[ale] semi [OT] running a robot with linux

[Ron Frazier]

That's pretty cool to have an actual rocket scientist in the group.
Interesting info.  I meant tiny in terms of horsepower, not in terms of
size.

Ron

On Tue, 2011-01-25 at 07:47 -0500, John wrote:
> Space Shuttle GPCs?  What would you like to know? I wouldn't call them 
> "tiny" since they were modified IBM 360 mainframes, there are 5 on-board 
> with at least 3 running and checking each other in a redundant set.  I 
> wrote GN&C code for AP101/S computers for 5 years in HAL/S + about 10 
> other languages that most people have never heard about.
> 
> Those systems each had 108KB of RAM when I started there, but that was 
> upgraded to 256KB.  It wasn't about CPU as much as IO channels - except 
> during guidance calculations. There were thousands of redundant channels 
> for input/output.  I only know about 1 software error that impacted a 
> shuttle mission ... and it was during satellite catch, release, catch, 
> release, catch, release .... tests.  A few months later, a buddy changed 
> that error accumulator from single precision into double precision and 
> forced it to be reset to zero at the beginning of every new guidance 
> calculation. Fairly simple fix. That code hadn't been touched in 15+ 
> years previously.
> 
> Lots of stories from my time at JSC working on shuttle, space station 
> and in the FCRs.
> 
> On 01/24/2011 09:51 PM, Ron Frazier wrote:
> > Hopefully, those computers are powerful ENOUGH.  I think the space
> > shuttle's original computers were similarly tiny.  Sometimes, more
> > complexity breeds more problems.
> >
> > Ron
> 


-- 

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Ron Frazier

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