Bitfields for Intel 82434LX/NX Frame Buffer Range register:
Bit(s)	Description	)
 31-20	buffer offset (in 1MB increments; must be multiple of buffer set set
	  by bits 3-0)
 19-14	reserved
 13	enable byte merging
 12	128K VGA-range Attribute Enable
	when set, bits 13,9,7 also apply to VGA memory range (Axxxx-Bxxxx)
 11-10	reserved
 9	no lock requests
 8	reserved
 7	enable transparent bufer writes
 6-4	reserved
 3-0	buffer size in MB (less 1); must be power of 2
Note:	if bits 31-20=0, the frame buffer feature is disabled
SeeAlso: #01055