Message-Id: <200006100652.JAA14812@mailgw1.netvision.net.il>
Date: Sat, 10 Jun 2000 09:50:43 +0200
X-Mailer: Emacs 20.6 (via feedmail 8.1.emacs20_6 I) and Blat ver 1.8.5b
From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
To: Prashant TR <prashant_tr AT yahoo DOT com>
CC: djgpp AT delorie DOT com
In-reply-to: <m3k8fymi6l.fsf@vsnl.net.in> (message from Prashant TR on 10 Jun
	2000 07:05:46 +0530)
Subject: Re: far pointers
References: <39405DEE DOT 89226F7B AT ccs DOT iitb DOT ernet DOT in> <m3d7lrxohw DOT fsf AT vsnl DOT net DOT in> <m3itviofxb DOT fsf AT vsnl DOT net DOT in> <39415453 DOT 5E434718 AT is DOT elta DOT co DOT il> <394173D0 DOT 3EF74969 AT the_message_body DOT com> <m3k8fymi6l DOT fsf AT vsnl DOT net DOT in>
Reply-To: djgpp AT delorie DOT com
Errors-To: nobody AT delorie DOT com
X-Mailing-List: djgpp AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk

> From: Prashant TR <prashant_tr AT yahoo DOT com>
> Newsgroups: comp.os.msdos.djgpp
> Date: 10 Jun 2000 07:05:46 +0530
> 
> > :) V86 mode was invented to provide compatibility with old 8086 stuff while
> > CPU is in PMode. DOS itself works normally in V86.
> 
> That's right. Usually, even plain DOS runs in V86 mode because the
> EMM386 driver switches to V86 when it gets installed.

V86 was invented because it allowed to use more than 640KB of memory,
by remapping some of the extended memory into the unused addresses
between 640K and 1MB.  Such remapping is impossible in real mode,
because the MMU is (effectively) inactive.  So they needed to have
protected mode, but with the normal real-mode addressing still
working.

However, this has nothing to do with PM programs and DOS coexisting
together.  PM programs still cannot run in V86 mode without the kind
of trickery that DJGPP does when it calls DOS.