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From:	Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Getting the physical address of allocated virtual memory
Date:	Sat, 09 Dec 1995 10:55:01 CST
Organization:	Rice University, Houston, Texas
Lines:	11
References:	<DJ9z5C DOT EK0 AT jade DOT mv DOT net>
Reply-To:	sandmann AT clio DOT rice DOT edu
Nntp-Posting-Host:	clio.rice.edu
To:	djgpp AT sun DOT soe DOT clarkson DOT edu
Dj-Gateway:	from newsgroup comp.os.msdos.djgpp

> These cards use DMA to transfer data to and from the PC's memory, and 
> therefore require to know the physical address of the data.  The full 
> configuration will require between 1 and 3Mb of data transfer area!

Putting DMA buffers outside of the 640K area is a non-trivial task.  If
you know you are going to be working under a single environment (like
CWSDPMI) then there are some specific things which can be done to get
this information.  In general, you need to look at the VDS specification
which describes the various options for this support.  But I know 
CWSDPMI doesn't support VDS itself (it might layered under the appropriate
VCPI).  This is really a messy area, but it can be solved with some work.

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