mirror of
https://github.com/tjboldt/Apple2-IO-RPi.git
synced 2024-06-08 19:29:31 +00:00
228 lines
3.2 KiB
NASM
Executable File
228 lines
3.2 KiB
NASM
Executable File
;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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; hard code slot to 7 for now, will make it auto-detect later
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SLOT = 7
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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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ShellCommand = $09
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InputString = $fd6a
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StringBuffer = $0200
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PrintChar = $fded
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Keyboard = $c000
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ClearKeyboard = $c010
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Home = $fc58
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Wait = $fca8
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PromptChar = $33
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Read80Col = $c01f
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TextPage1 = $c054
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TextPage2 = $c055
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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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BasCalc = $fbc1
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LastChar = $06
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ESC = $9b
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.org $2000
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Start:
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jsr $c300 ; force 80 columns
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lda LastChar
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pha
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bit ClearKeyboard
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lda #ResetCommand
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jsr SendByte
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lda #ShellCommand
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jsr SendByte
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jsr DumpOutput
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pla
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sta LastChar
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rts
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DumpOutput:
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jsr GetByte
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bcs checkInput
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cmp #$00
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beq endOutput
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pha
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jsr ClearCursor
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pla
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cmp #'H'
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beq setColumn
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cmp #'V'
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beq setRow
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cmp #'C'
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beq clearScreen
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cmp #'T'
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beq setTop
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cmp #'B'
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beq setBottom
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cmp #'U'
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beq moveUp
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jsr PrintChar
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jsr SetCursor
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jmp DumpOutput
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checkInput:
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bit Keyboard ;check for keypress
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bpl DumpOutput ;keep dumping output if no keypress
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lda Keyboard ;send keypress to RPi
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and #$7f
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jsr SendByte
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bit ClearKeyboard
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jmp DumpOutput
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endOutput:
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rts
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clearScreen:
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jsr Home
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jsr SetCursor
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jmp DumpOutput
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setColumn:
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jsr GetByte
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sta htab
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sta htab80
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jsr SetCursor
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jmp DumpOutput
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setRow:
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jsr GetByte
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sta vtab
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jsr BasCalc
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jsr SetCursor
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jmp DumpOutput
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setTop:
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jsr GetByte
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sta $22
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jmp DumpOutput
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setBottom:
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jsr GetByte
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sta $23
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jmp DumpOutput
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moveUp:
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dec vtab
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lda vtab
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jsr BasCalc
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jsr SetCursor
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jmp DumpOutput
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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 #$1e ; 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 #$1f
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sta OutputFlags
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rts
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GetByte:
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bit Keyboard ; skip byte read if key pressed
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bcc keyPressed
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lda #$1d ;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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bcc readByte
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bit Keyboard ;keypress will abort waiting to read
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bpl waitRead
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keyPressed:
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lda #$1f ;set all flags high and exit
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sta OutputFlags
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sec ;failure
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rts
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readByte:
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lda InputByte
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pha
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lda #$1f ;set all flags high
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sta OutputFlags
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finishRead:
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lda InputFlags
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rol
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bcc finishRead
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pla
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clc ;success
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end:
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rts
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SetCursor:
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lda htab80 ;get horizontal location / 2
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lsr
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tay
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lda TextPage2
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bcc setChar
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lda TextPage1
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setChar:
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lda (BasL),y
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sta LastChar ; save so ClearCursor will pick it up
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cmp #$e0
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bpl lowerCase
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cmp #$c0
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bpl upperCase
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cmp #$a0
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bpl symbol
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cmp #$80
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bpl noop
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symbol:
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lowerCase:
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invert:
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eor #$80
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jmp storeChar
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upperCase:
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and #$1f
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jmp storeChar
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noop:
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storeChar:
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sta (BasL),y
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lda TextPage1
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rts
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ClearCursor:
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lda htab80 ;get horizontal location / 2
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lsr
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tay
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lda TextPage2
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bcc restoreChar
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lda TextPage1
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restoreChar:
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lda LastChar
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sta (BasL),y
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lda TextPage1
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rts
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