3?
  bcc @got_line_vector
  iny
  cpx #$14      ; line < 20?
  bcc @got_line_vector
  iny           ; line 20-24
@got_line_vector:
  sty temp_ptr_x+1
  tya
  clc           ; colour RAM =
  adc #$d4      ; video RAM + d4
  sta temp_ptr_y+1        
  rts



; -------------------------------------
; init routines
;
; -------------------------------------


initialise_screen:

 ;--- set background ---
  lda #text_background_colour
  sta $d021
; --- disable Shift C= ---
  lda #$80
  