;Screen Control Assembly Lanuage Routines for VIC-20

                    ;SUBROUTINE

SMTEXT  EQU $00     ;Default Text Screen
SMWIDE  EQU $02     ;Wide Text Screen (Undefined)

;Set Screen Mode
SETSCR: SEC         ;Set Carry
        JSR $FF5F   ;Call SCRMOD
        LDA #0      ;Set Return Value to Zero
        BCC .RETURN ;If Carry Set
        DEC         ;  Return 255 (Error)
.RETURN RTS

;Get Screen Mode
GETSCR: CLC         ;Clear Carry
        JMP $FF5F   ;Execute SCRMOD 
        RTS

;Clear the Screen
CLRSCR  LDA #$93	    ;Load CLR/HOME Character
        JMP PUTCHR  ;and Print to Screen

;Move Cursor To Home Position
CRSRHM  LDA #$13	    ;Load HOME Character
        JMP PUTCHR  ;and Print to Screen

;Move Cursor to Specified Coordinates
SETPOS: .DC $5A ;PHY Copy Row
        .DC $FA ;PLX to X Register,
        TAY         ;Column to Y Register
        CLC         ;Set Carry
        JMP $FFF0   ;and Execute Plot

;Get Cursor Position
GETPOS: LDY $D6     ;Load Cursor Row
        LDA $D3     ;Load Cursor Column
        RTS

;Get Screen Size
GETSIZ: JSR $FFED   ;Call SCREEN Kernal Routine
        TXA         ;Transfer Width to Accumulator
        RTS