FCR_DSEL0
sun3x_fdc.fcr |= (FCR_DSEL0 | FCR_EJECT);
sun3x_fdc.fcr &= ~(FCR_DSEL0 | FCR_EJECT);
fcr |= (FCR_DSEL0 | FCR_MTRON);
fcr &= ~(FCR_DSEL0 | FCR_MTRON);