Posted by Scott Johnson on January 19, 2000 at 18:36:02:
In Reply to: why Intel 486? posted by Young Kim on January 19, 2000 at 13:52:45:
> hey.. guys.. my question can be very stupid.. but, I am just wondering.
> why did they replaced Intel 386 with Intel 486?
> aren't there much better processors?
> can anyone answer me as soon as possible?
> Young...
Note that the computer was replaced, not just the processor (this
makes a difference in testing time).
Space is very harsh. The Advanced Computer (which includes a processor
that was based on the Intel 80486 and additional memory) had
to be designed to withstand the rigors of space. It then underwent
extensive tests. Designing and testing products for space applications
can take many years (the amount of time depends on the complexity
of the satellite or instrument). Thus, to answer your question,
yes, there are better processors for your desktop computer, but not
for a space application of this nature.
On a side issue, better processor is relative. You can have a
800 MHz Pentium III and still get the same performance as
a 33 MHz 80486 if you don't have a bus structure that can handle
the higher performing processor. Also, memory can in general
make a bigger difference than processor speed (depending on
what time of work you need to get done). There are a lot
of trade-offs in designing a computer. There are even more
trade-offs if you need to have it operate in harsh environments.
In short, lots of factors had to be considered,
such as existing infrastructure, cost, how long the testing
process will take, and what type of processing needs to get done.
Giving all these factors the Intel-based 80486 was the best
processor.
I hope this helps,
Scott
BTW -
Some of the testing for the 80486 (the advance computer) was done on
the HOST mission in 1998. You can see some of the test results
on the following link
http://hstsci.gsfc.nasa.gov/host/