INT_CTL0
outb(INT_CTL0, ICW1_AT); /* ICW1 */
outb(irc_no ? INT2_CTL0 : INT_CTL0, OCW3_PL);
data = inb(irc_no ? INT2_CTL0 : INT_CTL0);
outb(INT_CTL0, OCW2_CLEAR | CASCADE_IRQ);
outb(INT_CTL0, OCW2_CLEAR | irq_no);