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From: plocher%sally@Sun.COM (John Plocher)
Newsgroups: comp.unix.microport
Subject: Re: Sys V/AT strange floppy problem
Message-ID: <103727@sun.Eng.Sun.COM>
Date: 8 May 89 22:58:38 GMT
References: <11944@grebyn.COM>
Sender: news@sun.Eng.Sun.COM
Reply-To: plocher@sun.UUCP (John Plocher)
Distribution: na
Organization: Sun Microsystems, Mountain View
Lines: 18

In article <11944@grebyn.COM> johnk@opel.UUCP (John Kennedy) writes:
>I've been experiencing a bizarre problem with a Sys V/AT that
>is no longer able to read or write floppies.  Everything works
>fine under MS-DOS, but not under unix.  This is starting to become
>
>At this point, the disk drives and controller cards have been replaced.  I am 
>beginning to suspect something on the mother board, having to do with
>DMA transfers, or some other feature that uport utilizes, that DOS doesn't.

I think you hit it on the head here.  Microport uses DMA for the floppy device,
DOS does not.  One way to test this out is try (under DOS) the fastback install
program.  It tests the DMA chips under a simulated load and will tell you if
the DMA controller is bad.  If it is, hope and pray it is socketted on the
motherboard (and not soldered :-).  Replacing it should solve the problem
(and should cost less than $15.00  - much less than that new 386 motherboard
you were hoping you had an excude to buy :-)

  -John Plocher