;
; void clrscr (void);
;
        .export         _clrscr
        .import         plot
        .importzp       CURS_X, CURS_Y
        .include        "osic1p.inc"

; Adapted from the Challenger Character Graphics
; Reference Manual, "2.3.3 MACHINE LANGUAGE SCREEN CLEAR"
; This is self-modifying code!
BANKS = VIDEORAMSIZE / $100

_clrscr:
        lda       #$20 ;' '
		ldy       #BANKS
		ldx       #$00
staloc:
		sta       SCRNBASE,X
		inx
		bne       staloc
		inc       staloc+2
		dey
		bne       staloc
		lda       #>(SCRNBASE); load high byte
		sta       staloc+2    ; restore base address

		lda       #$00        ; cursor in upper left corner
        sta       CURS_X
        sta       CURS_Y
		jmp       plot        ; Set the cursor position