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A DIY Turing Machine

Illustration for article titled A DIY Turing Machine

Mike Davey wanted to build a real Turing machine, but unfortunately he could not find the infinitely long tape required for the project. His solution? Using 1000 feet of white 35mm film leader and a dry erase marker. Result? Brilliance.


Davey's description of the machine almost makes your head spin a tiny bit, but after watching the video above, it'll make far more sense:

Although this Turing machine is controlled by a Parallax Propeller microcontroller, its operation while running is based only on a set of state transformations loaded from an SD card and what is written to and read from the tape. While it may seem as if the tape is merely the input and output of the machine, it is not! Nor is the tape just the memory of the machine. In a way the tape is the computer. As the symbols on the tape are manipulated by simple rules, the computing happens. The output is really more of an artifact of the machine using the tape as the computer.


I think Alan Turing would be proud. [Touring Machine via Make]

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Alan Turing, OBE, FRS (1912-1954) was British mathematician best known for his code-breaking work in WWII. In 1936 he wrote a seminal paper titled "On Computable Numbers" in which he described a hypothetical computing engine that later came to be called a "Turing Machine". It consisted in an infinitely long tape, a transport mechanism, and a head that could read, erase and write symbols on the tape. Turing showed that the tape mechanism, along with a set of transition rules for changing symbols, was capable of performing any conceivable computation. He never intended such a machine to actually be built; it was a thought experiment intended to illustrate the limits of computability. His work led directly to the development of modern computers during and just after the war.

A few people have built working models, although they are not true Turning Machines as they have finite tapes. The one shown here is the nicest one I've seen. Well done.