Bitfields for AMD-640 System Performance Control Register:
Bit(s)	Description	)
 7	enable read-around-write
 6	enable cache read pipeline cycle
 5	enable cache write pipeline cycle
 4	enable DRAM pipeline cycle
 3	enable PCI Peer Concurrence (PCI initiator can transfer to another
	  PCI device without blocking memory or CPU bus)
 2-0	reserved (0)
SeeAlso: #00983,#00986