One of the problems with a classic Turing machine is the tape must be infinitely long. [Mark’s] Turing Ring still doesn’t have an infinite tape, but it does make it circular to save space. That along with a very clever and capable UI makes this one of the most usable Turing machines we’ve seen. You can see a demo in the video below.
The device uses an Arduino Nano, a Neopixel ring, an encoder, and a laser-cut enclosure that looks great. The minimal UI has several modes and the video below takes you through all of them.
You can even store tapes to EEPROM or the serial port, so that’s even more practical. Of course, you might wonder what practicality is a Turing machine? The honest answer is not much, but on the bright side, this one also has a clock mode so even when you aren’t explaining how a Turing machine works, it will make a good conversation piece.
We were impressed with the lettering on the case in addition to the simplicity of the user interface. [Mark] had won the LED ring in a competition so the total cost of this — to him — was low, but it wouldn’t be too much even if you bought all the pieces.