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!
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.
I'm pretty sure the bytes are sequentially addressed, but the program (memory contents) may contain branching, conditionals etc to load the next address. Just like assembly language.
If I recall correctly, the microprocessor logic on these missions was RTL (resistor-transistor-logic) which was the predecessor of TTL.
It was sequential but bank-addressed. The AGC had it's own assembly language[1] and was a pretty recognizable general purpose computer[2] for it's time.
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.
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.
My dad was a draftsman, and worked on everything from conveyer belt systems to satellite test rigs. This was in the years before CAD and he often brought A1 and A0 paper home from work for us kids to scribble on.
One time I can remember getting this sheet with this wonderful crossed-grid with rings pattern. I remember staring at it for a good ten minutes before turning it over and trying to draw spider-man ;-)
It was several year before I realised that I was looking at a drawing of core store.
One of my life regrets was that I didn't know to save it. I'd love to have it on the wall framed now ;)
Difference between core memory and rope core memory is that core memory has regular pattern and information is stored in magnetization of the cores, core rope memory on the other hand is read only and information is stored in it's pattern (it's essentially same thing as semiconductor-based ROM, only with little transformers instead of diodes).
I have a 1K x 8 core memory card framed and hanging on the wall with an 8x magnifying glass in front of it. People love to look at it. Then they learn their iPhone has the equivalent of 16 to 32 million of those. Mind-blowing, every time.
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.
32 comments
[ 3.3 ms ] story [ 49.7 ms ] threadhttp://en.wikipedia.org/wiki/Moon_Machines
The original usage of the term LOL.
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.
1: http://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/a...
2: http://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/a...
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! ;)
> 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.
One time I can remember getting this sheet with this wonderful crossed-grid with rings pattern. I remember staring at it for a good ten minutes before turning it over and trying to draw spider-man ;-)
It was several year before I realised that I was looking at a drawing of core store.
One of my life regrets was that I didn't know to save it. I'd love to have it on the wall framed now ;)
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.
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
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?