EMS hardware vs. software emulation

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#6664

From: Mark Robert Thorson
Date: Mon, 07 Jan 1991 18:41

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It seems to me that anyone who designs a system with a 286, 386, or 486
with more than 1M of memory should include hardware EMS registers and mapping
logic, unless he only plans to run Unix.  At first, I thought maybe only
the 286 needs it, because the other chips have paging.  But then I remembered
that all the DOS people run in real-address mode, so the paging mechanism
is disabled.  The only way around this would be to run your DOS applications
in virtual-8086 mode, but I don't think anybody does that, do they?

Am I right?  Is omission of the EMS hardware in a 2/3/486 >1M system
a cardinal sin?  The reason I ask is that there are chipsets on the
market for building PC-compatible system boards with for example
a 386 and 16M but don't have hardware EMS.  Does that mean any memory
above 1M is mostly useless (i.e. real slow due to software EMS emulation)?

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!usc!apple!portal!cup.portal.com!mmm
From: mmm@cup.portal.com (Mark Robert Thorson)
Newsgroups: comp.sys.ibm.pc.misc
Subject: EMS hardware vs. software emulation
Message-ID: <37694@cup.portal.com>
Date: 7 Jan 91 18:41:23 GMT
Organization: The Portal System (TM)
Lines: 13