The word “computer” comes from the word “compute”, which means, “to calculate”. Hence, people usually use a computer to be a calculating device that can perform arithmetic operations at high speed. In fact, the original objective for inventing a computer was to create a fast calculating machine. However, more than 80% of work done by computers today is of non-mathematical or non-numerical nature. Hence, to define computer merely as a calculating device is to ignore over 80% of its functions. More accurately, we can define a computer as a device that operates upon data.
Data can be anything like bio-data, hence computer is used for short listing candidates for recruiting; marks obtained by students in when used for preparing results; details (name, age, sex, etc.) of passengers when used for or railway reservations: or number of different parameters when used for solving scientific problems, etc. Hence, data comes in various shapes and sizes depending upon the type of computer application. A computer can and retrieves data as and when desired. The fact that computers process data is so fundamental that have started calling it a data processor.
The name data processor is more inclusive because modern computers not only compute in the usual sense but also perform other functions with data that flows to and from them. For example, data processors may gather data from various incoming sources, merge (process of mixing or putting together) them all, sort (process of arranging in some of sequence— ascending or descending) them in the desired order, and finally print them in desired format. Notice that none of these operations involves arithmetic computations in the usual sense but a computer is the most suitable device for performing them.
People usually consider a computer to be a calculating device that can perform arithmetic operations at high speed. It is also known as a data processor because it not only computes in the usual sense but also performs other functions with the data. The activity of processing data using a computer is called data processing. Data processing consists of three sub-activities: capturing input data, manipulating the data, and managing output results. As used in data processing, information is data arranged in an order and form that is useful to people receiving it. Hence, data is raw material used as input to data processing and information is processed data obtained as output of data processing.
1.1 Characteristics of Computers
Increasing popularity of computers has proved that it is a very powerful and useful tool. The power and useful of this popular tool are mainly due to its following characteristics:
- An automatic machine works by itself without human intervention. Computers automatic machines because once started on a job, they carry out the job (normally without a human assistance) until it is finished. However, computers being machines cannot start themselves and cannot go out and find their own problems and solutions. We need to instruct a computer using coded instructions that specify exactly how it will do a particular job. Some of the other characteristics of computers (such as speed and accuracy) are because they are automatic and work on a problem without any human intervention.
- Speed. A computer is a very fast device. It can perform in a few seconds, the amount of work that a human being can do in an entire year if he/she worked day and night and did nothing else. In other words, a computer can do in a few minutes what would take a man his entire life time while talking about the speed of a computer we do not talk in terms of seconds or even milliseconds (10–3) but in terms of microseconds (106), nanoseconds (10–9), and even picoseconds (10–12). A powerful computer is capable of performing several billion (l09) simple arithmetic operations per second.
- Accuracy. In addition to being very fast, computers are very accurate. Accuracy of a computer is consistently high and the degree of its accuracy depends upon its design. A computer performs even calculation with the same accuracy. However, errors can occur in a computer. These errors are mainly due to human rather than technological weaknesses. For example, errors may occur due to imprecise thinking by a programmer or incorrect input data. We often refer to computer errors caused due to incorrect input data or unreliable programs as garbage-in-garbage-out (GIGO).
- Diligence. Unlike human beings, a computer is free from monotony, tiredness, and lack of concentration. It can continuously work for hours without creating any error and without grumbling. Hence, computers score over human beings in doing routine type of jobs that require great accuracy. If ten million calculations have to be performed, a computer will perform the last one with exactly the same accuracy and speed as the first one.
- Versatility. Versatility is one of the most wonderful things about a computer. One moment it is preparing results of an examination, next moment it is busy preparing electricity bills, and in between, it may be helping an office secretary to trace an important letter in seconds. All that is required to change its talent is to slip in a new program (a sequence of instructions for the computer) into it. In brief, a computer is capable of performing almost any task, if the task can be reduced to a finite series of logical steps.
- Power of Remembering. As a human being acquires new knowledge, his/her brain subconsciously selects what it feels to be important and worth retaining in memory. The brain relegates unimportant details to back of mind or just forgets them. This is not the case with computers. A computer can store and recall any amount of information because of its secondary storage (a type of detachable memory) capability. It can retain a piece of information as long as a user desires and the user can recall the information whenever required. Even after several years, a user can recall exactly the same information that he/she had stored in the computer several years ago. A computer forgets or looses creation information only when a user asks it to do so. Hence, it is entirely up to the user to make a computer retain or forget some information. No IQ. A computer is not a magical device. It possesses no intelligence of its own. Its IQ is zero, at least until today. It has to be told what to do and in what sequence. Hence, only a user determines—at tasks a computer will perform. A computer cannot take its own decision in this regard. No Feelings. Computers are devoid of emotions. They have no feelings and no instincts because they are Machines. Although men have succeeded in building a memory for computer, but no computer processes the equivalent of a human heart and soul. Based on our feelings, taste, knowledge, and experience we often make certain judgments in our day-to-day life whereas, computers cannot make judgments on their own. They make judgments based on the instructions given to them in the form of programs that are written by us (human beings).