Microsoft KB Archive/35680
HIMEM.SYS Supports Compaq High Memory on 80386 Systems PSS ID Number: Q35680 Article last modified on 01-05-1989
Beginning with HIMEM.SYS Version 2.03, this Microsoft XMS device driver implements support for Compaq High Memory, also known as Built-In Memory (BIM). Although this form of 80386 (and 80386sx) memory architecture is not part of the IBM AT architecture design, it has nonetheless been adopted by some other PC manufacturers. HIMEM.SYS uses this BIM memory as extended memory in its distribution of extended-memory blocks (EMBs). This Built-In Memory is basically some extra memory on the motherboard which is not addressable in the 0-640K region, and is thus moved to the top of available extended memory. In some circumstances, with certain video adaptor cards, some of this memory is used by the video card. Refer to the appropriate Compaq (or other OEM) 80386 system hardware technical reference manual for more information on this special form of memory.
Copyright Microsoft Corporation 1989.