Date: Mon, 12 Jun 2000 15:35:23 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
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To: djgpp AT delorie DOT com
Subject: Re: far pointers
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On Sun, 11 Jun 2000, Alexei A. Frounze wrote:

> > > I don't understand what V86 has to do with remapping of memory.
> > 
> > It turns on the MMU, without which this remapping is impossible.
> > 
> > > It's related to the MMU and V86 has nothing to do with the MMU.
> > 
> > Then please explain why remapping extended memory into the region between
> > 640K and 1MB is impossible in plain real mode.
> 
> Page translation is possible in PMode only.

Yes, that's exactly what I said above: remapping is not possible in
RM, therefore V86 was introduced to enable the MMU and still keep the
real-mode addressing.

> > Compare this with CWSDPMI that runs on top of HIMEM.SYS.  You do not have
> > V86 there, but HIMEM is still used to switch into PM.
> 
> Btw, HIMEM.SYS uses BIOS Int 15h fn 87h for data copying.

I wasn't talking about data copying, I was talking about switching
into PM, in order to run protected-mode code.