: (key)
    ( inc then fetch )
    ACIAR> @ 1+ DUP ACIA) @ = IF
        DROP ACIA( @
    THEN
    ( As long as R> == W>-1, it means that buffer is empty )
    BEGIN DUP ACIAW> @ = NOT UNTIL
    ACIAR> !
    ACIAR> @ C@
;
: (emit)
    ( As long at CTL bit 1 is low, we are transmitting. wait )
    BEGIN [ ACIA_CTL LITN ] PC@ 0x02 AND UNTIL
    ( The way is clear, go! )
    [ ACIA_IO LITN ] PC!
;