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Domain: abelard.org
Stories and comments across the archive that link to abelard.org.
Stories · 1
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A Model Railroad That Computes
tri44id writes "Several blogs have noted an Austrian team that has built a model train set that is a primitive computer. I have to point out, though, that it's actually only a Finite State Machine, like a pocket calculator, not a general-purpose device. Their plan for a general purpose layout is for an infinite-state machine, not a FSM+tape that Turing envisioned in his original paper. Turing took the concept a further step, by presenting a Universal Turing Machine that embodies a special set of states and transitions that allows its tape to be programmable to emulate any other TM. Do Slashdot readers know of any mechanical implementations of a truly Universal Turing Machine? (Danny Hillis' famous tinkertoy tic-tac-toe machine has neither infinite tape nor programmability, and is thus yet another FSM. It shouldn't be hard to elaborate the Austrian model train FSM to use a series of cars carrying movable magnets to represent Turing's tape cells writable with different symbols, and thus become a true TM or even UTM."