EMU_TIMER
emu_wr(sc, EMU_TIMER, sc->timerinterval & 0x03ff, 2);
emu_wr(sc, EMU_TIMER, sc->timerinterval & 0x03ff, 2);
emu_wr(sc, EMU_TIMER, sc->timerinterval & 0x03ff, 2);
#define EMU_TIMER_RATE EMU_MKSUBREG(10, 0, EMU_TIMER)