w_tom wrote:
> Sebastian Gottschalk wrote:
> > OK, and why should spacecraft designers care for computers that are only
> > used on earth's ground?
>
> Again, the word is reliability. Designs must be functionally well
> proven AND use parts that are 'fully qualified'. Speed of computer
> chip is not as important as design been well proven AND money already
> spent to have a part 'fully qualified'.
>

Oh, so it would cost too much then to have a fast processor built and
"fully
qualified"?

> Any complicated computations are better performed on earth.
>
> Again, electronics for different environments - space, military, or
> retail - have different parameters. Furthermore, most all electronics
> is redundant. Function of an IC for military or aerospace is more
> often a same function found previously in retail products. IC
> certified for harsh environments may take many years to eventually be
> 'fully qualified'. By that time, hardware is considered obsolete in a
> retail marketplace.
>
> Meanwhile, a legacy from retail designs (ie hardware that is not
> harmed by software) is later incorporated in those 'harsh environment'
> designs. 'High tech' contains mostly legacy designs with a few
> innovations. If a completely new design is defective (if software can
> harm the hardware), then the concept called legacy corrects that
> problem and verifies it does not happen again. Then hardware is ready
> for other environments. Again, the word is reliability.