What is input device

The hardware devices through which we can send the data and instructions to the computer are known as input devices. The input devices are simply any kind of device through which send our queries to the computer which further goes to CPU for processing and comes back as a output. These devices are comparatively more cheaper in comparison to output devices.  Following are some examples of the most common and popular input devices. 

a. Keyboard 

A Keyboard text input device which is used to enter data directly into the computer. It resembles a typewriter console. While typing on a computer using keyboard, we will notice a flashing line on the screen which is called cursor. When a key on a keyboard is pressed, the character is displayed at the point where the cursor is flashing and the cursor moves one position forward. When the key is pressed and the information is passed to computer the computer only understands the equivalent ASCII (American Standard Code for Information Interchange ) value of the key pressed. A keyboard contains alphabets, digits, special characters and function keys. The most commonly used keyboard is QWERTY keyboard which contains 104 key including 12 function keys.

b. Mouse

Mouse is a pointing input device. It is a hand held device that points on a screen when moved across  a flat surface. While we  move the mouse around the desktop, the rubber coated ball on the bottom of the mouse moves. The bus movement is translated into electronic signal that tells the computer how to move the cursor in the screen. A mouse has one or more buttons on the surface used to make selection from the menus on the screen or for control purpose.

c. Scanner

Scanner is a kind of input device which is capable of entering information directly into the computer without typing any  information or data. It provides fast and more accurate data entry. A scanner scans an image and transforms the image to the code  used by a computer. Scanners come in various shapes and sizes.

d. Trackball

The trackball is also a painting input device like mouse which consists of a movable ball in a socket. The ball can be rolled by users' finger or palm to move the pointer on the screen. As the ball is moved the pointer moves on the screen in the same  direction to select objects and menus. Trackballs are mostly used in portable computers such as laptops, palmtops, notebooks, etc.

e. Touch pad

Touch pad is a touch sensitive pad that is used as pointing input device. We can point the objects on the screen and give commands to the computer by putting our fingers on the touchpad. The touch pad also used with portable computers such as laptops, palmtops, notebooks, etc. 

f. Joystick

Joystick is a screen pointing input device. A joystick consists of vertical stick and spring. The spring is used to return the joystick to its central position. The stick can be moved in any direction, left, right, up and down or four diagonally directions and the switch detects in which direction the stick is being moved. The joystick is mostly used in video games or in flight simulation to train pilots on the ground. 

g. Bar Code Reader (BCR) 

Data coded in the form of small lines (bars) are knows as bar codes. Bar code data represent the alphanumeric data by a combination of adjacent vertical lines (bars) by varying their width and spacing between them. They are used for unique identification of all types of goods, books, postal packages etc. A bar code reader is a device used for reading bar coded data. It scans a bar code image and converts it into alphanumeric values. A bar code reader uses laser-beam scanning technology. Different bar codes having different patterns of bars reflect the beam in different ways that is sensed by a light sensitive detector. Reflected light patterns are converted into electrical pulses and then transmitted to a recognition logic circuit that converts into alphanumeric values. 

h. Digital camera 

A digital camera is a camera that takes video or photographs and inputs to the computer in the digital format. At first, the photographs are stored in the camera's memory and then transferred to a computer through a cable. Then, we can edit those photographs according to our requirement. Most of the camera we use today are digital. This is one of the portable and useful devices specially while travelling and any special occasions. 

i. Microphone 

A microphone also known as mic is an input device that captures audio by converting sound waves into an electrical signal. This signal can be amplified as an analog signal or may be converted to a digital signal, which can be processed by a computer or other digital audio device. It is an input hardware originally invented by Emile Berlinerin in 1877 that allows computer users to input audio into their computers. It is widely used in voice chatting over the Internet and video conferencing. Microphone is specially used in messenger programs such as Yahoo! messenger, Windows live messenger and Skype. It is connected to a computer often using a USB port. 

j. Graphic Digitizer 

A graphic digitizer is an input device used for converting pictures, maps and drawings into digital form for storage in computers. A digitizer consists of a digitizing table t also called graphic tablet associated with a stylus. A digitizing tablet is a flat surface that contains hundreds of fine copper wires forming a grid. Each copper wire receives electric pulses. Digitizers are used commonly in the area of computer aided design (CAD) by architects and engineers to design` cars, buildings, medical devices, robots, etc. They are also used in the area of Geographic Information System (GIS). 

k. Touch screen 

A touch screen is a display device that allows the user to interact with a computer by using their finger. They are input devices which can be quite useful as an alternative to a mouse or keyboard for navigating a graphical user interface (GUI). Touch screens are used on a variety of devices such as computer and laptop monitors, smart phones, tablets, cash registers, and information kiosks. Some touch screens use a grid of infrared beams to sense the presence of a finger instead of utilizing touch-sensitive input. 

l. QR ( quick response ) code scanner: 

A QR is a type of barcode that contains a matrix of dots. It can be scanned using a QR scanner or a smart phone with built in camera. Once scanned, software on the devices converts the dots within the code into numbers or a string of characters. For example, scanning a QR code with the phone might open a URL in the phone's web browser. 

m. Web camera: 

A web camera is an input device with special camera which is used to take photos or videos and sends to the computer as input for processing. This device is mainly used in internet chatting and conversation. The web camera used in messenger programs such as yahoo messenger, windows live messenger and Skype. It is often connected with USB part of computer.

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