Bitfields for Intel 82437,82439HX/TX,82443BX/EX/LX SMRAM control register:
Bit(s) Description )
7 reserved
6 SMM Space Open
=1 make SMM DRAM visible even when not in SMM if bit 4 =0
5 SMM Space Closed
=1 no data references permitted to SMM DRAM even in SMM
4 SMM Space Locked
=1 force bits 4 and 6 to become read-only; and clear bit 6
3 SMRAM Enable
=1 128K DRAM are accessible for use at A000 while in SMM
2-0 SMM Space Base Segment
010 segment A000-BFFF
100 segment C000-CFFF (82437MX,82443EX only)
other reserved
Note: bits 5 and 6 must never both be set at the same time
SeeAlso: #01099,#01108,#01098,#01124,#01106,#01107,#01142,#01129