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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."
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?
The very first Lego device to be slashdotted
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
That's the newsworthy part. They created a mechanism that takes snide comments from the Internet, and converts them to mechanical storage!
You do not have a moral or legal right to do absolutely anything you want.
...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.
It's not... there's no infinite tape!
For a truly perverse experience it needs to be a Lego Turing machine to emulate an Apple ][ running LOGO to control the Lego Turing machine. I some how feel I have now stumbled upon some weird edge case of the halting problem related to my childhood and that I need to go dig out my computational theory book.
Time to offend someone
Wouldn't they have to be aleph-nullaires? I.e., the infinitesimal percent?
But, I wanted socialized health insurance!