Re: Memory between 640K-1M

Gabriel Paubert (
Sun, 17 May 1998 14:00:00 +0200 (METDST)

On Sun, 17 May 1998, Anthony Barbachan wrote:

> I was wondering if any of the 384K RAM between 640K-1M, not being used by
> adapters or shadowing, might be usable for something. I can't remember if
> this area was set aside by DOS or by the PC's original architecture. It
> seams wasteful to continue to just mark it as reserved. If usable, some of
> this memory could give some of those memory starved machines out there some
> more breathing room.

It was set aside by the original IBM PC, do not forget that the 8088 could
address (only?) 1Mb of memory and you had to put the BIOS (including
a Basic interpreter AFAIR) and the I/O adapters somewhere in this

There are patches floating around for this but you should also check your
BIOS setup. For example, my first MoBo (25MHz 486DX in 1991) with an Opti
chipset had the option to remap 256kB of this unused memory above the
SIMM. So a 4Mb machine became a 4.25Mb one (it no more worked when I
upgraded the machine to 16Mb because of a caching limit, but then I didn't
care anymore).


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to