The land before binary

The IRS has a lot of mainframes. And as millions of Americans recently found out, many of them are quite old. So as I wandered about meeting different types of engineers and chatting about their day-to-day blockers I started to learn much more about how these machines worked. It was a fascinating rabbit hole that exposed me to things like "decimal machines" and "2 out of 5 code". It revealed something to me that I had not ever considered:Computers did not always use binary code.Computers did not always use base 2. Computers did not always operate on just an on/off value. There were other things, different things that were tried and eventually abandoned. Some of them predating the advent of electronics itself.Here's a little taste of some of those systems.

I've often wondered why computers are binary to begin with, but it was one of those stray questions that sometimes pops up in your head while you're waiting for your coffee or while driving, only to then rapidly disappear.

I have an answer now, but I don't really understand any of this.