mirror of
https://github.com/tjboldt/Apple2-IO-RPi.git
synced 2024-11-15 18:06:11 +00:00
173 lines
2.9 KiB
NASM
173 lines
2.9 KiB
NASM
; Copyright Terence J. Boldt (c)2020-2023
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; Use of this source code is governed by an MIT
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; license that can be found in the LICENSE file.
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; This file contains the source for the firmware
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; that displays the copyright message on boot
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; and checks for the RPi status to be ready before
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; attempting to boot
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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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ResetCommand = $00
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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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MenuCommand = $08
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Wait = $fca8
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PrintChar = $fded
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Home = $fc58
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ReadChar = $fd0c
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BasCalc = $fbc1
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htab = $24
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vtab = $25
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BasL = $28
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htab80 = $057b
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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 1 of EPROMi
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PageJump:
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sta OutputFlags
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jmp Start
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;entry points for ProDOS
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DriverEntry:
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lda #$0f ;set all flags high and page 0 of EPROM
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sta OutputFlags
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;since the firmware page changes to 0, this falls through to the driver
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Start:
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lda #$f0 ;restore COUT after PR# called
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sta $36
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lda #$fd
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sta $37
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;jsr Home ;clear screen and show menu options
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lda #$10
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sta vtab
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jsr BasCalc
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ldy #$00
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PrintString:
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lda Text,y
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beq WaitForRPi
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ora #$80
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jsr PrintChar
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iny
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bne PrintString
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WaitForRPi:
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lda InputFlags
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rol
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bcs Reset
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lda #$ff
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jsr Wait
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lda #'.'+$80
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jsr PrintChar
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jmp WaitForRPi
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Reset:
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lda #'_'|$80
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jsr PrintChar
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lda #ResetCommand
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jsr SendByte
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lda #$88
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jsr PrintChar
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lda #'.'|$80
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jsr PrintChar
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jsr GetByte
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beq Ok
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jmp Reset
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Ok:
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lda #$8D
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jsr PrintChar
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lda #'O'|$80
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jsr PrintChar
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lda #'K'|$80
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jsr PrintChar
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Boot:
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lda #$0f
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jmp PageJump
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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 #$3e ; 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 #$3f
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sta OutputFlags
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rts
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GetByte:
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lda #$3d ;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 #$3f ;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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; NOTE: The text below exactly fills the remaining 256 bytes of firmware
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Text:
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.byte "Apple2-IO-RPi",$8d
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.byte "(c)2020-2023 Terence J. Boldt",$8d
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.byte $8d
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.byte "Waiting for RPi FW:000F...",$00
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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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