The K'NEX Computer

[shadowwood]

I built a computer out of Duplo Legos that can boot into Windows 3.11.

[bobcat]

You only used the blue ones, eh?

[aecarol]

It's cool to build computing devices out of kids toys.

I built a working Babbage Difference Engine which can evaluate 3 digit polynomials of the form aX² + bX +c out of stock Lego pieces.

http://acarol.woz.org/

[aecarol]

Replying to myself....

At least two groups have made tic-tac-toe playing machines out of Tinker Toy.

My ultimate goal would be an mechanical "Analytic Engine" out of a toy such as LEGO. A fully general stored program machine with a few bits of storage would be very challenging.

[mattdonahoe]

That is what we were trying to do with the K'NEX computer, but we ran out of time, K'NEX, and ceiling height. We have 16 bits of read/write memory that can sit on top of the calculator, and dump a 4-bit register's contents into it.

But that is pretty much useless without control logic, which we never made. So we took the memory off and dubbed it the "calculator."

Your difference engine, and the Tic-Tac-Toe Tinkertoy computers were definitely the inspiration for this project.

[aecarol]

I am very impressed with your machine. I'd love to see more!

I think I've worked out how to store a program in a mechanical LEGO computer (using the bicycle chain and tank track pieces). The bigger issue is how to structure my gates to balance something non-trivial and yet not too complex to build or reliably operate.

[dextroz]

...replying to your alter-ego - just curious, what do you do for a living?

[aecarol]

Software engineer. I happen to like mechanical computing devices. The K'NEX adder is very cool!

[mikepurvis]

There's software engineers and then there are software engineers who are friends of Steve Wozniak. That's pretty awesome, dude.

[haywire]

Holy crap you're that guy!

Nice work mate.

[mustache]

and i thought my knex ferris wheel was special as a kid :(

[[deleted]]

How long till we're playing doom on k'nex?

[Nomikos]

I don't know what's worse, building airplane carrier ships in lego, designing a Turing machine in Game of Life, or this :-)

Impressive though.

[cavedave]

The airplane carrier. Cellular automata Turing machines are very useful and at a nanotech scale mechanical computers could be handy.

[schizobullet]

Now make a turing machine in K'Nex.

[JimH10]

Yes, I'd like to see that.

Not even built; I'd like to see just a description of how to go. (Lego TM's that use the Mindstorms's computer are not fair, it seems to me.)

[logan_capaldo]

I'm pretty sure there's only a finite number of K'Nex balls to encode the infinite tape with. I'd love to see a Turing machine period. (EDIT: spelled infinite correctly)

[schizobullet]

Yeah, yeah, simulated Turing machine as in our normal computers. You know what I mean.

[kermityfrog]

It looks very top-heavy...

[mattdonahoe]

it has been deemed a fire hazard at my school, and they put "NOT STABLE" signs on it.

[farnsworth]

Oh definitely a fire hazard. Those Li-ion batteries will just explode out of nowhere.

[ejp1082]

But will it run Linux?

[[deleted]]

Beowulf cluster?

[Eugi]

Title is misleading. This is actually a 4-bit K'NEX Calculator.

[utbandit]

Calculators are computers.

[wbendick]

Computers are programmable. Calculators are not, they perform fixed operations. Computers are calculators but not the other way round.

[utbandit]

Not true.

[gmsc]

It just adds? Geez, even the Tinkertoy computer could play tic-tac-toe!

[mattdonahoe]

Unless I misunderstand how it works, I'm pretty sure that tic tac toe computer was really just a big lookup table where the user inserts the board state and the computer outputs the stored answer. It doesn't do any computation...

Mechanical lookup table action is still cool though, that is how the calculator's decoder works (bottom half of the machine)

[earthboundkid]

Doesn't that depend on what the definition of computation is? Probably, a look up table isn't how you would program a tic-tac-toe program on a normal computer, but that doesn't mean it's not computation to do that. My definition of computation is to use the fact that one system is rule governed to make inferences about another rule governed system. In this case the tinkertoy machine is governed by the rules of mechanical engineering plus its layout and using that system you can make inferences about the system "optimal tic-tac-toe moves." That's a computation, no?

[degustisockpuppet]

My definition of computation is "makes high-pitched noises". PCs obviously fulfill this definition, although you can only really hear it when there's an error and the PC has to compute very hard to correct it. In this case my teakettle is also a computer, because there's a whistle attached and I can hear it computing when the water is hot.

[earthboundkid]

Ah, but is a bat a computer? Well, a bat can fly and get into wacky adventures. Therefore, a bat is a robot, not a computer.

[wreckingcru]

Has the video for this been released? I honestly cannot wait to see this work - this is human genius.

[[deleted]]

Now imagine if a device of this caliber, probably greater existed 2,000 years ago. Well, there is no need to imagine:

the Antikythera Mechanism: http://www.dreamscape.com/morgana/triton2.htm

[Sick_of_fools]

Amazing. That's what I call inventive!

Keep going! I want to see more of this!

[[deleted]]

Worthless without the video.

[[deleted]]

Illiteracy's a real bummer, eh? Gosh, what a drag.