Show HN: Minivac 601 Simulator - a 1961 Relay Computer https://ift.tt/cU71d0T

Show HN: Minivac 601 Simulator - a 1961 Relay Computer Hey HN! I'm very proud of sharing this project with you all, after ~2 years of starts and stops, and about 5 different attempts at making it. Context/history: In 1961, the Minivac 601 [0], an educational electronics kit - somewhat similar to those "300 circuits in one" you may have had growing up as I did - was created by none other than Claude Shannon. The Minivac is disarmingly simple: it consists roughly speaking of 6 relays, 12 lights, 6 buttons, and a motorized wheel. You'd think that it couldn't really do much. Well, amazingly, it can do a lot. You can wire up the components in a way that will make the Minivac play tic-tac-toe, or OCR-detect 10 digits... The sample "demo" circuit I chose for the homepage shows a binary counter that counts up to 7. Another amazing thing about the Minivac is definitely its manuals [1]. Their spirit is what I hope to capture in the coming (years?) as I keep improving this project. The manuals are generous and well-written and are not only an amazing gradual introduction to relay-based logic - they touch on computing at large. With amazing 1960s graphics/cartoons, of course. That's probably what got me to work on the Minivac. I learned about the device a bit before going to the Recurse Center, fell in love with the manuals, and was frustrated that I couldn't try out the circuits or play around with the device! I thought that creating a JavaScript-based emulator would be an "easy" way to get there. Turns out that correctly simulating electricity isn't "easy". :-) But I'm very proud that it now seems to be doing the right thing for most circuits that I've tested from the book. Yes, this Minivac Simulator has a TypeScript testing suite! Looking forward to hearing from you all. Cheers [0] https://ift.tt/AXqr06G [1] https://ift.tt/MhAg4qZ... Repo: https://ift.tt/APzVBaX https://ift.tt/od0txWf November 16, 2025 at 10:24PM