mirror of
https://github.com/tjboldt/Apple2-IO-RPi.git
synced 2024-11-25 21:33:15 +00:00
102 lines
1.7 KiB
NASM
102 lines
1.7 KiB
NASM
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;ProDOS Zero Page
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Command = $42 ;ProDOS Command
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Unit = $43 ;ProDOS unit (SDDD0000)
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BufferLo = $44
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BufferHi = $45
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BlockLo = $46
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BlockHi = $47
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; ProDOS Error Codes
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IOError = $27
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NoDevice = $28
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WriteProtect = $2B
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InputByte = $c08e+SLOT*$10
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OutputByte = $c08d+SLOT*$10
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InputFlags = $c08b+SLOT*$10
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OutputFlags = $c087+SLOT*$10
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ReadBlockCommand = $01
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WriteBlockCommand = $02
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GetTimeCommand = $03
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ChangeDriveCommand = $04
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ExecCommand = $05
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LoadFileCommand = $06
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SaveFileCommand = $07
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.org SLOT*$100 + $C000
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;ID bytes for booting and drive detection
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cpx #$20 ;ID bytes for ProDOS and the
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cpx #$00 ; Apple Autostart ROM
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cpx #$03 ;
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ldx #SLOT*$10
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stx $2b
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stx Unit
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;force EPROM to second page on boot
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lda #$3f ;set all flags high and page 3 of EPROM for menu
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PageJump:
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sta OutputFlags
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jmp Start ;this jump is only called if coming in from PageJump with A=$2f
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;entry points for ProDOS
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DriverEntry:
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lda #$0f ;set all flags high and page 0 of EPROM
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sta OutputFlags
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Start:
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; Put command firmware here
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;
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;
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;
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SendByte:
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pha
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waitWrite:
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lda InputFlags
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rol
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rol
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bcs waitWrite
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pla
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sta OutputByte
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lda #$0e ; set bit 0 low to indicate write started
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sta OutputFlags
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finishWrite:
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lda InputFlags
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rol
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rol
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bcc finishWrite
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lda #$0f
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sta OutputFlags
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rts
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GetByte:
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lda #$0d ;set read flag low
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sta OutputFlags
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waitRead:
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lda InputFlags
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rol
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bcs waitRead
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lda InputByte
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pha
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lda #$0f ;set all flags high
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sta OutputFlags
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finishRead:
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lda InputFlags
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rol
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bcc finishRead
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pla
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end:
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rts
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.repeat 251-<end
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.byte 0
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.endrepeat
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.byte 0,0 ;0000 blocks = check status
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.byte 7 ;bit set(0=status 1=read 2=write) unset(3=format, 4/5=number of volumes, 6=interruptable, 7=removable)
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.byte DriverEntry&$00FF ;low byte of entry
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