IOASIC_INTR
bus_space_read_4(sc->sc_bst, sc->sc_bsh, IOASIC_INTR);
IOASIC_INTR, sir);
(DEC_3000_300_IOASIC_ADDR + IOASIC_INTR);
mask = bus_space_read_4(sc->sc_bst, sc->sc_bsh, IOASIC_INTR);