Date:	Wed, 28 Aug 1996 16:11:55 +0800 (GMT)
From:	Orlando Andico <orly AT gibson DOT eee DOT upd DOT edu DOT ph>
To:	Elliott Oti <e DOT oti AT stud DOT warande DOT ruu DOT nl>
cc:	djgpp AT delorie DOT com
Subject:	Re: what is dpmi....
In-Reply-To:	<3223574F.43AE@stud.warande.ruu.nl>
Message-ID:	<Pine.SGI.3.93.960828160811.16631A-100000@gibson.eee.upd.edu.ph>
MIME-Version:	1.0

On Tue, 27 Aug 1996, Elliott Oti wrote:

> In the good old days,right after 640k was enough for everyone,people started 
> pluggin' extra memory into their PC's, and Intel developed this newfangled
> workstation chip called the 80286 which had a thing called protected mode.
> In order to access that extra memory, MS, Intel and Lotus developed the
> Expanded Memory specification (EMS) to handle expanded memory, and later the
> Extended Memory Specification (XMS) for extended memory above 1Mb.
> Out of the two standards,and to cope with this new 286 protected mode thingy ,
> the VCPI and later DPMI standards developed.

Not quite correct. VCPI was not developed precisely for the 286 protected
mode, but for EMS. Quarterdeck (which developed VCPI along with DESQview)
seems to have loved EMS a great deal. Also, AFAIK unless you had an EMS
4.0 memory board, you couldn't use VCPI on anything less than a 386. DPMI
however will run on a 286, albeit what's the use. The primary difference
between DPMI and VCPI (excepting the fact that VCPI is all but dead; DJGPP
used to support it but no longer) is that VCPI programs run at ring 0
(like the barebones CWSDPMI) so you don't have fancy things like memory
protection. That's the main reason I think why everyone dumped it for
DPMI, of course alongside the fact that all the Windoze-using masses have
a free DPMI server.

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