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I built a relay computer for a science fair in the 60's. The power supply was from a pinball machine. The relays were mercury-sealed, from an aircraft. It had

I built a relay computer for a science fair in the 60's. The power supply was from a pinball machine. The relays were mercury-sealed, from an aircraft. It had seven words of five bits each (that's all the relays we had). It could add, subtract and store results. We got honourable mention.

Animats 9y ago
I did that, too.[1] 10 words of 7 bits, addressed with a Strowger switch. Add, subtract, shift, branch, conditional branch, so it was Turing-complete. The "paper tape" reader had so much drag I had to use vinyl seat-cover material for tape. [1] http://www.animats.com/nagle/myfirstcomputer.html http://www.animats.com/nagle/myfirstcomputer.html
- cr0sh 9y ago
  This is amazing - thank you for posting about it! BTW - how old were you (if you care to tell the world!) when you created this machine? What made you take pictures of it? Did you keep any part of it, or was it all relegated to the "junk bin"? I have found that it is extremely rare that these machines like yours ever have pictures, much less the writeup like you have created. It doesn't appear many people created such computers back then, and I don't know of any who published how they created them. For instance, I have yet to see any old "Popular Mechanix" style article from the 1960s on "Build Your Own Electronic Brain" (as I would imagine it would be titled) - but such an electro-mechanical project would certainly fit those kind of pulp magazines. Which I find odd. I don't know why these machines - few as they were - were never publicized; perhaps there wasn't an audience, or because there were so few, those with the ability to write such an article were fewer? I do know there was some interest in computing at a "lay-person's" level, because there were several books on contemporary forms of computing and programming available in the 1960s (most had enough information to allow a person with sufficient skills and knowledge to design and build a simple machine - perhaps you got inspiration from such a source for yours?). These early "hobbyist" computers, along with early hobbyist robots - represent the very earliest dawn building toward the microcomputer revolution of the later 1970s - but the vast majority, if not all of them, are lost to time, unfortunately.

Animats 9y ago

I did that, too.[1] 10 words of 7 bits, addressed with a Strowger switch. Add, subtract, shift, branch, conditional branch, so it was Turing-complete. The "paper tape" reader had so much drag I had to use vinyl seat-cover material for tape. [1] http://www.animats.com/nagle/myfirstcomputer.html http://www.animats.com/nagle/myfirstcomputer.html

cr0sh 9y ago
This is amazing - thank you for posting about it! BTW - how old were you (if you care to tell the world!) when you created this machine? What made you take pictures of it? Did you keep any part of it, or was it all relegated to the "junk bin"? I have found that it is extremely rare that these machines like yours ever have pictures, much less the writeup like you have created. It doesn't appear many people created such computers back then, and I don't know of any who published how they created them. For instance, I have yet to see any old "Popular Mechanix" style article from the 1960s on "Build Your Own Electronic Brain" (as I would imagine it would be titled) - but such an electro-mechanical project would certainly fit those kind of pulp magazines. Which I find odd. I don't know why these machines - few as they were - were never publicized; perhaps there wasn't an audience, or because there were so few, those with the ability to write such an article were fewer? I do know there was some interest in computing at a "lay-person's" level, because there were several books on contemporary forms of computing and programming available in the 1960s (most had enough information to allow a person with sufficient skills and knowledge to design and build a simple machine - perhaps you got inspiration from such a source for yours?). These early "hobbyist" computers, along with early hobbyist robots - represent the very earliest dawn building toward the microcomputer revolution of the later 1970s - but the vast majority, if not all of them, are lost to time, unfortunately.