Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!crdgw1!crdos1!davidsen
From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: comp.os.msdos.misc
Subject: Re: Does MSDOS 5.0 support Upper Memory on a 286?
Message-ID: <3464@crdos1.crd.ge.COM>
Date: 25 Jun 91 13:20:07 GMT
References: <811@wa3wbu.UUCP> <1991Jun21.082150.11675@csc.canberra.edu.au> <46R4MKP@dri.com>
Reply-To: davidsen@crdos1.crd.ge.com (bill davidsen)
Organization: GE Corp R&D Center, Schenectady NY
Lines: 16


  I think you are confusing high memory with upper memory. High memory
starts at FFFF:0000 and goes up, on both [23]86. UMA is between C000 and
F000 (or maybe B000 is the manager is smart enough to sneak under the
VGA). So on a 286 you get 64k for the DOS, but not the memory space for
the UMA.

  Since the 286 doesn't have the right hardware to do UMA, it would have
to be faked in software. The software would take about as much space as
it saved. No gain, so they didn't do it. I think you could do it in
less, but that's the condition which prevails. You still save 64k, which
would seem useful.
-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
  GE Corp R&D Center, Information Systems Operation, tech support group
  Moderator comp.binaries.ibm.pc and 386-users digest.