Slashdot Mirror
Home-Built Turing Machine
stronghawk writes "The creator of the Nickel-O-Matic is back at it and has now built a Turing Machine from a Parallax Propeller chip-based controller, motors, a dry-erase marker and a non-infinite supply of shiny 35mm leader film. From his FAQ: 'While thinking about Turing machines I found that no one had ever actually built one, at least not one that looked like Turing's original concept (if someone does know of one, please let me know). There have been a few other physical Turing machines like the Logo of Doom, but none were immediately recognizable as Turing machines. As I am always looking for a new challenge, I set out to build what you see here.'"
I admire people who build things like this, but at the same time I also wonder just why the heck they do it.
I guess that's the difference between people, I'd rather build something new than re-create something that's been done before. (Honestly not trying to sound like an ass, just find it interesting.)
maybe i'm missing something but i'm used to people talking about "turing machines" as a machine that is "turing-complete", not looking like a hypothetical turing machine he described in his paper. Is this aesthetics over the principle he meant it to be taken by? Cool hardhack though btw, love to have one of those on my coffee table.
WÌÌfÍ--ÍSÌÒÍ...Í...ÌHÌÍfÍÍÍ--ÍÍÍ
Hot Tub Turing Machine!
For social reasons I will refrain from mentioning this to my friends (which I have) later tonight. Baaaah, I want one! This is so pointless but nifty, my inner collector is crying out. Damn fiscal responsibilities in life tell me it's a waste of money, but oh, the geeky child inside cries out!
"Sorrow is better than laughter, for by sadness of face the heart is made glad." [Ecclesiastes 7:3]
No relays. How sad.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Purely technically, a Turing Machine that hasn't infinite tapes is simply a Finite State Machine. You cannot build a "real" Turing Machine. Doesn't make his creation less interesting though :-)
And you'd be wrong.... Computers are Finite State Machines with an insane number of states.
Couldn't that be said of any Turing machine? Whatever you build it out of is Turing-complete, I think.
RTFA. I know that's a sin, but seriously, do. You'll discover you are wrong.
The microcontroller loads the program as written in ascii on an SD card. It also can write the initial data onto the tape. After that, the computation is, indeed, performed by the "machine". Hence the optical reader for the characters on the tape.
A turing machine isn't just the head and the tape, its those things plus a state transition table. The microcontroller is doing the state transition table part.
Actually, if you'd bother reading the article, you'd find that the micro-controller is being used to do drive the electric motors, image process and maintain the turing machine's "state". that's it.
Sigs are for the weak.
Incorrect. The keyboard, mouse, and audio input insure it is indeed a Turing machine with infinite input.
- For the complete works of Shakespeare: cat
A Turing machine is supposed to represent what an infinitely patient mathematician with no insight can achieve when he has an infinite amount of paper and pencils. Obviously, the infinity here poses some problems, but you can build a finite Turing machine by finding a mathematician that has no insights,giving him tranquilizers to make him more patient, and locking him into your basement with some food and papers and pencils.
It looks like some berserk moderators got in here. Why all the troll mods?
The hardware is very elegant and well-done. The guy is a multi-talented geek of the highest order.
"Eve of Destruction", it's not just for old hippies anymore...
Wow...where can I buy a Turing-complete microcontroller?
Now, let's look at how this works. It reads a symbol from the tape using the camera. Then it checks its internal state, and sees what it should do with that symbol (should it change the symbol, change the state, and/or how should it move). Then it does that action and moves on to the next symbol as instructed by the last "rule". Considering that the only thing that the machine keeps track of from position to position is the state, it is indeed a Turing machine. The microprocessor's job (as he states) is to act as the read/write head for the machine. Turing never described HOW the head worked, just WHAT it did. And this head performs EXACTLY what Turing described. And that's why this is a Turing machine. If you wrote a program on your computer that did this, it too would be a Turing machine. The delineation is in how it handles and stores states, not the method in which it "processes" data... And Turing's original work described a Turing machine as using a person to perform the actions (but strictly following the ruleset). So I fail to see how this could possibly NOT be a Turing machine...
If a man isn't willing to take some risk for his opinions, either his opinions are no good or he's no good
The program would only ever be on the tape in the case of a Universal Turing Machine: http://en.wikipedia.org/wiki/Universal_Turing_machine...
If a man isn't willing to take some risk for his opinions, either his opinions are no good or he's no good
Ensure. Unless you mean those input devices actually insure your computer. Maybe that was part of the health care bill?
If you replace every instance of "Finite State Machine" with "Flying Spaghetti Monster", the post sounds more like a religious discussion.
I'm a good cook. I'm a fantastic eater. - Steven Brust
What I find tickling about this implementation is the clear evidence of an embedded FSM emulating the programmed TM.
The Flying Spaghetti Monster is embedded in the programmed Transcendental Meditation?
Proof of Intelligent Design!
Blasphemy is a human right. Blasphemophobia kills.
I believe the 1, 0 and blank are the characters of the TM's alphabet, not the states. The states are internal to the machine and there can be quite a lot of them depending on what the program is to accept the TM's language.
http://www.youtube.com/watch?v=cYw2ewoO6c4&feature=fvst
"The number you have dialed is imaginary. Please rotate your phone 90 degrees and try again."
Im impressed: For an infinite tape, the reels look very compact.
No, actually he was correct. Having an unlimited amount of input (over a finite alphabet) does not promote a finite state machine to being a (classical) Turing machine. If you want to have a real Turing machine, then you must have unlimited writable memory (as well as a few other things). Finite state machines handle unlimited input just fine. Actual desktop computers have "only" a finite (gigantic) number of possible states, assuming you don't let people swap in an unlimited number of new hard drives.
$META_SIG_JOKE