Comment by bcoates

I love that film, but it's kind of weird that it doesn't mention what's probably the most important invention that makes this type of computer possible: The torque amplifier.

All the devices shown suffer power losses between input and output, some of them severe. A torque amplifier has two shafts that are 1:1 geared for speed but the output shaft has extra power taken from a third supply shaft, like the supply to a logic gate that lets it drive more output power than it draws from its inputs.

https://en.wikipedia.org/wiki/Torque_amplifier