summary: "Watchdog reset, Instruction Access Exception" message

From: Mico Loretan (
Date: Tue May 25 1993 - 06:23:30 CDT


First, an excerpt from the message I posted yesterday to the group:

> But the problems are back! (Groan) Yesterday, I experienced
> another Openwindows crash, and this evening, the system crashed with this
> message to the console:
> Watchdog reset
> Instruction Access Exception
> Type b (boot), c (continue), or n (new command mode)

Thanks to all who replied! All suggestions point towards a hardware problem;
software problems apparently do not cause this type of disaster. Almost any
hardware problem, it would seem, has the potential to make the watchdogs
bark and howl; but what I'm experiencing may be due to only a limited number
of hardware malfunctions. The candidate culprits are:

  - bad or flaky power supply on system unit (majority of all comments)
  - problems with GX graphics card (or other Sbus cards)
  - bad power supply on the color monitor
  - bad SIMMs
  - overheating of system unit due to blocked vents
  - power fluctuations may induce these problems too

Since I don't have the funds to replace the graphics card, I am hoping
it's one of the other alternatives... For now, I will inquire into the
cost of a new power supply, and how to check out the SIMMs thoroughly.
(While I'm not ruling out power line fluctuations, I'm not sure they're the
most likely culprits in my case, since (i) nobody else in the building I'm in
has been experiencing anything similar and (ii) the problems have tended to
occur even at times when hardly anyone else is in the building, e.g., last
night (Sunday) at 9 p.m. in the evening. -- Is this reasoning correct?)


Mico Loretan

P.S I've gathered all comments into a file, and have named it
    ``watchdog-answers''. There's a lot of useful and quite detailed
    information in there -- like what may set off a watchdog message, etc.
    Scott Gargash's reply is in a separate file, which is named
    ``watchdog-answers-gargash''. He experienced a similar problem,
    some months ago, and posted a query to this group; he collected all
    answers in a file back then, and kindly sent it to me earlier today.
    You may retrieve both files by anonymous ftp from,
    directory ~ftp/pub/watchdog-reset. If you don't have ftp connectivity,
    let me know, and I'll send you copies of the files by email.

Sincere thanks to:

Dale Houston <>
David Sansom <>
Ralf Vandenhouten <>
Birger A. Wathne <>
Doris Harrington <>
Scott Gargash <>
Ron <>
Rick Heaton <>
Dan Franklin <>
Mark Holm <>
Matt <>
Taft Metcalf <positron!metcalf@UUCP-GW.CC.UH.EDU>
Jeff Boyd <BOYDJ@QUCDN.QueensU.CA>
Michael Sullivan <>
Geordie F. Klueber <>
Glenn Satchell <>

Mico Loretan
Assistant Professor
Department of Economics
University of Wisconsin-Madison Tel (608) 262-9890
1180 Observatory Drive Fax (608) 262-4747
Madison, WI 53706-1393 email:

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