collapseos/blk/584

        IFNZ, ( buffer full? )
            ( no, continue )
            DE ADDHLd, ( restore ACIAW> )
            ( buffer not full, let's write )
            ACIA_IO INAi,
            (HL) A LDrr,
            ( advance W> )
            HL INCd,
            ACIAW> LD(n)HL,
            DE ACIA) LDd(n),
            DE SUBHLd,


                                                      ( cont. )