Stored program architecture

The defining feature of latest computers which distinguishes them from all other machines is that they can be programmed. That is to say that a set of instructions (the program) can be given to the computer and it will store them and carry them out at some time in the future.

In most cases, computer instructions are simple: add one number to another, move some data from one place to another, send a message to some external device, etc. These instructions are read from the computer's memory and are useually carried out (executed) in the order they were given. However, there are geneally specialized instructions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called as "jump" instructions (or branches).

First Programmable machine computer

In 1837, Charles Babbage was the initialyt to conceptualize and design a fully programmable mechanical computer that he called "The Analytical Engine". Due to small finance, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine.

Large-scale automated data processing of punched cards was performed for the U.S. Census in 1890 by tabulate machines designed by Herman Hollerith and created by the Computing Tabulating Recording Corporation, which later became IBM. By the end of the 19th century a number of technologies that would later prove useful in the realization of user computers had begun to appear: the punched card, Boolean algebra, the vacuum tube (thermionic valve) and the teleprinter.

During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical representation of the problem as a basis for computation. However, these were not programmable and usually lacked the versatility and accuracy of modern digital computers.

History of computing

It is difficult to identify any one device as the earliest computer, partly because the term "computer" has been subject to changeable interpretations over time.

Originally, the term "computer" referred to a person who performed numerical calculations (a human computer), often with the aid of a mechanical calculating device. Examples of early perfunctory computing devices included the abacus, the slide rule and arguably the astrolabe and the Antikythera mechanism (which dates from about 150-100 BC). The end of the center Ages saw a re-invigoration of European mathematics and engineering, and Wilhelm Schickard's 1623 device was the first of a number of mechanical calculators constructed by European engineers.

However, none of those devices fit the current definition of a computer because they could not be programmed. In 1801, Joseph Marie Jacquard made an development to the textile loom that used a sequence of punched paper cards as a template to allow his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the improvement of computers because the use of punched cards to define woven patterns can be viewed as an early, even though limited, form of programmability.

Computer

A computer is a machine which manipulates data according to a list of instructions which makes it an best example of a data processing system.

Computers take many part of physical forms. Early electronic computers were the size of a large room, consuming as much power as several hundred present personal computers. Modern computers are based on comparatively tiny integrated circuits and are millions to billions of times more capable while occupying a little of the space. Today, simple computers may be made small sufficient to fit into a wrist watch and be powered from a watch battery. Personal computers in different forms are icons of the information age and are computer in use today is by remote the embedded computer. Embedded computers are small, simple devices that are often used to manage other devices — for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and even children's toys.