Apple2-IO-RPi/Apple2/FileAccessFirmware.asm
2021-10-06 20:40:08 -04:00

155 lines
2.5 KiB
NASM

;ProDOS Zero Page
Command = $42 ;ProDOS Command
Unit = $43 ;ProDOS unit (SDDD0000)
BufferLo = $44
BufferHi = $45
BlockLo = $46
BlockHi = $47
; ProDOS Error Codes
IOError = $27
NoDevice = $28
WriteProtect = $2B
InputByte = $c08e+SLOT*$10
OutputByte = $c08d+SLOT*$10
InputFlags = $c08b+SLOT*$10
OutputFlags = $c087+SLOT*$10
ReadBlockCommand = $01
WriteBlockCommand = $02
GetTimeCommand = $03
ChangeDriveCommand = $04
ExecCommand = $05
LoadFileCommand = $06
SaveFileCommand = $07
MenuCommand = $08
InputString = $fd67
Monitor = $ff59
.org SLOT*$100 + $C000
;ID bytes for booting and drive detection
cpx #$20 ;ID bytes for ProDOS and the
cpx #$00 ; Apple Autostart ROM
cpx #$03 ;
ldx #SLOT*$10
stx $2b
stx Unit
;force EPROM to second page on boot
lda #$3f ;set all flags high and page 3 of EPROM for menu
PageJump:
sta OutputFlags
jmp Start ;this jump is only called if coming in from PageJump with A=$2f
;entry points for ProDOS
DriverEntry:
lda #$0f ;set all flags high and page 0 of EPROM
sta OutputFlags
Start:
lda #$a4
sta $33
GetFilename:
jsr InputString
LoadFile:
lda #$00
sta BufferLo
lda #$20
sta BufferHi
lda #$06 ; send command 6 = load
jsr SendByte
ldy #$00
sendFilename:
lda $0200,y
cmp #$8d
beq sendNullTerminator
and #$7f
jsr SendByte
iny
bne sendFilename
sendNullTerminator:
lda #$00
jsr SendByte
jsr GetByte
sta BlockLo ; not really a block, just using the memory space
jsr GetByte
sta BlockHi
NextPage:
lda BlockHi
beq ReadFinalPage
ldy #$00
NextByte:
jsr GetByte
sta (BufferLo),y
iny
bne NextByte
inc BufferHi
dec BlockHi
bne NextPage
ReadFinalPage:
lda BlockLo
beq ExitToMonitor
ldy #$00
NextByteFinal:
jsr GetByte
sta (BufferLo),y
iny
cpy BlockLo
bne NextByteFinal
ExitToMonitor:
jsr Monitor
SendByte:
pha
waitWrite:
lda InputFlags
rol
rol
bcs waitWrite
pla
sta OutputByte
lda #$2e ; set bit 0 low to indicate write started
sta OutputFlags
finishWrite:
lda InputFlags
rol
rol
bcc finishWrite
lda #$2f
sta OutputFlags
rts
GetByte:
lda #$2d ;set read flag low
sta OutputFlags
waitRead:
lda InputFlags
rol
bcs waitRead
lda InputByte
pha
lda #$2f ;set all flags high
sta OutputFlags
finishRead:
lda InputFlags
rol
bcc finishRead
pla
end:
rts
.repeat 251-<end
.byte 0
.endrepeat
.byte 0,0 ;0000 blocks = check status
.byte 7 ;bit set(0=status 1=read 2=write) unset(3=format, 4/5=number of volumes, 6=interruptable, 7=removable)
.byte DriverEntry&$00FF ;low byte of entry