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."

Comments

Just state machine?

[notany]

I haven't been fortunate enough to find a computer that was more powerful than a sufficiently large finite-state machine.

D'uh!

[Aardpig]

Do Slashdot readers know of any mechanical implementations of a truly Universal Turing Machine?

Of course not. A truly Universal Turing Machine needs an infinite amount of tape. Or RAM. Or HDD. Or Spaghetti. Or any other infinite amount of storage device. Hell, the submitter makes this clear in their spiel, just after they ask the vacuous question above. I guess they should read what they write a little closer; or stop prancing around like a tit, trying to sound profound and knowledgable.