This is fuckin cool

2 things

• it is a mechanical-digital calculator

• yes, mechanical and digital. Digital being all computation is binary, the values in the gears cannot be between 1 and 2 or 7 and 8 etc, it can only be 1 or 2. The discrete nature makes it digital. He talks about certainty mechanisms like using ball bearings and springs to make sure there are no middle values, etc.