I've just watched this replica of the Antikythera mechanism. I've heard also about Babagge's analytical machine and the Curta calculator. I got curious: What did they use to build computers made of gears? We have nowadays some treatises to make logic gates with transistors, how did they manage to build logic gates or to do whatever was needed for building their computers?
I'm not sure if this question really fits this forum, but it was the nearest one I could think about.