Xref: news2.mv.net comp.os.msdos.djgpp:4577
From: Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Accessing physical memory
Date: Mon, 03 Jun 1996 09:10:27 CDT
Organization: Rice University, Houston, Texas
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Message-ID: <31b2f253.sandmann@clio.rice.edu>
References: <000000225732916385822 AT bryanston DOT co DOT uk>
Reply-To: sandmann AT clio DOT rice DOT edu
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To: djgpp AT delorie DOT com
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> Is there a way to access physical memory at a specified address without
> using farptrs or Fat DS?

If you are willing to limit yourself to running under DPMI clients which
support DPMI 1.0 features (like cwsdpmi), yes.  You can map the memory into
a current memory block (something you malloc'ed for example) then access
it there.  This won't work under Windows, OS/2, etc, so if you do it this
way you either limit your portability or must code up the alternate access
methods anyway.

The code for mapping into a malloc()ed block is a bit complicated; you 
might look into the mman.h functions for hints on how to do this if you
already have a copy of the DPMI 1.0 spec and know it by heart.