What is Computer?

Computers are growing in popularity day by day. It is the most powerful tool man has ever invented. Computers have made a great impact on our every day life. Earlier computers were used for complex calculations and used only by scientists and engineers. The trend then was to design large and powerful computers to handle large data and solve complex problems. They were very costly and hence only large organizations could afford them. Technical developments in design and fabrication of semi conductor devices, today, have made possible manufacture of powerful micro computers. The cost of these computers have come down drastically so that even small organizations and individuals can afford them. These computers being very fast can be used not only for computation, but also to store and retrieve information, to control certain processes and machines, to measure and display certain quantities, to send or receive e-mail, to search the web, to see a movie and so on. We can also store, retrieve and transmit text, graphics, pictures and sound. Within limitations imposed by their designers, computers can do whatever they are programmed to do. They cannot "think" for themselves, but their method of dealing with the problem is similar in many respects to the human thought process. 

Consider a simple task like deciding wheather to take an umbrella when you go to work in the morning. You open the door and look at the sky. You take that information into your brain and store it. You may not be aware of it, but you are. You then compare it to previous experiences and decide; if it is raining or very cloudy, an umbrella is needed. So you pick up one and go out. This can be summarized in more general terms as follows.

1. You retrieve information through senses: feeling, smelling, tasting, hearing or touching.

2. You keep the information in your memory. 

3. Other information about similar circumstances are retrieved from another part of your memory. 

4. You take a decision logically. for example, comparing two pieces of information. 

5. You act on the basis of the decision arrived at, for example, speak, walk, use your hands or look for more information. 

Though it may seem silly to break down each action to this extent, this is exactly how a computer works. It gets data or information through some form of input. This information is stored in memory. But, unlike the human brain which usually remembers all the information (through the eyes, ears, nose, tongue and touch), the computer retains only the information it has been programmed to store. Any other information is lost. If a computer has been programmed to compare two bits of data, it will do so and take an appropriate decision. The result is transmitted to the output unit of the computer. 

A computer, therefore, follows a series of instructions that have been programmed into its memory by the user and operates on data that are presented to it by the user. The data input may be in the form of: 

♦ Typed (linguistic) data or instructions in computer's language. The linguistic raw data can be numeric. alphabetic or alphanumeric. 

♦ It may include audible, visual or audio-visual analogic data. 

A computer can process information only in accordance with the program put into it. It can process data only according to the instructions given in the program, but it can not think by itself and cannot deal with incomplete information, erroneous data etc.. as it has no common sense. The programmer should anticipate such conditions and program accordingly. What makes today's computers so valuable is that they are very fast and reliable. Even the low cost personal computers can perform several million operations per second and can do so for years. Also they can store huge amounts of information and move this information from one place to another at incredible speeds. In simple words, a computer is an electronic device which processes information, based upon the instructions provided and generates the desired output. Like any other system, a computer also requires an input which is processed to produce the desired output. Computer needs two kinds of inputs. One, the basic or raw data and two, a set of instructions containing the methodology to process this data. This set of instructions is called a program or software.