ym_recdrq
if (pnpbios_getdmachan(aa->pbt, aa->resc, 1, &sc->ym_recdrq))
sc->ym_recdrq = sc->ym_playdrq; /* half-duplex mode */
sc->ym_recdrq = sc->ym_playdrq = playdrq->ar_drq;
sc->ym_recdrq = recdrq->ar_drq;
sc->ym_recdrq = ipa->ipa_drq[1].num;