A Turing Machine Built With Lego, And a Place To Put It
New submitter Otis_INF writes "To honor Alan Turing, two researchers at the CWI built a simple LEGO Turing Machine, to show everyone how simple a computer actually is. Primary goals were to make every operation as visible as possible and to make it using just a single LEGO MINDSTORMS NXT set."
And if a simple Turing machine gets old, Reader miller60 adds a link to this Lego data center "that recreates all the major features of an IT facility, assembled from 5,772 pieces, 28 figures, and 1 meter of fiber optic cable. The builder, Tanaka, has uploaded details to the Lego Digital Designer Gallery so others can build and adapt their own."
It's a Turing machine dammit, not a web server!
Set your phasers on "funky"!
My personal opinion: I don't like their implementation.
I would prefer to see a version which uses a long "tape" which is covered in a thin film and the data recorded using different coloured dots from whiteboard markers.
Just my 2.
No sig. Move along - nothing to see here.
At Turing machine has infinite tape (memory). You cannot build one in the real world**. This is a deterministic LBA (linearly bounded automaton). **for two reasons preventing infinite storage: 1. a real world automaton is limited in extent by its light cone, and you cannot rely on this growing forever since accelerating expansion of the universe eventually will prevent outer parts of the device from communicating back with lightspeed signals 2. the Bekenstein bound limits information density: you can only store a finite information in a finite space--so no arbitrary precision real numbers
"Politicians and diapers must be changed often, and for the same reason."
Modular design is certainly the way most new data centers are going!! And who is more modular than Lego????????
As has been (kinda harshly) hashed out on hackernews, this is really a turing machine emulated on a NXT using lego as a physical memory display. This is still cool, but its not "turing machine built out of lego" except by the extreme interpretation that a NXT computer is sold by the lego corporation.
There have been some genuine mechanical turing machines built with varying level of success.
Its pretty easy to make an electromechanical relay based turing machine if for no reason other than price (well, price compared to when I was a kid, its still gonna be a chunk of change)
When I was a teenage kid a simple DPDT 12 volt relay at radio shack cost me something like two HOURS of labor income, and now as a "highly" paid jack(-ass) of all computational trades I can buy a simple DPDT from Mouser for something like two MINUTES of labor income. I've got a bitslice ALU design (admittedly not a turing machine) down to about 22 relays per bit. Latching relays are about 50% more money than non-latching. Also QPDT relays are "cheap" and commercially available.
large PCBs are expensive. Yet sockets and hand wiring is not cheap either (although it looks cool)
I'm stuck on (electro-)mechanical memory storage devices. There was a single bit core memory design from a 1970s electronics magazine that used simple steel washers as cores, terrible magnetic properties but cheaply and widely available. However I don't want an electronic design. Latching relays are cheap enough for registers and ... surprisingly enough ... latches ... but they're a bit expensive for main memory. For example an Altair size of memory made of latching relays would cost me about 256 bytes * 8 bits * 3 bucks per latching relay equals $6.1K just for storage not to mention decode logic. Until I can figure out a way to get below $1/bit purely electromechanically I think I'm stuck.
The history of computation, since the 1940s (before even my time) has always been "computation is cheap, memory is expensive"
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
http://www.youtube.com/watch?v=cYw2ewoO6c4
Do you care about the security of your wireless mouse?
I am not quite sure, but I think that they built a Turing machine, while I think these people [1] built a universal Turing machine.
[1] http://graal.ens-lyon.fr/rubens/
The very first Lego device to be slashdotted
Table-ized A.I.
In theory it actually can run Linux (if you are really really patient)
Table-ized A.I.
Otherwise, how the heck did they come up with an infinitely long tape?
I am officially gone from
If Professor Turing patented a TM these days, he could sue for royalties on every computer, big and small. I almost wish he had as revenge for the crappy way the British gov't treated him.
Table-ized A.I.
Lego is a corporation.
In America, that makes him a REAL boy!
Careful, that's totally different than a Real Doll.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
...but I'd like to see how they'd implement the lambda calculus in Lego.
Maybe this is how one finally proves, after decades of bickering and argument, which model of computation is better- by seeing which one looks prettier when you make a visualiser for it out of brightly coloured snappable bricks.
http://videotheque.cnrs.fr/video.php?urlaction=visualisation&method=QT&action=visu&id=3001&type=grandPublic
Unfortunately, the video is in french. The machine works with Lego pneumatic cylinders so it's entirely mechanical.
A Turing machine is defined by a tape and a manipulator, and a state machine defining how those tape symbols are manipulated. The former is visible in the video. The latter is not. It appears they're using a mindstorm (itself a microcomputer) to perform the function of the state machine. I think this is cheating.
In fact, the whole state machine part of the Turing machine has always been rather nebulous to me. Yes, I understand the state transitions, but no physical mechanism is described (in CS theory texts) to implement it. The only physical parts of the TM are the tape and manipulator, while the state machine is left as an exercise for the imagination of the reader. In a way, I think that's cheating too.
The only reason it's "simple" is that one of its parts is a full computing device.
I'd have preferred a "hardware" implementation...
Born June 23, 1912
Mindstorms has a computer in it. That's cheating.
It's not very impressive to build the simplest possible computer out of... a vastly more powerful computer!
Just what is _that_ supposed to demonstrate?
I do love legos though..