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From: amichiel@rodan.acs.syr.edu (Allen J Michielsen)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: EMS hardware vs. software emulation
Message-ID: <1991Jan9.163046.25355@rodan.acs.syr.edu>
Date: 9 Jan 91 16:30:46 GMT
References: <37694@cup.portal.com> <5182@bwdls58.UUCP>
Sender: amichiel@sunrise.acs.syr.edu
Organization: Syracuse University, Syracuse, NY
Lines: 40

In article <5182@bwdls58.UUCP> mlord@bwdls58.bnr.ca (Mark Lord) writes:
>In article <37694@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson)
><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?
>
>Thousands and thousands of us do this all of the time, with no problems other
>than slightly greater interrupt latencies due to the V86 mode
>We run QEMM386, or 386^MAX, or EMM386.SYS, or..

   Expecting or even asking mfg's to include EMS in hardware is stupid.  First
of all, EMS is dead.  In several years little or nothing will support it.  EXT
is much better, faster, and usable to software that is coming out.  Look at all
large packages (in price & function/not poplarity), autocad, mathmatica, Splus
(statistics package which clones a major IBM mainframe package), lotus 3.1.
All support extended directly, else support extended better than expanded,
else support extended exclusively.  LArger and more complex packages become
even more complex, and slower using expanded memory.
   Then there's the problem of ems version compatability.  WHat happens when
you have a application that requires a newer or older ems version compatability
or for some odd reason, requires a different (non-standard) address mapping.
Or what happens when you buy a system to network and can't integrate into your
network because the ems emulator uses the address range of you already site
and network standard interface card.  Then should be bang on these mfg's to
have untold switches or software interfaces & programming in order to change
or select the remapped address range and compatability as needed ?
   Extended memory is the best thing under all circumstances.  It is completely
linear and available to anybody that writes software that isn't xt specific.
Expanded memory is the next best thing, and the only game in town for old
software and limited cpu's (like the 8088/8086/80186).
al

-- 
Al. Michielsen, Mechanical & Aerospace Engineering, Syracuse University
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