A ternary computer, also called a trinary computer, is one that uses ternary logic in its calculations. Most computers use binary logic (base 2 logic) where each fundamental piece of information can be represented as one of two values: say, "0" or "1"; each of these fundamental units is called a "bit". With ternary logic (base 3 logic) each fundamental piece of information can be represented as one of three values: say, “-1”, "0" or "1"; by extension of the language each of these fundamental three-value units is called a "trit".

So a ternary computer, unlike most computers, uses trits rather than bits in its processes. An advantage of a trit-based system is that advances in ternary computer architecture create the possibility of making some arithmetic computations more efficient in than in comparable binary systems.

The ternary system is not just a theoretical abstraction. The world's first ternary semiconductor design on a large wafer was implemented by the research team at Ulsan National Institute of Science and Technology in South Korea, which will help development of low power and high computing microchips. This research theme was selected as one of the future projects funded by Samsung in 2017.

With the coming of relatively inexpensive mass-produced components for binary computers, ternary computers have diminished in significance. However, some argue that they will be brought back into development to take advantage of ternary logic's elegance and efficiency.

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