Apple2-IO-RPi/Apple2/MenuFirmware.asm
2021-03-28 11:17:14 -04:00

97 lines
1.9 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
.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 $fc58 ;clear screen and show menu options
ldy #$00
PrintString:
lda Text,y
beq GetChar
ora #$80
jsr $fded
iny
bne PrintString
GetChar:
jsr $fd0c
sec ;subtract ascii "1" to get 0 - 3 from "1" to "4"
sbc #$b1
asl ;put in top nibble as EPROM page
asl
asl
asl
ora #$0f ;set all flags high
jmp PageJump
Text:
.byte "Apple2-IO-RPi",$8d
.byte "(c)2020-2021 Terence J. Boldt",$8d
.byte $8d
.byte "1. Boot",$8d
.byte "2. Command Line",$8d
.byte "3. File Access [NOT IMPLEMENTED]",$8d
.byte $8d
.byte "May take 45 seconds for RPi to start",$8d
.byte "after intial power-on...",$00
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