ATA_PDC_WRITE_REG
bytep[i++] = ATA_PDC_1B | ATA_PDC_WRITE_REG | ATA_PDC_WAIT_NBUSY|ATA_DRIVE;
bytep[i++] = ATA_PDC_2B | ATA_PDC_WRITE_REG | ATA_FEATURE;
bytep[i++] = ATA_PDC_2B | ATA_PDC_WRITE_REG | ATA_COUNT;
bytep[i++] = ATA_PDC_2B | ATA_PDC_WRITE_REG | ATA_SECTOR;
bytep[i++] = ATA_PDC_2B | ATA_PDC_WRITE_REG | ATA_CYL_LSB;
bytep[i++] = ATA_PDC_2B | ATA_PDC_WRITE_REG | ATA_CYL_MSB;
bytep[i++] = ATA_PDC_1B | ATA_PDC_WRITE_REG | ATA_DRIVE;
bytep[i++] = ATA_PDC_1B | ATA_PDC_WRITE_REG | ATA_FEATURE;
bytep[i++] = ATA_PDC_1B | ATA_PDC_WRITE_REG | ATA_COUNT;
bytep[i++] = ATA_PDC_1B | ATA_PDC_WRITE_REG | ATA_SECTOR;
bytep[i++] = ATA_PDC_1B | ATA_PDC_WRITE_REG | ATA_CYL_LSB;
bytep[i++] = ATA_PDC_1B | ATA_PDC_WRITE_REG | ATA_CYL_MSB;
bytep[i++] = ATA_PDC_1B | ATA_PDC_WRITE_REG | ATA_DRIVE;