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Propeller driven Turing machine — Parallax Forums

Propeller driven Turing machine

macrobeakmacrobeak Posts: 354
edited 2014-12-15 10:40 in Propeller 1
I don't know if anyone else has noted this.
Interesting, a very modern kind of computer to demonstrate the first kind of computer.
http://spectrum.ieee.org/automaton/robotics/artificial-intelligence/032610-diy-turing-machine

Comments

  • PublisonPublison Posts: 12,366
    edited 2014-12-15 03:04
    Martin_H found that machine four years ago, and the builder, (Mike), responded with a post.

    http://forums.parallax.com/showthread.php/120975-Mike-Davey-s-Turing-machine

    I'ts been a while since I viewed the video. Thanks for bringing it up!
  • TorTor Posts: 2,010
    edited 2014-12-15 05:40
    Thanks from me as well, I hadn't seen it before. But I wonder: Shouldn't the program itself also be executed from the/a tape? I seem to remember that as an essential part of the Turing tape machine.
  • Heater.Heater. Posts: 21,230
    edited 2014-12-15 07:53
    Tor,
    Shouldn't the program itself also be executed from the tape?
    Yes. Actually it's still not clear to me what is going on here.

    At the lowest level the machine needs to be able to write symbols to the tape, read symbols from the tape and wind the tape up and down. It has to be able to make decisions about what to write and how far to wind the tape dependent on what it has read from the tape.

    That could all be done with logic gates but, hey, why not do it with a program in a Propeller?

    At the higher level there is a program on the tape itself. Which gets executed by the mechanisms mentioned above.

    Somewhat like having a Spin bye code interpreter, a program in it's own right, executing a Spin program by interpreting the Spin byte codes. In that case the HUB RAM is analogous to the tape, it's just bunch of symbols laid out linearly right, and the COG running the interpreter analogous to the Turing machine mechanism.

    Or think of Conway's Game of Life. A computer runs a program that creates and erases "cells" on a grid according to some simple rules. Those cells and rules together are sufficient to describe a computer in themselves and run programs at a higher level. Conways Game of Life is Turing complete.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2014-12-15 09:21
    Tor wrote:
    Shouldn't the program itself also be executed from the/a tape? I seem to remember that as an essential part of the Turing tape machine.
    The only requirement is that the machine logic be a finite-state automaton. It doesn't have to execute code from the tape to qualify as a Turing machine.

    -Phil
  • StefanL38StefanL38 Posts: 2,292
    edited 2014-12-15 10:40
    posing questions and ideas is far easier than do realise or to solve it

    anyway: Is this a wrong-category idea or does this make sense: How about a hardware demonstration of Brainf***?

    or as my ideas began to spill out: how about a turing-machine-variant with writing the numbers into sand moving up and down the beach?

    This remembers me of Bruce Shapiro who does some great Art with electronics
    what I like most is this one: http://www.taomc.com/art/permanent_installations/pipedream_series/pipedream_iii.html

    best regards

    Stefan
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