There are 10 Kinds of Computers in the World

There’s an old joke that there are 10 kinds of people in the world. Those who know binary, those who don’t, and those who didn’t see a base three joke coming. Perhaps [Dmitry Sokolov] heard that joke because he’s built a ternary (base 3) computer. He claims it is the first one to be built in the last 50 years. You can see a video about the device below. There’s also a video of the device with a nixie tube output.

You may not think of it often, but bit is a contraction of binary digit, so a ternary computer doesn’t have those. It has trits. The CPU operates on 3 trit words and uses nothing but multiplexers as building blocks. Instructions use 5 trits, some of which are a two-trit opcode and a 3 trit address of one of the 13 registers. The allure of using ternary, by the way, is that you can represent more numbers in fewer bits — um, trits, rather.

That might seem like an odd number of registers, but using balanced ternary, a 3 trit word can represent numbers from -13 to 13, so it makes sense. Instead of a bit’s 1 and 0 state, a balanced trit has -1, 0, and 1 states. To prevent confusion, [Dmitry] uses the notation N,0, and P when talking about a ternary word. For example, 101 is 10 decimal or P0P in his notation. To represent -10, you simply use NoN, instead.

The multiplexers use an analog switch, the DG403. We’ve talked before about making logic gates out of muxes, but — of course — those were the binary kind. However, we aren’t too sure this is really the first of its kind in 50 years since we remember a Hackaday Prize entry that was similar. In fact, the designer gave a talk about her CPU at last year’s Hackaday Superconference. Still, this is an impressive piece of work.

The Russians did a lot of work in this area back in the 1950s. If you can read a little Russian, you can always go try their emulator online.