Trinary Computers?

Is to possible to build a computer with more than the good ol' binary, on-off, 0-1 logic? The short answer is yes, though it may be uneconomical. The first (and only) modern trinary (or ternary) computer was Setun, built by the Soviet Union in 1958. 50 such computers were built for use at Moscow State University between 1958 and 1965. The programming language used on Setun was the Dialog System for Structured Programming (DSSP) which was a stacked-based programming language.

If you're wondering how ternary logic works, think of binary but add -1 to the list of value statements (-1, 0, and 1), though the Setun computer employed "balanced ternary" which only used the traditional 1 and 0 values. For an interesting biography on the creator of Setun, click here.