This is an example of a mechanical computer. There are other popular computer implementations in Dwarf Fortress, including fluidic (pumping water around) and biological (enclosing creatures in specially-designed mazes).

Once the basic logic gates are designed, it's easy (though tedious and time-consuming) to build arbitrarily large computing devices. One famous example is a multifunction calculator, documented at < http://df.magmawiki.com/index.php/User:BaronW >.

Building amazingly complex (if tedious and time-consuming) objects in Dwarf Fortress is pretty much what the game is about after you manage to get past the early learning stages.

This is the kind of game I would recommend to hackers - it definitely supports the mind set of figuring out the rules in a system, then exploiting them to build something incredible.

For example, I remember discovering that if you build your dwarf fortress in certain freezing climates, it was possible to take water from a flowing source underground, then release it aboveground, whereupon it would flash-freeze into solid walls that dwarves could stand on, tunnel through, or build on top of. That immediately led to Operation: Build An Enormous Ice Palace, a plan to create an aboveground megaplex by making dwarves haul unfrozen water bucket by bucket and pour it, like concrete, into a planned mold. (I was exploiting the loophole that water carried in a bucket does not freeze until dropped from the bucket.)

It was ridiculous, arbitrary, and destructive of my free time - but most games are anyway... so why not take a game that also challenges your hacking mindset?

I have long assumed that it will eventually be a moral quandary as to whether or not it will be ethical to turn off dwarf fortress.

I think the question will be whether it's ethical to start a game that commonly ends in mass starvation, riots inspired by the rotting corpses of one's closest friends, and sometimes even running out of booze.

Some believe that God has already created just such a game.

Some years ago someone figured out how to build logic gates in Quake 3 maps out of doors and shooters (entities that shoot a projectile when triggered). This was actually used in some single player maps and to create special game modes that aren't present in vanilla Q3.

I guess this could, in theory, be used to create a Turing Complete computer. It might hit the entity limit of Quake 3 though.

PDF: http://www.skore.de/images/stories/Q3A/Q3A_Electronics.pdf

Presumably the next step is to write Dwarf Fortress for this.

My first CS course in college was Structure and Interpretation of Computer Programs. It was quite a thrill when we finally got our hand-written Scheme interpreter to run itself and give us a REPL prompt. Turtles all the way down.

Imagine a Beowulf cluster of these (I know, there were no dwarves in Beowulf, but it's still mythical).

I think the question we are all wondering is whether or not the computational engine here can be used to aid the dwarf decision making and increase automation and profit margins?

It's interesting that from a design complexity standpoint, what he did was way more difficult than say building Craigslist.

Perhaps that leads to his next challenge: upgrade the computing power of his DF contraption enough that he can reimplement Craigslist on top it!

I particularly liked kitten logic:

http://df.magmawiki.com/index.php/User:Bidok#Animal_Logic

Semi-related: LittleBigPlanet 8-bit calculator: http://www.youtube.com/watch?v=ZiRgYBHoAoU

...and begins to learn at a geometric rate.

I suppose it would be vaguely on-topic to mention the WireWorld computer, a particularly pretty MOV-machine implemented in the WireWorld cellular automaton:

http://www.quinapalus.com/wi-index.html

This is right up there with the Universal Turing Machine implemented in Conway's GoL (http://rendell-attic.org/gol/utm/index.htm).

Dude, I totally implemented Reddit in a weekend in Dwarf Fortress...

Now he should port his DF-based computer to run on the iPhone, that way he could use it as a sort of "intermediate layer" with .... looks at 3.3.1 ... oh, nevermind.