Path: utzoo!utgpu!attcan!uunet!lll-winken!lll-ncis!helios.ee.lbl.gov!pasteur!ames!mailrus!tut.cis.ohio-state.edu!bloom-beacon!bu-cs!mirror!ima!johnl
From: johnl@ima.ima.isc.com (John R. Levine)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Can you use Expanded memory as Extended?
Summary: Yes.
Keywords: PC/AT, RAM, memory, expanded, extended, EMS
Message-ID: <3136@ima.ima.isc.com>
Date: 6 Jan 89 21:05:40 GMT
References: <3129@dalcs.UUCP>
Reply-To: johnl@ima.UUCP (John R. Levine)
Distribution: na
Organization: Segue Software, Inc.
Lines: 24

In article <3129@dalcs.UUCP> lane@dalcs.UUCP (John Wright/Dr. Pat Lane) writes:
>Is there any product, hardware or software, that will let you use
>expanded memory (LIM EMS whatever) as extended, or, vice versa?

On every AT expanded memory board I have ever seen it is possible to set
DIP switches on the board to configure the memory as expanded, extended,
or in many cases a combination of the two.  If you are using an operating
system that runs in protected mode, extended memory is much more useful.

If you are asking if it's possible to flip memory back and forth between
extended and expanded without taking apart your computer, it happens for
free on PS/2 boards and otherwise is as far as I can tell unavailable.

This discussion applies only to 286 machines.  On a 386, you always want
to configure your memory as extended because the 386's on-chip memory mapping
is powerful enough to implement full EMS in software using a driver like QEMM.

Finally, if you have a board that only provides extended memory, there are
programs with names like LIMSIM that provide a partial implementation of EMS
that is adequate for some programs, notably 1-2-3.
-- 
John R. Levine, Segue Software, POB 349, Cambridge MA 02238, +1 617 492 3869
{ bbn | spdcc | decvax | harvard | yale }!ima!johnl, Levine@YALE.something
You're never too old to have a happy childhood.