If you are interested in non-electronic digital computers you might want to check out this previous discussion:(<a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=7824588" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=7824588</a>)<p>If you are particularly interested in domino logic and adders, 	baddox posted this video (<a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=SudixyugiX4" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=SudixyugiX4</a>), 	
petercooper posted this one (<a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=lNuPy-r1GuQ" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=lNuPy-r1GuQ</a>) by Matt Parker (the same guy in this video) and I documented a 2-bit build I did (<a href="http:&#x2F;&#x2F;imgur.com&#x2F;a&#x2F;qq7Kl" rel="nofollow">http:&#x2F;&#x2F;imgur.com&#x2F;a&#x2F;qq7Kl</a>).