Date: Sun, 12 May 1996 10:12:01 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Shawn Hargreaves <slh100 AT york DOT ac DOT uk>
Cc: djgpp AT delorie DOT com
Subject: Re: How to program DMA
In-Reply-To: <Pine.SGI.3.91.960510093803.12368A-100000@tower.york.ac.uk>
Message-Id: <Pine.SUN.3.91.960512100900.25343H-100000@is>
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On Fri, 10 May 1996, Shawn Hargreaves wrote:

> but it is very sketchy. It's also complicated under djgpp by the fact that 
> the DMA buffer usually has to be in the low megabyte of physical memory, 
> so you need to use special DPMI calls to allocate DOS memory. There is 
> some code that does this in my Allegro library (checkout dma.c and sb.c).

There is also the VDS (virtual DMA services) API that should let you 
solve the problems with the DMA and memory mapping.  The problem is that 
you need a memory manager that supports VDS to use it, so it won't work 
e.g. on a machine that runs CWSDPMI with raw memory or XMS.