A LEGO Turing Machine For [Alan]’s Centennial

2012 is the 100-year anniversary of [Alan Turing]’s birth, and to celebrate the centennial, [Jeroen] and [Davy] over at Centrum Wiskunde & Informatica in The Netherlands built a Turing machine out of LEGO.

A Turing machine is an extremely simple device, but is still able to compute everything your desktop can. The machine is generally described as an infinite paper tape with a read/write head. On this paper tape, the numbers ‘1’ and ‘0’ are written. By precisely defining what the Turing machine should do when it comes across a ‘1’ or ‘0’, its able to do the same calculations as a laptop, albeit at a much slower rate.

The LEGO Turing machine has a series of pins signifying each bit. These pins are moved underneath a read/write head containing a light sensor and robotic arm. When a pin is down, the camera sees a dark spot signifying one state. When the pin is up, light reflects off a white LEGO piece signifying another state.

[Jeroen] and [Davy] built an IDE for their Turing machine, so if you’ve got a few LEGO NTX bricks lying around you can grab the Git and build your own. Check out the mini documentary after the break.

12 thoughts on “A LEGO Turing Machine For [Alan]’s Centennial

  1. technically speaking a Turing machine can write any symbol in its alphabet, it is not limited to 2 symbols. In addition to its alphabet a TM can also read a special ‘blank’ symbol; the infinite tape is initialized with the program input and this ‘blank’ symbol everywhere else.

    since the lego TM seems to only have two possible states, one needs to be the blank, leaving only one symbol for the TM to use.

  2. it is also clear from the video that the LTM is running a classic adder TM, the adder only has one symbol defined (canonically ‘A’), and a ‘blank’ symbol. notice in the video that the numbers shown are in a unary (counting) number system. the result 4 is 1111 (AAAA) not 0b100!

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