Article View: comp.arch
Article #12739Undetectable hardware errors (Was: Speed is the one true performance metric)
From: Dave Lukes
Date: Thu, 20 Nov 1986 09:59
Date: Thu, 20 Nov 1986 09:59
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1561 bytes
Yup, not all hardware errors are catastrophic.
Once, a machine (Burroughs B6700) had a failure in the floating point
output formatting routines (done using clever COBOL-style editing instructions).
All this did was PRINT OUT the wrong answers.
Worse: it was a dual processor, so you got the wrong answer 1/2 the time.
This was extremely nasty, since the program continued using the RIGHT value.
All the calculations were correct, but the answer was wrong!
Most embarrasing: nobody noticed for a while.
All the students kept coming along saying ``My program gets the wrong answer'',
and, of course, who believed them?
On the same subject, unless you have an error correcting RS232 connection,
how do you know that what you see on your screen is correct? (semi :-),
En{j{_oy,
--
Dave Lukes. (...!inset!dave)
``Fox hunting: the unspeakable in pursuit of the uneatable'' -- Oscar Wilde
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!seismo!mcvax!ukc!stc!inset!dave From: dave@inset.UUCP (Dave Lukes) Newsgroups: comp.arch Subject: Undetectable hardware errors (Was: Speed is the one true performance metric) Message-ID: <1105@inset.UUCP> Date: Thu, 20-Nov-86 04:59:23 EST Article-I.D.: inset.1105 Posted: Thu Nov 20 04:59:23 1986 Date-Received: Fri, 21-Nov-86 21:48:06 EST References: <340@euroies.UUCP> <1989@videovax.UUCP> <798@spar.SPAR.SLB.COM> <3576@utcsri.UUCP> <13776@amdcad.UUCP> Reply-To: dave@inset.UUCP (Dave Lukes) Organization: The Instruction Set Ltd., London, UK. Lines: 23