What is a Computer?
General:
A computer is a device capable of performing computations and making logical decisions at speeds millions, even billions, of time faster than human beings can. For example, many of today's personal computers can perform hundreds of millions, even billions, of additions per second. A person operating a desk calculator might require decades to complete the same number of calculations a powerful personal computer can perform in one second. Today's fastest supercomputers can perform hundreds of billions of additions per second about as many calculations as hundreds of billions of thousands of people could perform in one year! And trillion-instruction-per-second computers are alreadyfunctioning in research laboratories!
Computers process data under the control of sets of instructions called computer computer programs. These programs guide the computer though orderly sets of action specified by people called computer programers.
The varios devices that comprise a computer system (such as the keybord, scren disks, memory and processing units) arereferred to as hardware. The computer programs that run on a computer are refferred to as software. Hardware costs have been declining dramatically in recent years, to the point that personal computers have become a commodity.
Unfortunately, software-development costs have been rising steadily, as programmers develop ever more powerful and complex applications withoutbeing able to improve significantly the technology of software development.
Details:
A computer is a device that accepts information (in the form of digital data) and manipulates it for some result based on a program or sequence of instructions on how data is to be processed. Complex computers also include the means for storing data (including the program, which is also a form of data) for some necessary duration. A program may be invariable and built into the computer (and called logic circuitry as it is on microprocessord) or different programs may be provide to the computer (loaded into its strage and then started by ab administrator or user). Today's computers have both kinds of programming.
Most histories of the modern computer begin with the Analytical Engine envisioned by Charles Babbage following the mathmatical ideas of George Boole, the mathematician who first started the principles of logic inherent in today's digital computer. Babbage's assistant and collaborator, Ada Lovelace,is said to have introduces the ideas of program loops and subroutines and is sometimes cosidered the first programmer. Apart from mechanical calculators, the invention of the transistor, which then became embedded in large numbers in integrated circuits, ultimately making possible the relatively low-cost personal computer.
Modern computers inherently follow the ideas of the stored program laid out by John von Neumann in 1945. Essentially, the program is read by the computer ne instruction at a time, an operation is performed, and the computer then reads in the next instruction, and so on. Recently, computers and programs have been decised that allow multiple programs (and computers) to work on the same problem at the same time in parallel. With the advent of the Internet and highterbandwith data transmission, programs and data that are part of the same overall project can be distributed over a network and embody the Sun Microsystems slogan: gThe network is the computer.h