The word ‘computer’ literally means to ‘compute’ or to ‘calculate’. Every type of job relies upon getting information from the computers and then using and managing it. A computer receives data and instructions through input devices, which get processed in Central Processing Unit, and the result is shown through output devices. The primary memory and secondary memory are used to store data inside the computer.
Input devices transform data from the user into a form that a computer system can process. Some popular input devices include keyboard, mouse, scanner, microphone, web cam etc. A standard computer keyboard has 104 keys. Mouse controls the movement of the cursor or pointer on a display screen. Light pen is a light-sensitive input device, which allows the user to point towards the displayed objects or draw on the screen with greater positional accuracy. Touch screen helps a user to interact with the computer by touching the icons, the buttons, the pictures or the words on the computer screen. Smart Card Reader is used to access the microprocessor of a smart card. It is used in companies/organisations for strong security authentication. Biometric Sensor is used to recognise individuals based on physical or behavioural traits.
Output devices are used to display results on video display or are used to print the result. These can also be used to store the result for further use. Some popular output devices include monitor, plotter, printer etc. Monitor / Visual Display Unit is an output device that gives output in the visual form. LCD (Liquid Crystal Display) uses the light modulating properties of liquid crystals. Dot Matrix Printer prints characters by striking an ink soaked ribbon against the paper. Plotter is used to print graphics. It is usually used for Computer Aided Design (CAD) and Computer Aided Manufacture (CAM) applications such as printing out plans for houses.
Central Processing Unit has two main components, Arithmetic Logic Unit and Control unit. Control unit directs the sequence of operations. Memory is a collection of storage cells capable of storing binary information. Computer’s memory stores data that is accessed by the CPU. The memory of a computer is often called main memory or primary memory. The memory unit is divided into: RAM and ROM.