Re: computer language used to program Mars Lander

[Nick Keighley <nick_keighley_nospam@hotmail.com>]

On 14 Jul, 12:18, "jhc0...@gmail.com" <jhc0...@gmail.com> wrote:
> Interesting article I came across on Slashdot:
>
> http://developers.slashdot.org/developers/08/07/10/213211.shtml
>
> They are using C at JPL to program Mars Lander and just about
> everything now! Not Ada. Anyone got an explanation? I wonder also, do
> they really mean C++ when they say C. In my experience, this is a
> frequent, although disagreeable usage.

contrary to popular expectations space probes are very
conservative in their use of technolgy. Processors are old
(and hence proven) memorys are small (less vulnerable to radiation).

Rememeber if there's a bug they can't just upgrade the software.
Well they can but it has to be mostly working for the download
to work.

These are essetially embedded systems and C is still popular
in that world.

I suspect its a damn sight easier to prove C correct than C++.

    a = b + c;

probably does what it says in C (assuming b and c have good values
and it doesn't overflow). In C++ there could be half a dozen
overloaded
operators in there.

--
Nick Keighley

I know not what I appear to the world, but to myself I seem to have
been
only like a boy playing on the sea-shore, and diverting myself in now
and
then finding a smoother pebble or a prettier shell, whilest the great
ocean of truth lay all undiscovered before me.
                    (Sir Issac Newton)