Date:	Mon, 12 Jun 2000 15:34:54 +0300 (IDT)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	djgpp AT delorie DOT com
Subject:	Re: far pointers
In-Reply-To:	<394378D4.90FA4822@the_messasge_body.com>
Message-ID:	<Pine.SUN.3.91.1000612153441.5082F-100000@is>
MIME-Version:	1.0
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

On Sun, 11 Jun 2000, Alexei A. Frounze wrote:

> > The point is that it is IMHO misleading to say that V86 *allows* DOS and
> > PM programs to coexist.  V86 has nothing to do with PM programs that use
> > DOS.  It makes the mode switch faster in some cases, but that about all
> > it does for PM programs.
> 
> Okay, if you like to change CPU mode completely and waste time, you're
> welcome. If you wanna miss advantages of PMode you're welcome too. But
> infact, V86 is the better way to have both PMode stuff and real-mode
> programs.

That's a different issue, it's not what I commented about.

> >    [V86] means programs like DOS can coexist with protected-mode programs.
> > 
> > My comment was that this is misleading, because V86 does nothing to
> > *allow* coexistence between DOS and PM programs.  They can coexist with
> > or without V86, 
> 
> But not always. :) Switching back to real mode implies that 1st MB must be
> free for that.

Not true.  All you need is that DOS and BIOS code/data be in memory,
which is always so on a DOS machine.

CWSDPMI can run DJGPP programs on a machine with no V86, only 64KB of
conventional memory, and NO extended memory.  It was demonstrated to
work (albeit slowly, with lots of paging).  So there's no need to have
1MB free.

- Raw text -