; Copyright Terence J. Boldt (c)2020-2024 ; Use of this source code is governed by an MIT ; license that can be found in the LICENSE file. ; This file formerly contained the source for the ; firmware that had a file access ; but is now empty except required common bytes ;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 .org SLOT*$100 + $C000 ;ID bytes for booting and drive detection cpx #$20 ;ID bytes for ProDOS cpx #$00 ; cpx #$03 ; cpx #$3C ;ID byte for Autostart ROM lda #$3f ;set all flags high and page 3 of EPROM for menu jmp PageJump ;The following bytes must exist in this location for Pascal communications ;as they are standard pointers for entry points .byte CommInit&$00FF ;low byte of rts for init of Pascal comms .byte $43 ; low byte of read for Pascal comms .byte $49 ; low byte of write for Pascal comms .byte $4F ; low byte of rts for status of Pascal comms CommInit: lda #$0f ; set all flags high and page 0 for comm driver sta OutputFlags ldx #$00 ; set error code to 0 for success rts PageJump: sta OutputFlags jmp Start ;this jump is only called if coming in from PageJump with A=$0f ;entry points for ProDOS DriverEntry: lda #$0f ;set all flags high and page 0 of EPROM sta OutputFlags jmp Start ; this is never called as the EPROM page changes ;load first two blocks and execute to boot Start: end: rts .repeat 251-