between the two accesses to the timer
sec
sbc PT3_TEMP ; subtract to see if we had 8 cycles
cmp #$f8 ; -8
bne mb4_not_in_this_slot
dex ; decrement, try one more time
bne mb4_check_cycle_loop ; loop detection
inx ; Mockingboard found (X=1)
done_mb4_detect:
rts ; return
mb4_not_in_this_slot:
ldx #00
beq done_mb4_detect
;=============================
; Setup
;=============================
pt3_setup_interrupt:
;===========================
; Check for Apple IIc
;===========================
; it does interrupts differently
lda $FBB3 ; IIe and newer is $06
cmp #6
beq apple_iie_or_newer
jmp done_apple_detect
apple_iie_or_newer:
lda $FBC0 ; 0 on a IIc
bne done_apple_detect
apple_iic:
; activate IIc mockingboard?
; this might only be necessary to allow detection
; I get the impression the Mockingboard 4c activates
; when you access any of the 6522 ports in Slot 4
lda #$ff
sta $C403
sta $C404
; bypass the firmware interrupt handler
; should we do this on IIe too? probably faster
sei ; disable interrupts
lda $c08b ; disable ROM (enable language card)
lda $c08b
lda #<interrupt_handler
sta $fffe
lda #>interrupt_handler
sta $ffff
lda #$EA ; nop out the "lda $45" in the irq hand
sta interrupt_smc
sta interrupt_smc+1
done_apple_detect:
;=========================
; Setup Interrupt Handler
;=========================
; Vector address goes to 0x3fe/0x3ff
; FIXME: should chain any existing handler
lda #<interrupt_handler
sta $03fe
lda #>interrupt_handler
sta $03ff
;============================
; Enable 50Hz clock on 6522
;============================
sei ; disable interrupts just in case
lda #$40 ; Continuous interrupts, don't touch PB7
sta $C40B ; ACR register
lda #$7F ; clear all interrupt flags
sta $C40E ; IER register (interrupt enable)
lda #$C0
sta $C40D ; IFR: 1100, enable interrupt on timer one oflow
sta $C40E ; IER: 1100, enable timer one interrupt
lda #$E7
sta $C404 ; write into low-order latch
lda #$4f
sta $C405 ; write into high-order latch,
; load both values into counter
; clear interrupt and start counting
; 4fe7 / 1e6 = .020s, 50Hz
rts
;==================================
; Print mockingboard detect message
;==================================
; note: on IIc must do this before enabling interrupt
; as we disable ROM (COUT won't work?)
print_mockingboard_detect:
; print detection message
ldy #0
print_mocking_message:
lda mocking_message,Y ; load loading message
beq done_mocking_message
ora #$80
jsr COUT
iny
jmp print_mocking_message
done_mocking_message:
jsr CROUT1
rts
print_mocking_notfound:
ldy #0
print_not_message:
lda not_message,Y ; load loading message
beq print_not_message_done
ora #$80
jsr COUT
iny
jmp print_not_message
print_not_message_done:
rts
print_mocking_found:
ldy #0
print_found_message:
lda found_message,Y ; load loading message
beq done_found_message
ora #$80
jsr COUT
iny
jmp print_found_message
done_found_message:
rts
;=========
; strings
;=========
mocking_message: .asciiz "LOOKING FOR MOCKINGBOARD IN SLOT #4"
not_message: .byte "NOT "
found_message: .asciiz "FOUND"