What if our computers hadn't been binary? We take bits, zeros, and ones for granted, as if binary computing were the only possible way to build a computer. But in 1958, Soviet researchers at Moscow State University built Setun, a real computer based on balanced ternary: −1, 0, and +1. It wasn't an experiment on paper: Setun was produced, programmed, and used for years.

In this talk, Horacio will explore what happens when a bit becomes a trit. How do you represent positive and negative numbers? How does arithmetic work? What do memory, instructions, registers, and conditional branches look like? He will dissect Setun's surprisingly elegant architecture and go all the way to building an emulator capable of running its instructions. Along the way, he will explore why base 3 has some fascinating mathematical properties, including the radix economy argument, and why, despite them, binary ultimately became dominant.

But ternary computing never completely disappeared. Three-state logic lives on in TCAMs used in networking, ternary weight quantization is behind current research into 1.58-bit large language models (LLMs), and quantum computing is exploring qutrits alongside qubits. Setun may be a computer from 1958, but the ideas behind it are surprisingly alive today. Maybe binary wasn't the only possible future after all.