11 Calculators That Show How Far Computing Has Come in the Past 2,000 Years

I have worked with three of them. I made an Abacus just for the heck of it. The Faber Castell Slide Rule, twin of the one in the video was the mainstay for us doing Chem Engg. Item 7 made by Brunswiga produced two PhDs at IIT Madras. I could really make it spin at almost 500 RPM. I even developed an algorithm to get square roots out of this:

Lot more fun than the aloof smarties that are available now.