Apple2-IO-RPi/Apple2/MenuFirmware.asm
2021-07-17 10:13:25 -04:00

163 lines
2.7 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
Wait = $fca8
PrintChar = $fded
Home = $fc58
ReadChar = $fd0c
.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 1 of EPROMi
PageJump:
sta OutputFlags
jmp Start
;entry points for ProDOS
DriverEntry:
lda #$0f ;set all flags high and page 0 of EPROM
sta OutputFlags
;since the firmware page changes to 0, this falls through to the driver
Start:
lda #$f0 ;restore COUT after PR# called
sta $36
lda #$fd
sta $37
jsr Home ;clear screen and show menu options
ldy #$00
PrintString:
lda Text,y
beq WaitForRPi
ora #$80
jsr PrintChar
iny
bne PrintString
WaitForRPi:
lda InputFlags
rol
bcs OK
lda #$ff
jsr Wait
lda #'.'+$80
jsr PrintChar
jmp WaitForRPi
OK:
jsr Home ;clear screen
lda #MenuCommand ;request menu text from RPi
jsr SendByte
DumpOutput:
jsr GetByte
cmp #$00
beq GetChar
jsr PrintChar
clc
bcc DumpOutput
GetChar:
jsr ReadChar
sec ;subtract ascii "1" to get 0 - 3 from "1" to "4"
sbc #$b1
asl ;put in top nibble as EPROM page
asl
asl
asl
ora #$0f ;set all flags high
jmp PageJump
SendByte:
pha
waitWrite:
lda InputFlags
rol
rol
bcs waitWrite
pla
sta OutputByte
lda #$3e ; set bit 0 low to indicate write started
sta OutputFlags
finishWrite:
lda InputFlags
rol
rol
bcc finishWrite
lda #$3f
sta OutputFlags
rts
GetByte:
lda #$3d ;set read flag low
sta OutputFlags
waitRead:
lda InputFlags
rol
bcs waitRead
lda InputByte
pha
lda #$3f ;set all flags high
sta OutputFlags
finishRead:
lda InputFlags
rol
bcc finishRead
pla
end:
rts
.repeat 183-<end
.byte 0
.endrepeat
Text:
.byte "Apple2-IO-RPi",$8d
.byte "(c)2020-2021 Terence J. Boldt",$8d
.byte $8d
.byte "Waiting for RPi...",$00
.byte <GetByte ;all firmware pages have pointer to GetByte routine here
.byte >GetByte
.byte <SendByte ;all firmware pages have pointer to SendByte routine here
.byte >SendByte
.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