Newsgroups: comp.sys.ibm.pc
Path: utzoo!utgpu!jarvis.csri.toronto.edu!godzilla.eecg.toronto.edu!noworol
From: noworol@eecg.toronto.edu (Mark Noworolski)
Subject: DMA use on the IBM PC
Message-ID: <89Feb11.125002est.2666@godzilla.eecg.toronto.edu>
Summary: frustrated, how to do? 
Organization: EECG, University of Toronto
Distribution: na
Date: Sat, 11 Feb 89 12:49:59 EST

I have been trying to interface to a DMA channel in the PC (DMARQ3).
Well success has been limited- yesterday I fried my hard disk controller
(if anybody has an old 10Meg hard disk controller they want to unload-
there's a market here).

I have a circuit built (using open collector drivers) which generates DMA
requests. I'm programming the DMA chip to do a single transfer and using
the IOR pin as an output enable. I only turn it on once I'm in debug
(so that nothing is using that channel).

Is there something that I should be looking out for? Could there be something
else holding the DMA channel?

Usually what happens is that midway through my programming of the 8237
the computer crashes with a parity error.

Are there any good books/ reference material indicating the proper way to do
DMA transfers on the PC (and how to interface into it)?

Thanks in advance
mark
-- 
There's a really fine line between stupid and clever.

	Nigel - Lead Guitar, Spinal Tap

noworol@ecf.toronto.edu