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36 lines
761 B
Plaintext
36 lines
761 B
Plaintext
;Screen Control Assembly Lanuage Routines for C02
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;Skeleton Code for Systems with no Screen Control
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SUBROUTINE _SCREEN
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SMTEXT EQU $00 ;Default Text Screen
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SMWIDE EQU $FF ;Wide Text Screen (Undefined)
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;Set Screen Mode
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SETSCR: CMP #SMTEXT ;If Not Default Text
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BNE GETPOS ;Return Error
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;Else Return 0
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;Get Screen Mode
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GETSCR: LDA #0 ;Return 0 (Default Text Mode)
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RTS
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;Clear the Screen
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CLRSCR: RTS ;No Action
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;Move Cursor Home
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CRSRHM EQU CLRSCR ;No Action
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;Move Cursor to Specified Coordinates
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SETPOS EQU CLRSCR ;No Action
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;Get Cursor Position
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GETPOS: LDA #$FF ;Return Error
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TAY
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RTS
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;Get Screen Size
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GETSIZ LDA #80 ;Return 80x25
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LDY #25
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RTS
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