Re: Would You Fly an Airplane with a Linux-Based Control System?

[snarflemike@yahoo.com (Mike Silva)]

David Botton <david@botton.com> wrote in message news:<2004112218292016807%david@bottoncom>...
> For a real understanding of the Ariane 5 event, see the Ada FAQ:
> 
> http://www.adapower.com/index.php?Command=Class&ClassID=FAQ&CID=328

A small but, I think, important correction.  The hardware at the
center of the failure was apparently built around the Motorola
68020/68881 chips, not the MIL-STD-1750.  The "Operand Error" that
triggered the failure is a hardware exception generated by the FPU
when, among other conditions, a float-to-integer conversion exceeds
the capacity of the integer, exactly as occurred.  The reason this is
important is because it shows that the exception was not generated by
the Ada compiler code but by the hardware, and would therefore have
occurred regardless of the programming language used.  If that's the
case then the "it wouldn't have exploded if it were written in C"
argument evaporates, unless they want to argue that the exception
handler behavior would have been specified differently if the
implementation language was C -- not likely!