To perform computer functionalities, we need some hardware and software. In a general way computer is an electronic device which perform particular tasks. It takes input and processes it to produce an output.
Primarily there are three main components of a digital computer.-Input Unit, Processing Unit and, Output Unit.
Input Unit-
It takes different types of input data from various input devices like-keyboard, mouse, light pen, scanner, MICR, Bar Code Reader, etc. Whenever you want to instruct anything to a computer, input device (s) is (are) needed. If you want to write an application on a computer, you need an input device called “KEYBOARD”.
List of input devices-
• Keyboard
• Mouse
• Light pen
• Trackball
• Scanner
• Microphone
• Optical Character Reader (OCR)
• Optical Mark Reader (OMR)
Details about some frequently used input devices-
Keyboard-
Keyboard is a frequently used input device. A keyboard is just like a traditional typewriter, although keyboard has some additional keys used for performing additional functions.
Mouse-
This is a commonly used pointing device. A mouse can be used to control the position of the cursor on the screen, but it cannot be used to enter text or any data into the computer. Douglas Engelbart called the father of mouse and invented it in 1963.There are basically three kinds of mouse- Mechanical Mouse, Optical Mouse, and Cordless Mouse.
Scanner-
A scanner is an input device just like a photocopy machine. It is used when a paper has some information and it is to be transferred to the computer for further manipulation. The scanner captures images from the source, which are then converted into a digital form that can be stored on the disk.
Processing Unit-
The Processing unit is also called a Central Processing Unit (CPU). CPU is the brain of your computer. It performs all types of data processing operations and stores data & intermediate results for a while (during processing). It also controls the operation of all parts of the computer system. In general terms, CPU can be understood as the following-
· Control Unit (C) - It controls the various component of a computer.
· Arithmetic and Logic Unit (ALU) - This subunit of the CPU performs all the arithmetic and logical operations such as- addition, subtraction, multiplication, division, and comparison.
Output Unit-
The processed data is called output. After processing, either the results are stored in the memory or sent to the output unit. Some examples of different output devices are- CRT (Cathode Ray Tube) monitor, LCD (Liquid Crystal Display) monitor, LED (Light Emitting Diode) monitor, printer, speaker, screen projector, plotter, etc.
Monitor-
A monitor is a commonly used output device which displays information in a similar way to that of a television screen. Generally, the size of a monitor is 19-inch, 20 inch and 21 inches.
Printer-
A printer is a hard copy output device i.e. it provides the output in a hard copy/printed form. There are two types of computers- Impact Printer and Non- impact printers.
Impact Printers– refers to all those printers whose printing heads touches the paper, for e.g. dot matrix printer.
Non- Impact Printer– refers to all those printers whose printing heads do not touch the paper, for e.g. laser and inkjet printer.