Thursday, November 18, 2010

What Is Computer?

A computer is a programmable machine that receives input, stores and manipulates data, and provides output in a useful format.
While a computer can, in theory, be made out of almost anythingWe are all familiar with what a computer is in a specific, contemporary sense. Personal computers are found in most aspects of daily life, and for some it is hard to even imagine a world without them. But the term computer meaComputers range from the very small to the very large. Some are capable of doing millions of calculations in a single second, while others may take long periods of time to do even the most simple calculations. But theoretically, anything one computer is capable of doing, another computer will also be able to do. Given the right instructions, and sufficient memory, a computer found in a wristwatch should be able to accomplish anything a supercomputer can — although it might take thousands of years for the wristwatch to complete the operation.
At one time, computers were extremely large, and required enormous amounts of power. This made them useful only for a small amount of tasks — computing trajectories for astronomical or military applications, for example, or code breaking. Over time, with technological advances, the computer was scaled down and its energy requirements lowered immensely. This allowed the power of the computer to be harnessed for a staggering array of uses.
As prevalent as personal computers are, they do not nearly begin to scratch the surface of computer use in our world. Interactive devices of all sorts contain their own computers. Cellular telephones, GPS units, portable organizers, ATM machines, gas pumps, and millions of other devices all make use of computers to streamline their operations, and to offer features which would be impossible without a computer.
A computer like this is often referred to as an embedded computer. An embedded computer is differentiated from a personal computer because it is essentially static in its function. While a personal computer, or some cellular telephones, or some personal organizers are able to have new software installed, and make use of a wide range of features, an embedded computer usually has only a few purposes, which are relatively fixed once the computer is manufactured.
Embedded systems vary in the amount of change that can happen to them after production. An MP3 player, for example, is an embedded computer, but can have quite a bit of interaction and changes made to it. It may allow the user to alter the colors used, change the clock, update firmware, and change the songs or playlists in memory. An embedded computer within a traffic light, to take another example, is probably quite fixed. It is set to respond to a few certain programs — time of day, a trigger when a car approaches, and perhaps input from a central database in the case of more advanced systems. These programs are not built for interactivity, and will likely never be changed over the system’s life.
ns more than simply the Macs and PCs we are familiar with. A computer is, at its most basic, a machine which can take instructions, and perform computations based on those instructions.
It is the ability to take instructions — often known as programs in the parlance of computers — and execute them, that distinguishes a computer from a mechanical calculator. While both are able to make computations, a calculator responds simply to immediate input. In fact, most modern calculators are actually computers, with a number of pre-installed programs to help aid in complex tasks.
, and mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century (1940–1945). Originally, they were the size of a large room, consuming as much power as several hundred modern personal computers (PCs). Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space. Simple computers are small enough to fit into mobile devices, and can be powered by a small battery. Personal computers in their various forms are icons of the Information Age and are what most people think of as "computers". However, the embedded computers found in many devices from MP3 players to fighter aircraft and from toys to industrial robots are the most numerous.The first use of the word "computer" was recorded in 1613, referring to a person who carried out calculations, or computations, and the word continued to be used in that sense until the middle of the 20th century. From the end of the 19th century onwards though, the word began to take on its more familiar meaning, describing a machine that carries out computations.

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