Basic Components of a Computer
Working of Computer
• Computers follow the basic principle of the Input-Process-Output (I-P-O) cycle.
• Input refers to data or instructions given to the computer.
• Output refers to the result given by the computer.
• Process refers to the work done by the computer to obtain the output.
• The input is given to the computer by means of input devices.
• Keyboard, Mouse, Scanner, Barcode reader, Web cam, and Microphone are some of the commonly used input devices.
Keyboard and Mouse Connectors
• The keyboard and mouse are connected to the computer by using PS/2, serial ports or a USB port.
• The PS/2 keyboard and mouse ports are 6-pin ports.
• To avoid confusion between the two ports, the system case usually has symbols and colour coding. The green colour port is used for mouse and the purple colour port is used for keyboard.
• A keyboard is used for typing text into the computer.
• A computer keyboard is similar to a typewriter keyboard but has some additional keys.
• The most commonly available computer keyboard has 104 keys.
• Based upon their connection to the motherboard, keyboards are classified into:
– PS/2 keyboard
– USB keyboard
– Wireless keyboard
• Mouse is an input device.
• It is used to point at and choose things displayed on the monitor.
• A mouse may have two or three buttons.
• The most commonly used ones have two buttons – left mouse button and right mouse button. The left button is the most frequently used button.
• Based upon their connection to the motherboard, mouse is classified into:
– PS/2 mouse
– Serial mouse
– USB mouse
– Wireless mouse
• Based on the technology used, mouse can be broadly classified into two categories. They are namely,
– Mechanical mouse
• Wireless Keyboard and Mouse
• Wireless keyboards and mice are powered by small, light weight batteries.
• The media used to connect to the computer can be through Radio Frequency (RF) waves, Infra Red (IR) signals or through Bluetooth or Industry standard RF.
• Wireless mouse or keyboard using infra red signals for communicating with the computer need to be in “line of sight” in order to work.
• Wireless mice or keyboard using radio frequencies for communication requires two components: a radio transmitter and a radio receiver.
• A scanner is a multimedia input device that uses light to read printed information including text, images and bar codes and transfers it to computer in digital format.
• Scanners can be categorised as:
– Flatbed scanners
– Sheet-fed scanners
– Handheld scanners
– Drum scanners
• Web camera or Webcam is a small camera attached to a computer.
• Webcams connected to PCs can act as Web-accessible cameras with certain software.
• Webcam can be used for one-to-one live video communication over the Internet, video conferencing and so on.
• It can capture short videos in predefined length or still images. The captured files can be saved locally and uploaded to an Internet server.
• A microphone is used to record voice or sound. This recorded sound can be stored in a computer in the form of digital signals.
• A barcode reader is an electronic device which optically scans a barcode and translates the data contained in the barcode pattern into data which can be used by a computer or other equipment.
• Barcode readers are mostly used in shopping malls.
• This device scans the barcodes present in the product labels to input the price of the products to the billing machine. It is very useful for quick billing.
• The system unit processes the input given to the computer and gives the output. This output can either be displayed on the monitor or printed on paper using a printer.
• The monitor looks like a television screen.
• It is also called Visual Display Unit (VDU)
• It is used to display information from the computer.
• There are coloured as well as black and white monitors.
• The monitor displays text and graphics.
• Based on the technology used, monitor is classified into two types. They are,
– Cathode Ray Tube (CRT) monitors
– Liquid Crystal Display (LCD) monitors
• A printer is used for transferring data from the computer to the paper.
• There are colour printers as well as black and white printers.
• The different types of printers are Dot Matrix Printers, Inkjet Printer and Laser Printers
Types of Printers
Dot Matrix Printer
Prints characters in the form of dots
Prints fully formed characters
Prints fully formed characters
Speed: 200-540 characters per second
Speed: 4-8 pages per minute
Speed: 4-20 pages per minute
Not very expensive
• A touch screen is a computer display screen that is sensitive to human touch.
• It allows the user to interact with the computer by touching pictures or words displayed on the screen.
• Touch screens are used to display the output information on the screen as well as to give input by touching the words or pictures on the screen. Thus it is an input/output device.
• Touch screens are normally used when information has to be accessed with minimum effort.