The Apollo Guidance Computer

Has anyone been watching Curious Marc’s channel on youtube for the Apollo AGC restoration? He released another segment a few hours ago. This is segment 11. They’re all epic!

He’s got all kinds of vintage hardware restoration videos, including a fascinating series on teletype machines.


Part 12 is now out.

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Part 13. They power up the actual AGC!

Yes, I’ve been following along right from the beginning. :slight_smile: Also highly recommended, the series on the TeleType restoration and the several videos on the HP terminals…

(I’d even had a small e-mail exchange with Marc regarding the printing mechanism of IBM card punches – and he seems to be a really nice guy! Compare – the font editor, admittedly a ridiculous idea, is mostly a reference to Marc and his quest to implement the Star Wars “Aurebesh” alphabet on any machine.)

Yes! I mentioned the teletype restoration in another thread here, I think.

Heck, all of his stuff is amazing. He just visited a telephone museum and it was amazing. The Xerox Alto restoration is amazing. He’s my favorite channel on YT.

Episode 13!

Ferrite cores are remarkable: used in read-write memory, in read-only memory, in amplifiers, and in logic gates, if I have the story straight. There must have been a time when magnetics were very much the thing.

I’m on a pro-audio DIY forum for people who build their own gear, and it took them a while, but they finally created an area called “Magnetics.”

I just put a lot of effort into ordering transformers from England which are exact replicas of the original transformers used in the much fabled Neve recording equipment. I just build a DI box using one of them an an output traffo. They have a sound.

It’s the big blue thing on the bottom that says CARNHILL. They’re heavy, and expensive.

Yeah, magnetics are still hugely important to electronics.

A lot of what gets lumped into the category of “ferrite” is actually powdered iron. Ferrite is a magnetic ceramic. For instance, most of the inductors and transformers in a switching power supply are powdered iron but are often thought to be or called ferrite.

The guys working on this restoration are all amazing engineers. I wonder how much time they’ve put into this already, and how much they would have charged if it was consulting work for a client…

CuriousMarc’s home lab is pretty impressive. In addition to having tons of mint, vintage HP test equipment, he has a lathe and a milling machine.

Episode 14!

… and 14.5!

On the topic of the AGC’s rope memory, I see Ken Shirriff has just posted one of his excellent technical articles:

But while erasable core memory used one core for each bit, core rope stored an incredible 192 bits per core, achieving much higher density

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He did a crap ton of reverse engineering on the core rope emulator.

Don’t miss the 1965 MIT TV program “Computer for Apollo”:

It shows application examples, component testing, as well as the production of the modules, rope memory and back plane at Raytheon. (Personally I found the part on the production of the wiring matrix, which served the purpose of a PCB in the individual modules, pretty interesting. Also that the back plane wiring was actually routed by a computer program.) You also get an idea that this was all set up not for just a few units, but at least a small production run. (And it must have taken quite some test units to get everything going – which explains, why there are quite a few of the units and/or individual modules around.)

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Episode 15!

Part 16.

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Part 17. Carl gets the DSKY hooked up and working. Marc machines custom screws. Some new custom PCBs arrive along with other new hardware, and Ken writes a Hello World, and a Bitcoin mining program. Possibly the first new software for the AGC in 50 years.


Part 18. They find a clever fix for one of the modules that begs the question, why didn’t NASA do it this way in the first place…

Episode 19. Restoration complete! The next episode will be them playing with it.

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