Date: Tue, 29 Apr 1997 11:45:19 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Demmer AT LStM DOT Ruhr-Uni-Bochum DOT De
cc: djgpp AT delorie DOT com
Subject: Re: Need help on DMA transfer
In-Reply-To: <5E6E9801EF3@brain1.lstm.ruhr-uni-bochum.de>
Message-ID: <Pine.SUN.3.91.970429114459.23034J-100000@is>
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On Mon, 28 Apr 1997, Tom Demmer wrote:

>  - Can the DMA buffer be above 1 MB, or _must_ I transfer from/to
>    DOS memory?

AFAIK, if it is above 1MB, you will have to use VDS (Virtual DMA
Services) to make sure the DMA buffer is mapped to a certain physical
address.  Otherwise, the memory-mapping mechanism will cause the DMA
controller to reference a wrong memory area.

VDS is available with most memory managers (and Windows), but if you
need to run on vanilla DOS (no EMM/QEMM, just CWSDPMI), you don't have
VDS.