How To Build Your Own LEGO Turing Machine
Turing would have turned 100 on Saturday. He was 24 when he described his Turing machine — originally known as the “a(utomatic)-machine” — a device that reads and writes symbols on a strip of tape according to a particular set of rules. In short, it’s a computer. The same basic concepts underpin every computer we use today.
To build one, you need a tape, something to move it backwards and forward, and a head that reads and writes the symbols. Landman, van den Bos, and Klint built theirs using a single box of LEGO Mindstorms NXT, a set of LEGOs that includes various motorized parts and a mini-computer. In this case, the tape isn’t really a tape. It’s a set of LEGO “angle connectors” that act as switches.
Each connector can move back and forth between two positions, and these positions represent 1s and 0s. A rotating LEGO beam can move the connectors from position to position, and a light sensor reads the positions. Turing described a machine with an infinite tape, but the Dutch team didn’t have infinite LEGOS. They settled on a tape with 32 positions.
A Turing Machine made from LEGO just might be better than a LEGO Difference Engine…