qvaux_read1
status = qvaux_read1(sc, sc->sc_dr.dr_dcd) | sc->sc_dsr;
status = qvaux_read1(sc, sc->sc_dr.dr_ring);
status = qvaux_read1(sc, sc->sc_dr.dr_dtr);
qvaux_read1(sc, sc->sc_dr.dr_dtr) | bit);
qvaux_read1(sc, sc->sc_dr.dr_dtr) & ~bit);