[comp.sys.ibm.pc.hardware] How can I prevent memory backfill on old Memory Expansion Cards?

sonny@charybdis.harris-atd.com (Bob Davis) (06/03/91)

	I have a couple of older Memory Expansion Cards and they
both seem to believe that one has a current memory size of either
256K, 512K, or 640K. Consequently, both cards seem to INSIST on
backfilling at least some memory to get up to the 1024K point.

	I am trying to use these cards on a system in which I 
have the first 1 Meg *already* installed. When I tell these
cards that I have 640K of Base memory and to use a start address
for the expansion memory at 1 Meg, 384K of memory disappears somewhere.
Evidently, the expansion card believes it *must* backfill the 384K
above my 640K Base to get to 1 Meg before adding further memory.
Surely, then, 384K on the card must OVERLAP RAM that I already have.

	First of all, does this overlapping cause any problem?
(RAM memory testing indicates no problems.)

	Secondly, is there some way to prevent the backfilling so
that no overlap occurs and I get 384K more memory?

	Thanks
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