[averros]

Of course, people DID build ternary computers.

The most notable of these is Setun' (I had a chance to play with it at Moscow State University).

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

[haqreu]

Setun is the only example, and it had a binary memory.

[shakna]

There was also the Canadian QTC-1. [0]

[0] https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=2009020829793...

[haqreu]

This is ROM only, not a fully functioning computer.

[shakna]

Head to the end of the paper about the ROM [0], and you'll find the QTC-1 was the computer said ROM was designed for, not the ROM design itself.

[0] https://wwwee.ee.bgu.ac.il/~kushnero/ternary/Using%20CMOS%20...

[haqreu]

AFAIK it was never built, only partially designed.