  start of colour line
; $0286    colour

; --- these variables become updated ---
;     on crsr switching.
;
; $cc    crsr flag, 0 = on
; $cd    crsr blink counter
; $ce    char under crsr
; $cf    crsr blink phase, 0 normal
; $0287  colour under crsr



; -------------------------------------
; switch curser off and restore char.
; this has to be done before every crsr
; movement.
; After movement there has to be a jump
; to cursor_on.
; -------------------------------------
cursor_of