f:
  pha         ; save registers
  tya
  pha             

  ldy #$01    ; crsr of
  sty $cc        
  lda $cf     ; crsr revers?
  beq :+     ; no -> return
  dey         ; set normal phase
  sty $cf        
  ldy $d3     ; get column
  lda $ce     ; restore char
  sta ($d1),y
  lda $0287   ; restore colour
  sta ($f3),y

:
  pla         ; restore registers
  tay
  pla
  rts

; -------------------------------------
; opposite of cursor_off
; -------------------------------------
