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A computer is an electronic machine capable of accepting data, processing data arithmetically and logically, producing output from the processing, and storing the results for future use.

The first three operations in the information processing cycle which include input, process, and output are performed to process data into information, while the fourth operation, storage refers to a computer's electronic reservoir capability


A computer is an electronic device, operating under the control of instructions (software) stored in its own memory unit, that can accept data (input), manipulate data (process), and produce information (output) from the processing. Generally, the term is used to describe a collection of devices that function together as a system.

Data and Information
Data : Raw facts that are not yet processed. include numbers , letters and symbols etc.

Information : This is the end product of data processing stages which have been transformed and have clear meaning to the user.

    Components of computer
    Computer components are divided into major categories :-
  1. Hardware
  2. Software
  3. Live ware (People)

  1. Hardware : Is the machine itself and its connected devices such as Monitor, Motherboard, Mircoprocessor, Primary Storage (RAM) , Expansion cards, Power supply, Optical disc drive, Secondary Storage (Hard disk), System Case, Keyboard, Mouse etc.
  2. Software : Are the set of programs that make use of hardware for performing various functions. So, without softwares computer system will not be able to work.
  3. Live ware : These can be termed as the people and other consumable which make use of the computer.

    Categories and Classification of Computers (Types of a computers)
    Computers are classified into different types depending on the memory size, cost and processing speed.
  1. Classification by size / capacity
    1. Mainframe computers
    2. Mini computers
    3. Micro computers
    4. Super computers
  2. Classification by function (process)
    1. Analog computers (Special purpose)
    2. Digital computers (General purpose )
    3. Hybrid computers
  3. By technological generation (Computer Generations)
    1. First technology uses vacuum tube
    2. Second technology uses transistors, capacitors, resistors.
    3. Third technology uses integrated circuits - ICs
    4. Fourth Generation uses Processor
    5. Fifth Generation uses Artificial Intelligence

    Advantages of using a computer
  1. Speed : Can process work within a short time that could be done by so many people and therefore it is time saving
  2. Accuracy : The way you type in data is the way it appears
  3. Storage : It can store a large information in a limited space
  4. Secrecy : Information is fairly protected if the computer is well managed
  5. Reference : One can store documents for future use
  6. Security : Information can be prevented from being accessed by the unauthorized personnel through the use of password
  7. Quality of presentation : Work in a computer can be presented in various ways and can as well be transmitted easily. Also font style are readable than human writings.
  8. Entertainment tool :It can be used as an entertainment tool
  9. Higher memory capacity : It has a higher memory compared to human beings

    Disadvantages of using a computer
  1. Unemployment : Only the skilled continues with job. It does work that could be instead done by many people manually.
  2. Cost : The cost of running a computer or any associated information system is high especially to small business operators
  3. Health hazard : Can cause eye problems
  4. Virus attack : This may cause the loss of vital information stored in computer at any time
  5. Expensive to hire : Computers need experts for maintenance which is expensive to hire
  6. Loss of information : If not well managed is easy.

    Application of a computer
  1. In institutions :It is used in teaching and learning process
  2. Offices :It is used for data management
  3. Hospitals :It is used for monitoring patients and records management
  4. Airports :It is used for aircrafts management
  5. Factories or industries :It is used for driving machines and car assembles (robots)
  6. Supermarkets :It is used for stock control
  7. Banks :It is used for deposits, withdrawals, balances etc.
  8. Transport :It is used for monitoring vehicle traffic on a busy town , aircraft
  9. Communication :It is used for message transmission from one person to another efficiently and effectively
  10. Law enforcement agencies :information held in computers such as fingerprints, photographs and other identification details helps law enforcers to carry out criminal investigations speedily
  11. Domestic and entertainment : It is used for creating movies etc.
  12. Library services : In computerized library, a computer enables library personnel to easily access and keep update records of book.
  13. Cartoon Film Production
  14. Space Research
  15. Payment of electricity and telephone lines
  16. Information Technology
  17. Etc.

    Operations or functions of a computer
    A computer performs five major operations or functions irrespective of its size and make. These are :-
  1. It accepts data or instructions as input
  2. It stores data and instruction
  3. It processes data as per the instructions
  4. It controls all operations inside a computer and
  5. It gives results in the form of output

    Characteristics of a computer
    The characteristics of computers that have made them so powerful and universally useful are speed, accuracy, diligence, versatility and storage capacity.
  1. Speed : Computers work at an incredible speed. A powerful computer is capable of performing about 3-4 million simple instructions per second.
  2. Accuracy : In addition to being fast, computers are also accurate. Errors that may occur can almost always be attributed to human error (inaccurate data, poorly designed system or faulty instructions/programs written by the programmer)
  3. Diligence : Unlike human beings, computers are highly consistent. They do not suffer from human traits of boredom and tiredness resulting in lack of concentration. Computers, therefore, are better than human beings in performing voluminous and repetitive jobs
  4. Versatility : Computers are versatile machines and are capable of performing any task as long as it can be broken down into a series of logical steps. The presence of computers can be seen in almost every where like Railway and Air reservation, Banks, Hotels, Weather forecasting and many more.
  5. Storage Capacity : Today's computers can store large volumes of data. A piece of information once stored in the computer, can never be forgotten and can be retrieved almost instantaneously.

    Limitations of a computer
  1. Computer needs clear and complete instructions to perform a task accurately. If the instructions are not clear and complete, the computer will not produce the required result.
  2. Computer can not think.
  3. Computer can not learn by experience.