> Date: Sat, 28 Feb 2004 20:03:51 +0000
> From: Clive Page <[log in to unmask]>
> On Fri, 27 Feb 2004, Richard Maine wrote:
>
> > > ADA still being seriously used?
> >
> > Yes. Very much so. Mostly in a pretty limited application domain...
>
> Indeed. You may recall the failure of ESA's first Ariane-5 rocket: the
> failure to handle an overflow exception properly in ADA
"properly"? It wasn't handled at all.
The exception was treated as if a hardware error had occurred,
and the computer was shut down.
The exception arose because the team assumed that overflow
would not occur during a conversion from 64-bit float to 16-bit integer.
The team therefore did not include a software test for this
data conversion and source of potential overflow.
It was a programming error of of monumental prooportions,
because any exception of any kind would result in shutdown
of the computer (including the backup).
They knew this, but failed to include a software check.
> was one of the
> chain of mistakes which caused the rocket to blow up. (If you want to see
> the report on the failure, search Google for "Ariane 501 report" and the
> second item has it.)
>
> --
> Clive Page,
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