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From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: Ariane 5 failure
Date: 1996/10/02
Message-ID: <EACHUS.96Oct2153555@spectre.mitre.org>#1/1
X-Deja-AN: 186754974
references: <96100111162774@psavax.pwfl.com>
organization: The Mitre Corp., Bedford, MA.
newsgroups: comp.lang.ada
Date: 1996-10-02T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <96100111162774@psavax.pwfl.com> "Marin David Condic, 407.796.8997, M/S 731-93" <condicma@PWFL.COM> writes:

   Marin David Condic

   > It's not a case of saving a few CPU cycles so you can run Space
   > Invaders in the background. Quite often (and in particular in
   > *space* systems which are limited to rather antiquated
   > processors) the decision is to a) remove the runtime checks from
   > the compiled image and run with the possible risk of undetected
   > constraint errors, etc. or b) give up and go home because there's
   > no way you are going to squeeze the necessary logic into the box
   > you've got with all the checks turned on.

   > It's not as if we take these decisions lightly and are just being
   > stingy with CPU cycles so we can save them up for our old age. We
   > remove the checks typically because there's no other choice.

   In this case though, management threw out the baby with the
bathwater.  To preserve a 20% margin in the presence of a kludge
already known to be applicable only to the Ariane 4, they took out
checks that would be vital if the kludge ran on the Ariane 5, then
forgot to take the kludge out.

   The proper solution was to recognize in the performance specs that
the load was 81% or whatever until the intertial alignment software
shut down after launch.


--

					Robert I. Eachus

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