How the Selectric's digital-to-analogue converter worked

This great video explainer shows the inner workings of a digital-to-analogue converter, using the IBM Selectric's early example of the form to illustrate the mechanism:

Using slow motion video Bill Hammack, the engineer guy, shows how IBM's revolutionary "golf ball" typewriter works. He describes the marvelous completely mechanical digital-to-analogue converter that translates the discrete impulse of the keys to the rotation of the type element.

IBM Selectric Typewriter & its digital to analogue converter (Thanks, Fipi Lele!)