





Restoring the Apollo Guidance Computer: Lessons from a 50-year-old system The Apollo Guidance Computer (AGC) played a critical role in the Moon landings. One of the first computers to use integrated circuits, the compact AGC provided guidance, navigation, and control onboard the spacecraft. This talk explains how we repaired an AGC (including its ferrite core memory), got it running, and ran the original Moon landing software on it. I'll also discuss the AGC's innovations in software engineering, user interfaces, interpreters, real-time computing, and multi-tasking, along with its performance mining Bitcoins. Bio: Ken Shirriff restores old computers, including a Xerox Alto and an IBM 1401 punch card computer. His blog (righto.com) discusses reverse engineering everything from chargers to microprocessors. He wrote the Arduino IRremote library and added seven characters to Unicode. Ken was formerly a programmer at Google and holds a Ph.D. in computer science from UC Berkeley. Organizer note: The silver lining of the Covid-19 pandemic is that we can bring in speakers from all over, not just in the Seattle area. This presentation by Ken Shirriff would not have been possible otherwise. Having followed Ken’s blog for some time I and thrilled that he is able to join us from Silicon Valley via Zoom for this presentation. Ken’s bio doesn’t begin to do justice to the level of effort involved in reverse engineering and restoring the Apollo systems and many other devices. His blog is both entertaining and informative. Just understanding how the moon landing was accomplished with so little computing horsepower is one thing, actually making the computer work and then mining Bitcoin on it is something else entirely. Ken assures me that he will leave lots of time for questions.