  ; end of scroll reg?  
  beq @dont_scroll_yet     ; we don't want to trigger a scroll of the whole screen unless
                                    ; we are actually writing a char. we shouldn't scroll just when
                                    ; writing to the bottom right hand screen (else e.g. the title bar 
                                    ; in 'nano' gets pushed off the top of the screen.
                                    ;
  cpy #$27    ; col = 39?
  beq move_to_next_line   ; yes -> 