Bitfields for Intel 82371/82378/82379 PCI IRQ Route Control Register:
Bit(s)	Description	)
 7	disable IRQ routing
 6-4	reserved (0)
 3-0	ISA IRQ number to which to route the PCI IRQ
Note:	IRQs 0-2, 8, and 13 are reserved
SeeAlso: #01064,#01167,#01100