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From: Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: DPMI memory -- what is it?
Date: Sat, 02 Dec 1995 09:48:53 CST
Organization: Rice University, Houston, Texas
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References: <DIxHEF DOT EMr AT jade DOT mv DOT net>
Reply-To: sandmann AT clio DOT rice DOT edu
Nntp-Posting-Host: clio.rice.edu
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Dj-Gateway: from newsgroup comp.os.msdos.djgpp

> I've heard a LOT about dpmi memory.. I know version 1.x of djgpp supports it,
> and 2.0 uses dpmi memory explicitly. But, what IS dpmi memory, how is it used,
> and what are the advantages/disadvantages of using it???

DPMI is DOS Protected Mode Interface.  It is an industry standard API.  It is
the *ONLY* way to access 32-bit mode under protected mode environments like
Windows, OS/2, NT, etc.  Since it's the only game in town with some
environments, the advantage of using DPMI is that there is only 1 API to
support.  Under V1.x right now, you get differences in behavior under DPMI or
non-DPMI modes, which makes it difficult to write code for both environments.
The disadvantage is you have less flexibility in how you can manage the 
memory, since this is dictated by the API.  Thus the virtual linear frame
buffer graphics cannot be supported under all environments.