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Mon, 28 Jul 1997 09:30:42 PST8
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     According to the Peter Coffee's July 21 PC Week column, NASA chose to
     use a beta version of VxWorks with the R6000.  As a result, they had
     problems with stack management and pointers during task switching
     which is most likely why the machine has continually rebooted itself
     when too many tasks were going in parallel.  They got what the paid
     for with COTS in this instance.

     Darren Davenport


______________________________ Reply Separator _________________________________
Subject: Re: Ada goes to Mars (maybe)
Author:  "Panfil, Thomas A." <[log in to unmask]> at CCGATE
Date:    7/24/97 4:57 PM


I think that our friend from JPL simplified the hardware description to
put it into a commonly known context.  I suspect that the processor he
really considers using is the RAD6000 which is currently in use on the
ongoing exploration by the "Mars Pathfinder Mission."

Per a 14 July 1997 Federal Computer Week article entitled "COTS in Space":

".....

One of the main components of the mission is the on-board processor
that guided the Pathfinder Lander's journey to Mars, controlled its
landing, and now governs its operation from the planet's surface.
The processor, a radiation-hardened version of IBM Corp.'s 32 bit-RISC
System/6000, was adapted for the mission by Lockheed Martin Federal
Systems in Manassas, VA.

The chip is the first radiation-hardened commercial processor to guide
a NASA mission.  The RAD6000, as it was renamed by Lockheed, was
responsible for crucial elements of the flight to Mars such as cruise
altitude control.  The chip also managed the lander's entry events,
including deploying the parachutes and air bags that cushioned the
Lander's fall to Mars.

.....

Despite its radiation-hardened state, the commercial version of the
processor provides the Pathfinder mission with 22 MIPS of processing
power.  The RAD6000 can provide an unprecedented space throughput of
up to 35 MIPS, ...

In addition to the processor, the flight computer contains a sealed
memory unit that also uses off-the-shelf technology, with tweaks to
allow it to survive the energy particles.  Although the mission required
128M of dynamic RAM, this type of memory space is not available in the
hardened state, ...  The processor's memory unit detects any damage
done by the particles and heals itself through a special error
correction process.

....."


News reports typically seem to have some garbles, and can't provide all
details.  This one doesn't mention the bus or the OS used, but some
IBM RISC System/6000 machines are called "PowerPCs".



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 / __   _   _   _  \[]|/   Ada95    | |Ada|  |83 |        |  C++  |
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 //o^o \_/ \_/ \_/ o^o  o^o^o  o^o^o   o^o    o^o        o^o     o^o
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                           Thomas A. Panfil
          Secretary & Treasurer -- Baltimore SIGAda
                  (301) 498-7313

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