@aral One day I'll have to give a talk about the UI of early mechanical calculators contrasted with modern UI design. These calculators were nothing like modern ones, it was basically a direct front-end to the machinery that made the calculations possible. As a result there was about 3 or 4 families of UI, each distinct (because of patents) and each requiring you study a manual to do even simple calculations. #mechanicalcalculators #calculators #ui #mechanicalcomputers