Introduction to Computers

What is a computer?

A computer is an electronic device which consists of hardware and software. Hardware components describe the physical parts of the computer and software controls hardware and run the operating system, different programs & applications like  Microsoft Windows, Microsoft Word, Microsoft Excel etc.

Basic components of Computer

1. Input Unit –The devices which are used to input the data and programs in the computer are known as “Input Devices”. Input unit accepts instructions and data from the user and converts these instructions and data in computer acceptable format which are sent to the computer system for processing.

 Examples of Input devices are –

1.  Keyboard
2. Mouse
3.  Scanner
4.  Track ball
5. Light pen
6.  Character Reader (OCR)
7.  Barcode Reader
8.  Voice Input System
9.  Digital Camera

 2. Output Unit — Output Device produces the final results of the computer into human understandable form. Output unit accepts the results produced by the computer which are in coded form and it converts these coded results to human readable form.

                  Examples of output  devices are –

1. Monitor: 
2. Printer
3. Touch screen
4. Plotter

3. Storage Unit – The data and instructions that are entered into the computer system through input units have to be stored inside the computer before the actual processing starts. Similarly, the results produced by the computer after processing must also be kept somewhere inside the computer system before being passed on to the output units. The Storage Unit or the primary / main storage of a computer system is designed to do all these things. It provides space for storing data and instructions, intermediate results and for the final results.

4. Central Processing Unit (CPU) –The main unit inside the computer is the CPU. This unit is responsible for all events inside the computer. It consists of a Control Unit and Arithmetic and Logic unit. The CPU is the brain of any computer system. In a human body, all major decisions are taken by the brain and the other parts of the body function as directed by the brain. Similarly, in a computer system, all major calculations and comparisons are made inside the CPU and it activates and controls the operations of other units like Hard disk, Printer etc. of a computer system.

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Arithmetic and Logic Unit (ALU) : The arithmetic and logic unit (ALU) is the part where actual computations take place. It consists of circuits that perform arithmetic operations (e.g. addition, subtraction, multiplication, division over data received from memory and are capable of comparing numbers (less than, equal to, or greater than etc).

Control Unit: The control unit acts as a central nervous system for the components of the computer. It manages and coordinates the entire computer system. It obtains instructions from the program stored in main memory, interprets the instructions, and issues signals that cause other units of the system to execute them. The control unit directs and controls the activities of the internal and external devices.