Software of the Apollo guidance computer was hand-woven into rope core memory

I thought this was interesting (both that the space shuttle still used core memory, and that the challenger memory was retrieved and its contents recovered):

> Core memory is non-volatile storage—it can retain its contents indefinitely without power. It is also relatively unaffected by EMP and radiation. ... For example, the Space Shuttle flight computers initially used core memory, which preserved the contents of memory even through the Challenger's disintegration and subsequent plunge into the sea in 1986.

(From http://en.wikipedia.org/wiki/Magnetic-core_memory#Physical_c... )

Note that this core memory is a little different than the rope core memory described in the linked article.

Interesting. Reminds of the Mayan Quipu system (http://en.wikipedia.org/wiki/Quipu) of storing information in knots in ropes.

I've read somewhere that they even had simple "computers" made out of stone structures that would then have these knot systems inserted into them, but for the life of me I can't remember what these were called.

So the Mayans did it first! ;)

Here's a link to the full video:

http://www.dailymotion.com/video/xxxiij_moon-machines-2008-p...

Around 37 minutes they talk about the alarms on approach and how the dealt with them.

This is from the series Moon Machines, which I cannot recommend highly enough. It's got interviews with the people who worked on Apollo hardware, testing footage I've never seen elsewhere, and some great anecdotes as well. It really gets down into the nitty-gritty design challenges they faced -- it's the Apollo program as the engineers saw it, not the astronauts.

I submitted this a couple years ago but it got no traction then:

http://history.nasa.gov/computers/Part1.html (Computers in Spaceflight: The NASA Experience)

Here's some details on the Apollo guidance computer:

http://history.nasa.gov/computers/Ch2-5.html

Edit: just resubmitted - https://news.ycombinator.com/item?id=7657876

I code at approximately the same rate as the core rope memory weavers wove. I wouldn't trust mine to help people fly to the moon, though. That's incredible!

Here's how to make some - http://www.neazoi.gr/coreROM/index.htm

Very interesting video. I had no idea.

It would have been interesting to see how the program was actually executed. Do the rings around the rope core somehow create a circuit that allows the processor to "know" in which order the 1s and 0s are in? Or is there some kind of mechanical process?

It must have been very easy to make mistakes with all that manual work. I am assuming the weave must have had to have been checked many times.

Using core RAM (not the ROM in the video, but similar) with an Arduino: http://www.corememoryshield.com/report.html

And I thought going through the program, debug, UV erase cycle of a 2716 was torturous!

That's a pretty impressive build tool.

Before there was grunt, before there was maven, before there was make...

Worth including on the the http://en.wikipedia.org/wiki/Build_automation page?

please tell me this was a production build and not used to backup nightly builds.

Rope memory is quite beautiful. Seems like an alien technology - almost organic.

The show that this clip is from is amazing! The Moon Machines. I highly recommend it

I wonder what word they used at that time to distinguish hardware and software bug?

Which television program is that from?

Warning: this video automatically plays.