NASA Open Sources Apollo 11 Code (2009) • Hacker News Board

Re: NASA Open Sources Apollo 11 Code (2009)

#31

Post by ChuckMcM » Thu, Apr 03, 2014, 5:27 PM UTC

Given the pocket calculator joke[1] I'm wondering if anyone has built functionally equivalent AGC code on a more modern processor? And by functionally equivalent I mean a black box tester with an Apollo AGC would not be able to tell if it was running the old code or the new code.

[1] "It’s been famously remarked that the on-board systems in Apollo 11 had less computing power than a modern pocket calculator." -- http://apcmag.com/apollo-11-code-goes-open-source.htm

Re: NASA Open Sources Apollo 11 Code (2009)

#32

Post by Implicated » Thu, Apr 03, 2014, 5:38 PM UTC

Yes it's a 2009 blog post, but I still found it new and interesting.

Especially the "# TEMPORARY, I HOPE HOPE HOPE" comments, so I decided to look into them and hopefully find someone who has a clue to explain...which I did, here's a link for anyone else interested...

(last comment) http://www.metafilter.com/83450/Apollo-11-Source-Code

Re: NASA Open Sources Apollo 11 Code (2009)

#33

Post by talmand » Thu, Apr 03, 2014, 6:08 PM UTC

NAFV_P wrote: post #27

spectre256 wrote: post #6

It's worth noting that the software, while only 36k machine words long, and the hardware, which was very slow even by the standards of other computers of the 60s, were remarkable works created in only a couple years by huge teams (peak of 800 people working on hardware and 400 on software IIRC). Its popular to dismiss the AGC as simple and uninteresting, but it was a challenging engineering task, and it never once ha…

> Its popular to dismiss the AGC as simple and uninteresting, but it was a challenging engineering task, and it never once had a failure in flight. Stating it never failed in flight is jumping the gun a bit, it didn't fly enough times to get a reliable statistic.

I would think it's accurate to state that the system never had a failure in flight if it never had a failure in flight, despite how many times it flew.

If you were to compare it to something else, then how many times it flew becomes important. For example, you can't necessarily say that a 100% success rate over 5 attempts is better than a 95% success rate over 100 attempts.

Re: NASA Open Sources Apollo 11 Code (2009)

#34

Post by talmand » Thu, Apr 03, 2014, 6:20 PM UTC

If anyone compiles this; remember to set your turbo button to off or the timings will be wildly inaccurate.

Re: NASA Open Sources Apollo 11 Code (2009)

#35

Post by pearjuice » Thu, Apr 03, 2014, 6:35 PM UTC

Google Code? That still a thing? It must be enterprise-government-class contracts like this keeping it alive.

It would have been much cooler to see it on Github and people forking away at it.

Re: NASA Open Sources Apollo 11 Code (2009)

#36

Post by meandthebean » Thu, Apr 03, 2014, 6:41 PM UTC

Trashy Little Subroutines is going to be my new band's name.

https://code.google.com/p/virtualagc/source/browse/trunk/Lum...

Re: NASA Open Sources Apollo 11 Code (2009)

#37

Post by spectre256 » Thu, Apr 03, 2014, 9:03 PM UTC

talmand wrote: post #33

NAFV_P wrote: post #27

Earlier quoted context omitted.

> Its popular to dismiss the AGC as simple and uninteresting, but it was a challenging engineering task, and it never once had a failure in flight. Stating it never failed in flight is jumping the gun a bit, it didn't fly enough times to get a reliable statistic.

I would think it's accurate to state that the system never had a failure in flight if it never had a failure in flight, despite how many times it flew. If you were to compare it to something else, then how many times it flew becomes important. For example, you can't necessarily say that a 100% success rate over 5 attempts is better than a 95% success rate over 100 attempts.

Right. I think I remember Digital Apollo quoting an engineer who estimated, based on their extensive ground testing, that the AGC had a MTBF of about 50,000 hours. That's not particularly good, but considering all the Apollo missions spent only about 1000 hours in space total, it was apparently good enough.