UMSR_CTS
if (ISSET(combits, UMSR_CTS))
ttytstamp(tp, old_msr & UMSR_CTS, sc->sc_msr & UMSR_CTS,
sc->sc_msr |= UMSR_CTS;
sc->sc_msr &= ~UMSR_CTS;
sc->sc_msr |= UMSR_CTS;
SET(sc->sc_msr, UMSR_CTS);