The Apollo Guidance Computer (AGC) seems quite primitive today but it was a great advance in real time computing for the 1960s. Even with just 2k of RAM and 37k of ROM, the AGC was crucial to the successful operation of the Apollo command modules (CM) and Apollo Lunar Modules (LM).

A team organized by Marc Verdiell (CuriousMarc), who specializes in restoration of vintage electronic devices, is restoring an AGC to working condition. They have recorded their efforts in videos posted on the CuriousMarc channel.

** Apollo AGC Part 1: Restoring the computer that put man on the Moon:

We embark on the restoration of a very rare and historically significant machine: the Apollo Guidance Computer, or AGC. It was the revolutionary MIT-designed computer aboard Apollo that brought man on the Moon (and back!). Mike Stewart, space engineer extraordinaire and living AGC encyclopedia, spearheads this restoration effort. In this first episode, we setup a makeshift lab in his hotel room, somewhere in Houston. The computer belongs to a delightful private collector, Jimmie Loocke, who has generously allowed us to dive in the guts of his precious machine, with the hope of restoring it to full functionality by July 2019, the anniversary of the Apollo 11 Moon Landing.

** Apollo AGC Part 2: Power supplies test

Mike Stewart gives an overview of the hardware. Enamored by the success at checking the IC gates, we proceed to check out and power up the supplies. Once again a long-ish video, but I hesitate to chop it up too much for fear of losing details that might be important to some. Let me know how I am doing.

Apollo AGC Part 3: Main Bus B Undervolt

In preparation for the AGC power up, we test the alarm module B8, simulate the Apollo 13 main bus undervolt, and discover that our memory is faulty. And we find out how much our AGC did originally cost.

Apollo AGC Part 4: We are “go” for power up

The last module has checked out OK. It’s time to attempt powering up the AGC – and see if it awakens from its 43+ years of slumber, even without proper working memory.

Apollo AGC Part 4 ½: Bonus material, full Logic Analyzer trace explanation uncut

Some inquisitive minds requested a non-edited version of the hard core read-back of the LA trace we obtained in episode 4. Your wish is hereby granted. It’s actually quite interesting, provided you are a curious minded enginerd and dedicated follower of this restoration. Normal folks, move right along. Oh, wait, are there any of these left on my channel? Anyhow, I am curious (it’s in my name) to see how popular this video is going to be.

Apollo AGC Part 5: We run a chunk of original Apollo code!

We are out of time for our first visit, and memory is not working. But our whiz kid Mike manages to whip up an FPGA memory emulator for the AGC just before we have to leave. The AGC gets to run a chunk of an original Apollo program!

Apollo AGC Part 6: Restoration update, a new sponsor, and a satellite launch

An update on the work with the DKSY, the rope memory simulator, the core memory, and Mike’s satellite launch!

You can also try out a simulation of the AGC at Online Apollo Guidance Computer Simulator.

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