Apple2-IO-RPi/Apple2/MenuFirmware.asm

88 lines
1.6 KiB
NASM
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2021-03-27 14:25:42 +00:00
;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
OutputByte = $c08d
InputFlags = $c08b
OutputFlags = $c087
ReadBlockCommand = $01
WriteBlockCommand = $02
GetTimeCommand = $03
ChangeDriveCommand = $04
ExecCommand = $05
LoadFileCommand = $06
SaveFileCommand = $07
.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 #$1f ;set all flags high and page 1 of EPROMi
PageJump:
sta OutputFlags,x
jmp Start
;entry points for ProDOS
DriverEntry:
lda #$0f ;set all flags high and page 0 of EPROM
sta OutputFlags,x
;since the firmware page changes to 0, this falls through to the driver
Start:
jsr $fc58
ldy #$00
PrintString:
lda Text,y
ora #$80
beq GetChar
jsr $fded
iny
bne PrintString
GetChar:
jsr $fd1b
sec ;subtract ascii "1" to get 0 - 3 from "1" to "4"
sbc #$b1
asl ;put in top nibble as EPROM page
asl
asl
asl
ora #$0f ;set all flags high
jmp PageJump
Text:
.byte "1. Boot",$8d
.byte "2. Set Clock",$8d
.byte "3. Command Line",$8d
.byte "4. File Access",$8d
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