Bitfields for AMD-640 PCI Arbitration Control 2 register:
Bit(s)	Description	)
 7	enable initiator priority rotation
	=0 use arbitration priority as set by offset 75h bit 7 (see #01009)
 6	reserved (0)
 5-4	initiator priority rotation control
	00 disabled (use offset 75h bit 7 setting)
	01 grant to processor after every PCI initiator grant
	10 grant to processor after every other PCI initiator grant
	11 grant to processor after every three PCI initiator grants
 3-0	reserved (0)
SeeAlso: #00983,#01009