DAC_INDX_HI
p9100_ramdac_write(sc, DAC_INDX_HI, 0);
p9100_ramdac_write(sc, DAC_INDX_HI, 0);
p9100_ramdac_write(sc, DAC_INDX_HI, 1);
p9100_ramdac_write(sc, DAC_INDX_HI, (off & 0xff00) >> 8);
p9100_ramdac_write(sc, DAC_INDX_HI, (off & 0xff00) >> 8);