Bitfields for Intel 82371 X-Bus Chip Select Enable (high byte):
Bit(s)	Description	)
 7-3	reserved
 2	(82371AB) enable positive PCI decode for Micro Controller at PORTs 62h
	  and 66h
 1	(82371AB) enable one-megabyte extended BIOS (FFF00000h-FFF7FFFFh are
	  forwarded to ISA bus, aliased to top of 16M region)
 0	enable I/O APIC
SeeAlso: #01089