Set cursor in top left corner in clrscr()

as documented in conio.h

libsrc/c1p/clrscr.s

@@ -2,6 +2,8 @@
 ; void clrscr (void);
 ;
         .export         _clrscr
+        .import         plot
+        .importzp       CURS_X, CURS_Y
         .include        "c1p.inc"
 
 ; Adapted from the Challenger Character Graphics
@@ -22,4 +24,8 @@ staloc:
 		bne       staloc
 		lda       #>(SCRNBASE); load high byte
 		sta       staloc+2    ; restore base address
-		rts
+
+		lda       #$00        ; cursor in upper left corner
+        sta       CURS_X
+        sta       CURS_Y
+		jmp       plot        ; Set the cursor position