The Soviet Union Built Computers That Processed Math in Threes, Not Twos
In 1958, computer scientists at Moscow State University built Setun, a mainframe computer that operated on ternary logic instead of binary logic. Using values of -1, 0, and 1, Setun processed numbers using 'trits' rather than bits. The three-state logic required fewer electrical components and calculated arithmetic faster and more naturally than binary hardware of the era.
The Logic Beyond Two States
Modern digital computing is almost universally built on binary logic. In standard binary systems, information is broken down into bits, each taking one of two states: zero or one, off or on. While binary has become the default due to the simplicity of physical switches, mathematical theory does not mandate base two. Information theory suggests that the most efficient integer base for representing numbers—a measure known as radix economy—is base three, closely approximating the mathematical constant e (roughly 2.718).
In the 1950s, early computer designers were not yet locked into the standard architectures used today. Hardware components like vacuum tubes and early semiconductors were expensive, bulky, and prone to failure. Minimizing the total number of components required to perform calculations was a major engineering priority. This mathematical and physical reality led a team of Soviet researchers to question whether base two was truly the best foundation for a digital machine.
The Creation of Setun
In 1958, a team at Moscow State University led by engineer Nikolai Brusentsov, with support from mathematician Sergei Sobolev, designed and constructed a working ternary mainframe computer. They named the machine Setun, after the Setun River that flows near the university campus.
Rather than using traditional binary bits, Setun operated on ternary digits, known as trits. Each trit could hold one of three distinct values. To store and manipulate these values, the team utilized miniature ferrite cores combined with semiconductor diodes. By exploiting the magnetic properties and hysteresis loops of these core-diode elements, the hardware could reliably represent three stable magnetic states, creating a functional three-valued logic gate with fewer physical elements than an equivalent binary system.