NXT Turing Machine


This interesting use of Lego popped up on the mailing list of the University of Bergen. Build by a group of Norwegian Danish students, it’s a simple computer that implements Alan Turing’s design from 1937. Having both read and write functions, it implements its own (somewhat inefficient) medium of non-volatile memory. What we find interesting is that rather than move the ‘tape’ through the machine, the machine rolls over the tape. Thanks to [Thorsten] for the tip.

20 thoughts on “NXT Turing Machine

  1. Damn… Since i’m a child, i ask my parents to make them buying me some Mindstorm…. But i’ts still too expensive !

    Now that i’m a big and strong young men hwo lives alone in a little appartment, it still to expensive.

    This is my punishement for usign Real mode programming, ASM, and Pics… u___u

    So this is a really awesome build! “This is the power between our hands, a powerful computer built from Legos”


  2. Ever since the first generation Lego Mindstorms kit came out, I’ve craved to own one. I’ve played with several of the kits, and only touched the tip of the iceburg on what they were capable of doing, and what could be built with them.

    Then lego introduced the NXT mindstorm. I’ve never laid hands on one, but from what I’ve seen online, they have an incredible amount of uses like demonstrated here.

    My question is however, does anyone actually know what use this is as a calculator/volatile memory device?

  3. (Given Infinite Tape) There is nothing your PC can do that a Turing complete machine cannot do. The difference is in speed, but not capability.
    And as sol and the makers pointed out having a machine that can physically complete the operations of DFAs and NFAs would greatly help in working out how it all works.

  4. @sol

    I agree, it is pretty amazing to see something like a computer constructed out of a computer, but what can it do, can it be hooked to a computer to do useful operations?


    “(Given Infinite Tape) There is nothing your PC can do that a Turing complete machine cannot do. The difference is in speed, but not capability.”

    Will it play doom?

  5. Awesome! I’ve always wanted to do a physical TM, but lacked the time, motivation, and all that stuff… It’s wonderful to see someone actually go do it. And the video on top… genius!

  6. I must say, that is quite cool! Useful? Practical? Absolutely not! A good learning experience? For sure!

    Not having read any of the details quite yet, I assume they implemented the “virtual cpu” on the NXT, so that the Turing machine can be programmed with flipping glorious Lego bits.

    And yes, a Turing machine can –by definition– do any operation that any other computer can. I don’t know how many miles of Lego bits they’d need to program it to do something like multiplication but “given infinite tape” (as was stated above) and near-infinite time this thing could multiplicate, divide or even run linux.

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