;Screen Control Assembly Lanuage Routines for Apple II

        SUBROUTINE _SCREEN

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

;Set Screen Mode
SETSCR: CMP SMTEXT  ;If Default Text Screen
        BEQ GETSCR  ;Return Return 0
        LDA #$FF    ;Else Return ERROR
        RTS
                    ;Else Return 0
;Get Screen Mode
GETSCR: LDA #0      ;Return 0 (Default Text Mode)
        RTS

;Clear the Screen
CLRSCR:  EQU $FC58  ;Applesoft Routine HOME

;Move Cursor To Home Position
CRSRHM  LDA #0      ;Set Column to 0
        TAY         ;Set Row to 0
                    ;and Fall into SETPOS

;Move Cursor to Specified Coordinates
SETPOS: STA $24     ;Store Column in CH
        TYA         ;Transfer Row to Accumulator
        JMP $FB5B   ;Exectute Monitor Routine TABV

;Get Cursor Position
GETPOS: LDA $24     ;Load Column from CH
        LDY $25     ;Load Row from CV
        RTS

;Get Screen Size
GETSIZ: LDA $21     ;Load Width from WNDWDTH
        LDY $23     ;Load Height from WNDBTM
        RTS