collapseos/blk/584

        IFNZ, ( buffer full? )
            ( no, continue )
            DE ADDHLss, ( restore ACIAW> )
            ( buffer not full, let's write )
            ACIA_IO INAn,
            (HL) A LDrr,
            ( advance W> )
            HL INCss,
            ( +2 == ACIAW> )
            ACIA_MEM 2+ LD(nn)HL,
            ( +6 == ACIA) )
            DE ACIA_MEM 6 + LDdd(nn),
            DE SUBHLss,


                                                      ( cont. )