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Comment by pavlov | Hacker News Reader

My favorite "lost" type of computer is the balanced ternary machines. These were actually built in the Soviet Union in the 1960s:

https://dev.to/buntine/the-balanced-ternary-machines-of-sovi...

Programming with trits and trytes!

Unfortunately, domestic Soviet computers were effectively killed by a 1970 decision to base all future efforts on a "Unified System" which was really a clone of IBM System/360: https://en.wikipedia.org/wiki/ES_EVM

Playing it safe by shooting yourself in the head...

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"But I do believe that much wisdom can be sought by looking into the past"

exactly why I'm learning AWK via the gray book

Can always look ahead to programming with entangled qubit-qutrits :-)

https://phys.org/news/2008-02-physicists-qubit-qutrit-entang...

I had always wondered if someone had ever built a ternary computer. Would it even be practical to build one today? Given that binary computers rule the computing world these days, I'm not sure there would really be much use for it.

I've previously heard of ternary computers as a concept, but I don't think I'd heard of any actual implementations until now. Thanks for the link.

Are there major benefits to ternary computation?

I pulled out my copy of Knuth vol 2 to answer this (pages 190-193):

* You can negate a number by interchanging 1 and ̅1.

* The sign of a number is given by its most significant non-zero trit.

* Rounding to nearest integer is the same as truncation.

By the way if we had balanced ternary computers today, then you wouldn't have programming languages with signed and unsigned integers. They'd be the same thing.

Of course the above might be academic if it's more difficult to implement in CMOS ...

Edit: Also you can argue that the most economical radix is e, and 3 is closest to this ideal. See: https://web.williams.edu/Mathematics/sjmiller/public_html/10...

Edit #2: Removed the claim that addition is easier than binary. I misread what Knuth was trying to say.

Representing binaries numbers with explicit sign bit and the rest unsigned gets you an even better version of that; this is how floating point handle the sign.

I'm skeptical of value of ternary. The key behind the success of binary computers is that binary has great noise immunity; having a _single_ threshold is way simpler to get working than two or more. (Yet we do go there for NAND Flash, but note how speed and endurance worsen dramatically as thresholds are added).

The "most economical radix" is often cited but it's a red herring - it ignores practical concern of greater importance.

suppose that we got robust practical 3 level logic elements, then potentially we'd need less of them for the same bit-width of computation thus less energy consumption, and the multiply&divide can probably be done in lesser number of cycles.

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