IFZ, ( end of buffer reached? )
                ( yes )
                ( +4 == ACIA( )
                ACIA_MEM 4 + LDHL(n),
                ( +2 == ACIAW> )
                ACIA_MEM 2+ LD(n)HL,
            THEN,
        THEN,
    THEN,
    DE POP, HL POP, AF POP,
    EI, RETI,