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From: mcferrin@inuxc.UUCP (P McFerrin)
Newsgroups: net.unix,net.unix-wizards
Subject: Re: Machine check, type 0 (VAX 780)
Message-ID: <1162@inuxc.UUCP>
Date: Mon, 2-Sep-85 03:19:26 EDT
Article-I.D.: inuxc.1162
Posted: Mon Sep  2 03:19:26 1985
Date-Received: Wed, 4-Sep-85 04:45:23 EDT
References: <204@drivax.UUCP>
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Xref: watmath net.unix:5549 net.unix-wizards:14681

> Does anyone know what 'Machine check, type 0' is on a VAX 780?
> The message also says 'CP read timeout fault' and prints some
> registers, but I can't find any documentation around here that
> describes things like that. We have goten four of them since
> last Wed.
> 
> We are running 5.2.2 with 4M, one rm03 and one rp07.
> -- 
> 
> Alan Fargusson.
> 
> { ihnp4, amdahl, mot }!drivax!alan

This problem is caused by a device on the Unibus.
It occurrs when a device fails to reply with its vector address when requested
so during a bus-request/bus-grant protocol.  This can be a tough problem
to isolate.  I know of no proceedure to find the culprit except by
replacing one board at a time.

Another cause of this problem can be external wiring to a DR-11 interface
(parallel i/o).  Noise on the request A or B lines can cause the DR11
to withdraw in the middle of a bus-request/bus-grant protocol.

It is a hardware problem.