Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.unix.sysv386
Subject: Re: Simultaneous DMA
Message-ID: <1991Apr07.145531.22860@virtech.uucp>
Date: 7 Apr 91 14:55:31 GMT
References: <2247@pdxgate.UUCP>
Organization: Virtual Technologies Inc.
Lines: 27

brians@eecs.cs.pdx.edu (Brian Smith) writes:

>The manual for Interactive Unix states that it is possible for some DMA chips
>to malfunction when more than one allocated DMA channel is used simultaneously.
>Is there any way to tell whether a motherboard has this defect?  One of the
>boards in my system which uses DMA is the SCSI disk controller, so I'd rather
>not test this under Unix and risk losing my filesystem.  Even a DOS program
>to test for this problem would be fine.

You have two questions.  

	1. can my motherboard do simultaneous DMAs 
	2. can my motherboard do bus mastering DMA (the scsi card)

The Fastback backup software for dos, as part of it's installation, tests
the abilities of the DMA controller with respect to question 1.  I don't 
know of any tests for question 2 other than install and see how it 
works. (Be sure to have a backup before you start).

>My motherboard is the AMI Voyager 486-25.

My AMI 386/33 dies when bus-mastering DMA is attempted.

-- 
Conor P. Cahill            (703)430-9247        Virtual Technologies, Inc.
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