DS1553_OFF_SECONDS
ct.sec = FROMBCD((*sc->sc_read)(dev, DS1553_OFF_SECONDS) &
(*sc->sc_write)(dev, DS1553_OFF_SECONDS, TOBCD(ct.sec) &
sec = (*sc->sc_read)(dev, DS1553_OFF_SECONDS);
(*sc->sc_write)(dev, DS1553_OFF_SECONDS, sec);