what is computer

what is a computer?

The first sentence should be something like: "A computer is an information processing machine which is capable of simulating any other information processing machine that can fit into its memory." There are three salient parts to the definition:

 -information processing machine
-capable of simulating any other ( like a Universal Turing Machine )
-can be built in real life, so can't have infinite memory ( unlike a Universal Turing Machine )

Currently the first sentence of the article says "A computer is a machine that manipulates data according to a list of instructions", which is only one particular (but dominant) category of computer architecture -- Instruction Set Architecture. Other real life categories which are actually sold are:

 parallel/multi-core -- one computer processes many lists of instructions in parallel
reconfigurable/FPGA -- the computer is specialized for simulating any logic network

And some other classes which have only had prototypes:

 stream processors
cellular automata simulators (probably only one of these was ever made (Margolis))
dna computer  —Preceding unsigned comment added by 70.20.219.7 (talk) 03:31, 25 January 2008 (UTC)

While your opening would probably stand up better as a formal definition, I'm not sure that's the best route to follow for an article which is intended to be an accessible introduction to computers. Remember, this article isn't about theories of computation or computability, but about "computers". The term "computer" has a vernacular meaning to society which is every bit as significant as the formal basis. The writing of the article tries to balance these two worlds by introducing computers in fairly familiar terms and then branching out slightly into instruction set (or Von Neumann) architecture. I believe this is a good approach because, as you state, this is the dominant realization of computers and will cover most anything that a typical person will think of as a computer (thread-level parallelism really doesn't break significantly from the "list of instructions" concept, either). With some of your examples (stream processors, special-purpose logic and DSP, DNA computing, etc), there's probably a good bit that can be said about whether these even are computers (the classical "where is the line between a computer and a calculator" question). We run into the issue of a heavily overloaded term in "computer", so we took the tact of making an article as accessible yet informative as possible to a general reader. I really think it would only complicate matters to try to introduce much computing theory in this article, especially since there are a lot of other articles dedicated to the theoretical aspects of computers. -- 74.160.99.252 (talk) 19:07, 11 February 2008 (UTC)

A computer can't be a machine, because the Wikipedia entry for machine excludes computers.Heikediguoren (talk) 21:14, 10 July 2008 (UTC)

The Wiki article for machine is in grave error and should be corrected; analog and digital computers both fall under the broader category of "machines". See Association for Computing Machinery, "the world's first scientific and educational computing society" (and still going strong).

The 3rd edition of the Concise Encyclopedia of Science and Technology (Sybil P. Parker ed., 1994, McGraw-Hill) defines "computer" as "A device that receives, processes and presents information. The two basic types of computers are analog and digital." (Note: A computer doesn't require "a list of instructions".) A broad definition indeed, but the introductory paragraph can quickly set aside the analog variety, which are still in heavy use, although we don't commonly think of them as "computers". Any analog meter, gage, motor driven clock, speedometer, odometer, etc. qualifies as a computer.

I'm not sure "Modern computers are based on tiny integrated circuits…" is the proper phrasing. How about, "Modern electronic computers rely on integrated circuits…" The CPUs in PCs and Macs aren't so "tiny" – it's a relative term anyway.

Btw, the caption that reads, "Microprocessors are miniaturized devices that often implement stored program CPUs" is all wrong; it doesn't even make sense. Microprocessors are literally integrated circuit (as opposed to discrete circuit) electronic computers – computers on a chip. And "central processing unit" should appear earlier in the text. As is, we see "CPU" before we're told what the letters stand for.