When we first saw [DiPDoT’s] homebrew computer, we thought it was an Altair 8800. But no—the machine, while sporting a very familiar front panel, is actually built entirely from relays.
Although it isn’t finished yet, the computer can already perform some simple calculations, as demonstrated in the video below. Interestingly, the Altair-style front panel isn’t just a coincidence. DiPDoT plans to house the device in an Altair-inspired case. This design choice limits him to just two backplane cards, and since he’s running out of space, part of what you see in the video involves him redesigning the backplanes.
We’ll need to watch more of these videos to fully understand how he’s creating his logic gates. A common method is to wire AND gates as series relays and OR gates as parallel relays. However, there are benefits to using relays as two-to-one multiplexers, which can be configured to create any logic gate needed.
If you’re more interested in seeing the computer in action, check out the video around the 14:30 mark where it generates a Fibonacci sequence. The glorious clicking sounds from this beautiful array of electromechanical relays make for quite a nostalgic experience. It’s certainly not a speed demon, but for a computer running on relays, it’s quite impressive.
https://hackaday.com/2025/10/25/relay-computer-knows-the-sequence/
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