

Build Your Own NASA Apollo Landing Computer - alexyes
http://www.galaxiki.org/web/main/_blog/all/build-your-own-nasa-apollo-landing-computer-no-kidding.shtml

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waterlesscloud
"It was the first computer to use integrated circuits (ICs), running at 1 Mhz
it offered four 16-bit registers, 4K words of RAM and 32K words of ROM. The
AGC mutlitasking operating system was called the EXEC, it was capable of
executing up to 8 jobs at a time."

And it ran in a little metal can we sent to the moon in the 1960s. Wow.

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l_perrin
There are lots of amazing stories about the AGC:

\- It has a mysterious intruction named EDRUPT ("Ed's interrupt") that took
several years to be reverse engineered afterwards.

\- The 32k ROM was stored on rope memory: bundles of wires with a ferrite core
assembled by hand in factories.

~~~
TheLoneWolfling
EDRUPT does the following:

* Inhibits interrupts until the next RESUME instruction (as if a hardware interrupt had been encountered).

* Loads the Z register into the ZRUPT register. (Incidentally, so far I've seen only a single instance of this instruction, in Luminary 131, and the return address is never used.)

* Takes the next instruction from address 0 (which presumably has been pre-loaded with "TC something").

The instruction also shoves a couple of register values onto the data bus, but
does not save them into memory. My assumption is that some kind of external
instrumentation was able to capture these values, but that they were
irrelevant to normal execution.

Source:
[http://www.ibiblio.org/apollo/assembly_language_manual.html](http://www.ibiblio.org/apollo/assembly_language_manual.html)

Supposedly it was mainly used for self-testing.

