Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!mcsun!cernvax!chx400!ethz!forty2!eichi
From: eichi@forty2.UUCP (Stefan Eichenberger)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Why is DOS limited to 640K?
Message-ID: <913@forty2.UUCP>
Date: 16 Oct 89 08:48:12 GMT
References: <8909270503.AA28536@euler.Berkeley.EDU> <10253@cbnews.ATT.COM>
Reply-To: eichi@forty2.UUCP (Stefan Eichenberger)
Organization: Exp. Physics University Zuerich
Lines: 22

In article <10253@cbnews.ATT.COM> rock@cbnews.ATT.COM (Y. Rock Lee,55212,cb,1J312E,6148604774) writes:
>Why is a plain DOS limited to 640K memory?

It's sort of clear to me that DOS memory mamgement assumes a 8088 processor,
which can only address 1MByte. And IBM decided towards the end of last century,
that 384KBytes should be reserved for all imaginable 'system' requirements in
the next 100 MYears (such as Display Memory, ROM, EMS, ...)

The question that bothers me: If one doesn't have an EGA or VGA card, but
only CGA, memory between A000 and B800 is not used by anything. There is hard-
ware available to fill this hole with 96 K of additional RAM. But how to make
DOS avare of it? ... I know, there are programs, if you backfill the memory
with some of the LIM 4.0 memory cards or EEMS, or if you have a 80386.
My problem is, I've just conventional memory at that address, an 8086 processor
and no software yet to use it. Any ideas?


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UUCP:      ...mcvax!cernvax!forty2!eichi         Stefan Eichenberger
BITNET:    K807817@CZHRZU1A                      University of Zurich
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