A Turing Machine

20th Century British mathematician Alan Turning is popularly known for helping to break Nazi Germany’s Enigma code and devising the Turing Test, which is an assessment of artificial intelligence. But he also made major, direct contributions to early computer science. Among them was a 1936 proposal for a computer, which Mike Davey recently built:

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.

The heart of the turing machine is the read-write head. The read-write head transports the tape and positions cells of the tape appropriately. It can read a cell determining what, if any, symbol is written there. The machine works on, and knows about, only one cell at a time. The tape in my machine is a 1000’ roll of white 35mm film leader. The characters, ones and zeros, are written by the machine with a black dry erase marker.

Link via CrunchGear | Previously on Neatorama: Math Explains How the Leopard Got Its Spots