20 Questions - round 4

[axn]

Originally Posted by Zeta-Flux

I already guessed magnets, but I guess not... :-p

I'm guessing diodes.

[retina]

Maybe a NAND or inverter gate, or some other type of logic gate?

[lavalamp]

Originally Posted by retina

Maybe a NAND or inverter gate, or some other type of logic gate?

DING DING DING DING!

<?php
echo sha1(sha1(sha1("A NAND gate.")));	// 670d6661f375878426e6240f77d6fc1588d67d96
?>

[axn]

Hmmm... So the bit about "they're bloody everywhere" -- are you sure that modern electronics uses NAND, and not something like NOR?

[lavalamp]

I'm sure they're both regularly used, but as far as I am aware, NAND is the do-everything gate of choice. I realise that combinations of NOR gates can also be used to replicate all other gates, but as I say, NAND is the most popular I beileve.

Perhaps they are indeed, both bloody everywhere.

[Uncwilly]

A NAND gate is a logical item. While it can be constructed in a physical form as electronic, they have also been built in mechanical forms.

Originally Posted by http://www.nanomedicine.com/NMI/10.2.1.htm

In 1990, University of Minnesota engineers fabricated a complete family of micromechanical digital logic devices, including electrostatically-actuated linear-sliding ~30 micron mechanical logic elements confined to a one-dimensional track, forming NAND and NOR gates suitable for low-speed radiation-hard digital functions "in environments hostile to electronic devices."

Originally Posted by http://en.wikipedia.org/wiki/Logic_gate

Charles Sanders Peirce (1880) showed that NAND gates alone (or alternatively NOR gates alone) can be used to reproduce the functions of all the other logic gates, but his work on it was unpublished until 1935.

http://goldfish.ikaruga.co.uk/ornand.html an example manufactured of Lego's.

This video demonstrates that they can be constructed of Kinex http://www.youtube.com/watch?v=3vXlQZvS-nM

They can be electromagnetic as well.

I dispute (mildly) your answer that they are electronic.


BTW: maybe Retina should take the next round.

[lavalamp]

Originally Posted by Uncwilly

I dispute (mildly) your answer that they are electronic.

I strongly rebut your mild dispute.

Originally Posted by Uncwilly

The CM RCS has 1/200th the power of the SPS. And the CM RCS is used for less than 1/600th of the flight. It is not used to move it from the course, only to rotate the position.

Are you suggesting that mechanical or electromagnetic can operate at greater than 1/200 the frequency that NAND gates on VLSI circuits can, or that they are used for more than 1/600 the applications in the real world?

With your answer that the object was not capable of moving itself I ruled out all forms of space craft, because they must all be capable of moving themselves to some degree. At least, I am not aware of any that are not (other than dead satellites).

With my answer that the object was electronic, did you seriously rule out all logic gates because of a very few specialised purposes? All electronic devices could be replaced entirely with mechanical processes, it's just very impractical and difficult.

[retina]

NAND gates are certainly the most seen gates used in my experience. Also, there are more types of NAND gates available than there are AND, XOR, XNOR, OR or NOR gates (in discrete componentry anyway, FPGAs/CPLDs might be different).

Originally Posted by Uncwilly

BTW: maybe Retina should take the next round.

I don't mind trying to run one of these. But I screwed it up at the last question so I don't really deserve it. Unless lavalamp wants to take break then it is lavalamp that should start the next one. This current one was certainly very entertaining.

[lavalamp]

You specifically mentioned the exact answer, I'd consider that a win, go for it.

[Uncwilly]

Originally Posted by Uncwilly

I dispute (mildly) your answer that they are electronic.

Originally Posted by lavalamp

I strongly rebut your mild dispute.

If you meant "an electronic NAND gate" you should have put that as the input into the hash. :) But then, this is me ->

An item that is part of a computer (in the chips), isn't "connected" to it, it is it. I think some of the questions that lead up to that are the problem, directing thoughts.

With your answer that the object was not capable of moving itself I ruled out all forms of space craft, because they must all be capable of moving themselves to some degree. At least, I am not aware of any that are not (other than dead satellites).

The Ranger block II craft had a major sub-craft that was unable to move by itself. Solar sail craft can't move by themselves. Echo I could not move by itself. The Apollo sub-satellites could not move by themselves. From everything that I could find, Huygens could not move by itself.

[retina]

Originally Posted by lavalamp

You specifically mentioned the exact answer, I'd consider that a win, go for it.

Okay. Here 'tis.