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From: KK6GM <mjsilva@scriptoriumdesigns.com>
Subject: Re: How would Ariane 5 have behaved if overflow checking were not turned off?
Date: Tue, 15 Mar 2011 12:45:56 -0700 (PDT)
Date: 2011-03-15T12:45:56-07:00	[thread overview]
Message-ID: <36eecd5e-52fe-4a23-8cbe-7e124c71846d@i39g2000prd.googlegroups.com> (raw)
In-Reply-To: 87ipvk6vva.fsf@mid.deneb.enyo.de

On Mar 15, 12:12 pm, Florian Weimer <f...@deneb.enyo.de> wrote:
> * Stephen Leake:
>
> > Elias Salom o Helou Neto <eshn...@gmail.com> writes:
>
> >> I have followed the (quite lenghty) on a topic, IIRC, about bitwise
> >> operators, which eventually lead to people mentioning the Ariane 5
> >> case.
>
> >> Since then I have been wondering. If compiler checking where actually
> >> turned on, what would have happened? How could it avoid the disaster?
>
> > Just to remind people; the real problem was that Ariane 4 code was
> > reused on Ariane 5, without carefully considering the design, also
> > without adequate testing.
>
> It's odd that after all those years, little hard data is available on
> the defect.  The published report uses terminology which is a slightly
> bit off in the Ada context, so it led only to further speculation.
> There is alleged source code floating around, but it is an obvious
> fabrication by someone who is not an Ada programmer (there are syntax
> errors).

The Ariane computers were based on the MC68020 with MC68882 FPU.
"Operand Error", as mentioned in the report, is apparently an FPU
error, generated when, among other reasons, a floating point to
integer conversion is attempted and the value will not fit into the
integer.  That's exactly what happened in the Ariane 501.

Since the error was apparently a hardware (FPU) trap, that makes it
even harder to claim that it was somehow Ada's fault, since presumably
all error traps generated by the hardware would have been handled the
same regardless of the language.



  reply	other threads:[~2011-03-15 19:45 UTC|newest]

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-14 15:49 How would Ariane 5 have behaved if overflow checking were not turned off? Elias Salomão Helou Neto
2011-03-14 16:17 ` KK6GM
2011-03-14 19:25   ` Yannick Duchêne (Hibou57)
2011-03-14 19:28     ` Vinzent Hoefler
2011-03-14 20:28     ` KK6GM
2011-03-15  4:02       ` Yannick Duchêne (Hibou57)
2011-03-15  4:53         ` Shark8
2011-03-14 18:29 ` Vinzent Hoefler
2011-03-16 10:41   ` How would Ariane 5 have behaved if overflow checking were notturned off? robin
2011-03-16 15:16     ` Simon Wright
2011-03-17 11:48       ` robin
2011-03-16 16:58     ` Martin Krischik
2011-03-16 23:39       ` How would Ariane 5 have behaved if overflow checking werenotturned off? robin
2011-03-17 18:48         ` Vinzent Hoefler
2011-03-18 12:06         ` Alex R. Mosteo
2011-03-18 21:15           ` How would Ariane 5 have behaved if overflow checking were not turned off? robin
2011-03-20 10:42             ` Vinzent Hoefler
2011-03-20 17:06         ` How would Ariane 5 have behaved if overflow checking werenotturned off? Martin Krischik
2011-03-20 17:11         ` Martin Krischik
2011-03-20 18:10           ` Dmitry A. Kazakov
2011-03-21 13:24         ` Leif Roar Moldskred
2011-03-20 13:07       ` How would Ariane 5 have behaved if overflow checking were notturned off? Florian Weimer
2011-03-20 17:00         ` Martin Krischik
2011-03-20 20:17           ` Florian Weimer
2011-03-20 20:37             ` Vinzent Hoefler
2011-03-20 20:14         ` Vinzent Hoefler
2011-03-16 18:20     ` Vinzent Hoefler
2011-03-16 18:29       ` Hyman Rosen
2011-03-16 18:55         ` Vinzent Hoefler
2011-03-16 19:40         ` KK6GM
2011-03-16 20:52           ` Hyman Rosen
2011-03-16 21:02             ` KK6GM
2011-03-16 21:09             ` Shark8
2011-03-16 21:13               ` Hyman Rosen
2011-03-16 21:35                 ` Shark8
2011-03-16 22:27             ` Vinzent Hoefler
2011-03-16 21:04           ` Shark8
2011-03-16 21:10             ` Hyman Rosen
2011-03-16 21:27               ` KK6GM
2011-03-16 21:31               ` Shark8
2011-03-16 22:32               ` Vinzent Hoefler
2011-03-18 21:14           ` How would Ariane 5 have behaved if overflow checking were not turned off? robin
2011-03-16 23:46       ` How would Ariane 5 have behaved if overflow checking werenotturned off? robin
2011-03-17  0:26         ` Simon Wright
2011-03-17 11:01           ` Georg Bauhaus
2011-03-17 11:04           ` robin
2011-03-17 13:36             ` Niklas Holsti
2011-03-18 21:13               ` How would Ariane 5 have behaved if overflow checking were not turned off? robin
2011-03-19 10:12                 ` Niklas Holsti
2011-03-17 22:51         ` How would Ariane 5 have behaved if overflow checking werenotturned off? Vinzent Hoefler
2011-03-18 21:13           ` How would Ariane 5 have behaved if overflow checking were not turned off? robin
2011-03-20 10:42             ` Vinzent Hoefler
2011-03-15  6:28 ` Stephen Leake
2011-03-15 17:32   ` Keith Thompson
2011-03-15 17:40     ` KK6GM
2011-03-15 19:44     ` Robert A Duff
2011-03-15 19:12   ` Florian Weimer
2011-03-15 19:45     ` KK6GM [this message]
2011-03-15 19:57     ` Vinzent Hoefler
2011-03-20 13:00       ` Florian Weimer
2011-03-20 20:13         ` Vinzent Hoefler
2011-03-15 19:42   ` John B. Matthews
2011-03-17 11:44   ` robin
2011-03-17 18:37     ` Vinzent Hoefler
2011-03-17 23:04       ` How would Ariane 5 have behaved if overflow checking were notturned off? robin
2011-03-18 15:55         ` Vinzent Hoefler
2011-03-17 21:37     ` How would Ariane 5 have behaved if overflow checking were not turned off? Vinzent Hoefler
2011-03-16 10:33 ` robin
2011-03-16 15:08   ` Simon Wright
2011-03-17 12:39     ` robin
2011-03-17 13:41       ` Georg Bauhaus
2011-03-17 23:34         ` How would Ariane 5 have behaved if overflow checking were notturned off? robin
2011-03-18 12:57           ` Hyman Rosen
2011-03-18 16:49             ` KK6GM
2011-03-18 17:18               ` Dmitry A. Kazakov
2011-03-19 17:55                 ` Keith Thompson
2011-03-20 18:39                   ` Robert A Duff
2011-03-17 18:43       ` How would Ariane 5 have behaved if overflow checking were not turned off? Vinzent Hoefler
2011-03-17 20:58       ` Simon Wright
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