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From: howard@cos.UUCP
Newsgroups: comp.misc
Subject: Re:  What the world needs now [is an exploding computer]
Message-ID: <312@cos.COM>
Date: Thu, 4-Jun-87 09:44:18 EDT
Article-I.D.: cos.312
Posted: Thu Jun  4 09:44:18 1987
Date-Received: Sat, 6-Jun-87 07:22:25 EDT
Organization: Corporation for Open Systems, McLean, VA
Lines: 26
Keywords: Tape drives, external influences

A variant I personally experienced had to do with making computers
(or more specifically tape drives) die temporarily due to external 
events.

In the late '70's, I worked at the Library of Congress.  We had
IBM and Amdahl mainframes with STC tape drives as our main data base
machines.  Given the role of the world's largest library, our computer
room received considerable attention.

The British Broadcasting Corporation was given access to much of 
the Library, to film a documentary.  We found that some major system
crashes began to happen when they were in the computer room.  We 
thought it might be their video equipment, floods, etc., but could
not find the cause.

The symptom was clear:  periodically, ALL of our tape drives would
simultaneously stop, rewind, and unload, no matter what they were
doing.  The operating system could not deal with such simultaneous
events, and would crash.

It turned out to be an intermittent event:  most BBC work was film
or video, but they occasionally took still photographs.  When their
electronic flash pointed at the front of the tape drives, the short
burst of light was reflected into the photoelectric end-of-tape
sensors of each tape drive, causing EVERYTHING to simultaneously
sense (erroneously) end-of-tape.