The Whiffletree: A mechanical digital-to-analog converter

150816 Like and subscribe. This is an archive, check the link in the end if you are. Early calculating devices and computers used mechanical digital to
analogue converters. This video describes one based on an arrangement
of metal bars called a "whiffletree" - also sometimes called a
"whippletree." It shows, briefly, the whiffletree used in IBM's
revolutionary selectric typewriter and then illustrates the principles
of a whiffletree converter by showing the simplest one - one that
encodes digital impulses into two bits of information. (This videos is
an appendix to Bill Hammack's video about the operation of the
Selectric Typewriter.)
https://rumblevideoarchive.wordpress.com/