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Apollo 11 computer crashes

 
 
Lawrence D'Oliveiro
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      10-17-2006
If you listen to the transcript of the Apollo 11 moon landing, you'll hear
the phrases "1202 alarm" and "1201 alarm". Those codes indicated that the
Lunar Module onboard computer had run out of memory and rebooted.

The problem was that the crew had left the rendezvous radar on (needed for
leaving the Command Module, and of course for returning to it afterwards),
and the extra processing load was more than the computer could handle.
However, when it was overloaded like this, it was designed to force a
restart, resuming all the already-running tasks from where they left off.
This recovery had been extensively tested on the ground, which was why
Mission Control was confident enough to keep going with the landing.

More details here <http://www.hq.nasa.gov/alsj/a11/a11.1201-pa.html>.
 
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Ron McNulty
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      10-18-2006

Lawrence D'Oliveiro wrote:
> If you listen to the transcript of the Apollo 11 moon landing, you'll hear
> the phrases "1202 alarm" and "1201 alarm". Those codes indicated that the
> Lunar Module onboard computer had run out of memory and rebooted.
>
> The problem was that the crew had left the rendezvous radar on (needed for
> leaving the Command Module, and of course for returning to it afterwards),
> and the extra processing load was more than the computer could handle.
> However, when it was overloaded like this, it was designed to force a
> restart, resuming all the already-running tasks from where they left off.
> This recovery had been extensively tested on the ground, which was why
> Mission Control was confident enough to keep going with the landing.
>
> More details here <http://www.hq.nasa.gov/alsj/a11/a11.1201-pa.html>.
>From your link:

<...long before Bill Gates, we had developed a real-time multi-tasking
operating system...>
I was not aware Microsoft had yet developed a RTOS?? What is it
called??

We have to remember they were using military-grade RTL technology -
outdated even in 1967. They did a near-impossible job, and did it
extremely well.

Regards

Ron
(an ex real-time programmer)

 
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Lawrence D'Oliveiro
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      10-18-2006
In message <(E-Mail Removed) .com>, Ron
McNulty wrote:

> We have to remember they were using military-grade RTL technology -
> outdated even in 1967.


NASA has a long tradition of using outdated technology on manned spacecraft.
I think it's deliberate--to do with the fact that human lives are at stake,
so they want stuff that's unlikely to have new, undiscovered bugs in it.

> They did a near-impossible job, and did it extremely well.


I can't help feeling they were lucky in some ways. They _did_ lose at least
6 astronauts, and 6 others were lucky to escape with their lives.

It's been pointed out that, with all the extra safeguards that keep getting
put in, the Shuttle flights are now costing as much as the Apollo ones did.
But then, if Apollo had been kept going through more than 200 flights, it
might have had a lot more fatal accidents than the Shuttle has.
 
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Don Hills
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      10-18-2006
In article <eh4veu$c4t$(E-Mail Removed)>,
Lawrence D'Oliveiro <(E-Mail Removed)_zealand> wrote:
>
>NASA has a long tradition of using outdated technology on manned spacecraft.
>I think it's deliberate--to do with the fact that human lives are at stake,
>so they want stuff that's unlikely to have new, undiscovered bugs in it.


.... and is proven rugged in high-radiation environments. Last time I looked
(a couple of years ago), the ISS was using 10base-2 (coax cable) for its
internal Ethernet network, and IBM Thinkpad laptops with 486 CPUs.

--
Don Hills (dmhills at attglobaldotnet) Wellington, New Zealand
"New interface closely resembles Presentation Manager,
preparing you for the wonders of OS/2!"
-- Advertisement on the box for Microsoft Windows 2.11 for 286
 
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Lawrence D'Oliveiro
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      10-19-2006
In message <(E-Mail Removed)>, Don Hills wrote:

> In article <eh4veu$c4t$(E-Mail Removed)>,
> Lawrence D'Oliveiro <(E-Mail Removed)_zealand> wrote:
>>
>>NASA has a long tradition of using outdated technology on manned
>>spacecraft. I think it's deliberate--to do with the fact that human lives
>>are at stake, so they want stuff that's unlikely to have new, undiscovered
>>bugs in it.

>
> ... and is proven rugged in high-radiation environments. Last time I
> looked (a couple of years ago), the ISS was using 10base-2 (coax cable)
> for its internal Ethernet network...


Why would that be more radiation-hard than UTP?

> ... and IBM Thinkpad laptops with 486 CPUs.


486s? For which systems? Because I remember reading an article from several
years ago that said the life-support systems were built on 80386 CPUs
programmed in Ada. They had plenty of grunt for the job, since they were
most emphatically not running anything resembling Microsoft Windows.
 
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Don Hills
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      10-19-2006
In article <eh6lk7$cr5$(E-Mail Removed)>,
Lawrence D'Oliveiro <(E-Mail Removed)_zealand> wrote:
>
>Why would that be more radiation-hard than UTP?


Maybe more EMI resistant in this particular environment. Maybe simply
because it was known to work reliably in space, whereas UTP hasn't yet been
proven reliable (but may well work fine)? I don't know.

>486s? For which systems? Because I remember reading an article from several
>years ago that said the life-support systems were built on 80386 CPUs
>programmed in Ada. They had plenty of grunt for the job, since they were
>most emphatically not running anything resembling Microsoft Windows.


The laptops were for general purpose computing - payload support, records
keeping, report writing, email etc. I would hope that life support systems
would be built to a higher reliability requirement than a laptop and built
into an equipment rack.

My sources were some presentations I saw while working at IBM, and more
recently an online article about the ISS which contained some photos. One,
allegedly showing one of the astronauts "fixing a computer problem", was
high enough resolution to show the actual Thinkpad model (760 if I recall
correctly), the network connection (PCMCIA with 10base2 dongle) and even
what was on the screen (a text mode BIOS setup tool in use).

I decided to see if I could find the picture again using Google Image
search. I didn't, but I did find this:

www.spaceref.com/iss/computer/

Lots of good stuff. Thinkpad 760XD? That's a Pentium 166 system, not a 486.
Ah, I see where I got confused: the standard Space Shuttle laptop was a
755CD (486-75). The 760XD replaced them in the shuttle and are also used in
the Station.

One of the technical PDFs on the aforementioned page confirms the network
cabling is 10base2. Apparently there's also an RF LAN capability.

I would imagine that qualification testing is aleady underway on more modern
systems, if they're not already in place. After all, the 760 systems were
running Windows 95 and Microsoft has dropped support for it...

I didn't poke around much, but there appears to be a lot of stuff on
www.nasa.gov and other sites as well.

--
Don Hills (dmhills at attglobaldotnet) Wellington, New Zealand
"New interface closely resembles Presentation Manager,
preparing you for the wonders of OS/2!"
-- Advertisement on the box for Microsoft Windows 2.11 for 286
 
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Dave Taylor
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      10-21-2006
Lawrence D'Oliveiro <(E-Mail Removed)_zealand> wrote in news:eh6lk7
$cr5$(E-Mail Removed):

> Why would that be more radiation-hard than UTP?


Because of the shield braid. The U in UTP stands for? Yes that's right,
Unshielded.

--
Ciao, Dave
 
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Lawrence D'Oliveiro
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      10-21-2006
In message <Xns98638B7819CBEdaveytaynospamplshot@203.97.37.6> , Dave Taylor
wrote:

> Lawrence D'Oliveiro <(E-Mail Removed)_zealand> wrote in
> news:eh6lk7 $cr5$(E-Mail Removed):
>
>> Why would that be more radiation-hard than UTP?

>
> Because of the shield braid. The U in UTP stands for? Yes that's right,
> Unshielded.


Is copper impervious to gamma rays?
 
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