RTC_ADDR
outb(RTC_ADDR, RTC_D); /* check if clock valid */
outb(RTC_ADDR, RTC_A); /* check if update in progress */
outb(RTC_ADDR, i);
outb(RTC_ADDR, century); /* do century */
outb(RTC_ADDR, day_alrm);
outb(RTC_ADDR, mon_alrm);
outb(RTC_ADDR, 0); /* re-read Seconds register */
outb(RTC_ADDR, RTC_B);
outb(RTC_ADDR, RTC_B);
outb(RTC_ADDR, i);
outb(RTC_ADDR, century); /* do century */
outb(RTC_ADDR, day_alrm);
outb(RTC_ADDR, mon_alrm);
outb(RTC_ADDR, RTC_B);
outb(RTC_ADDR, RTC_B);