Input devices

 Input Devices:  

The device through which we enter data and instruction into computer is called input device. There are many devices for input. These devices of a digital Computer are responsible for accepting programs and data from the outside world, feeding it to the Computer, and storing it into the Computer memory. These devices work under the control of Microprocessor. Some of the famous Input devices are as below Keyboards, mouse, scanners, microphone, video camera, touch screen, and optical scanning.  

KEYBOARD:-  

lt is a very common input device that helps in keying-in the required information into the Computer. Keyboard can be used effectively to communicate with the Computers but it is very slow input device. The keyboard is just like a typical typewriter in shape but enhanced than that. It consists of normal Alphabetic, numeric, functions, and other special characters or control keys, which are not available in a typewriter.  

POINTING DEVICES:  

An input device used to control a pointer on the screen is called poi nting devices. A pointer is a small symbol that appears on the screen in graphical user interface. Some  example of pointing devices is Mouse, Track ball, Joy stick etc.   

a) MOUSE:-  

A Mouse is a quick input device and is very small in size. Mouse is moved on a flat  surface to control the movement of the cursor (pointer) on a screen. A mouse usually  has two or three buttons. These buttons are used to perform different task.  

b) THE TRACKBALL:  

Track Ball is pointing devices most often used in the place of the mouse. A trackball is a stationary (motionless) device related to the mouse. It has a ball on the top and you can   roll the ball directly with your hand. The trackball is used in laptop computer. There is no  need of mouse pad for track ball.  

TOUCH SENSITIVE SCREENS: 

 Touch screen is a video display screen that receives input from the touch of finger. The  screen is covered with a plastic layer. There are invisible beam of infrared light behind  the screen. The user enters data by touching icons or menus on the screen. Most touch screen computer use sensor to detect touch of a finger  

PEN-BASED COMPUTING (LIGHT PEN)   

The pen-based devices use photoelectric circuitry to enter data into the computer  through a video screen. A user can write on the video display, the light-sensitive pen  sends information to the computer when user touches the pen on certain areas of a  specially designed screen. Light pen is usually used by engineer, graphic designer, and illustrator.  

VOICE RECOGNITION   

Voice recognition device is used- to directly i convert spoken data into electronic form into a computer system. Voices recognition and voice response is the easiest method   for data entry and conversational. The microphone is attached to the computer with the  help of sound card. The capability of a computer to distinguish spoken words is called voice recognition or speech recognition. Voice input is faster way of entering data. Many word processing applications provide the facility of voice input. The user speaks in   microphone and the application software writes the spoken words as a text. Speech microprocessors can be found in toys, calculators, appliances, automobiles, and a variety of other consumer, commercial, and industrial products.  

SCANNER:  

Scanner is Optical character recognition equipment that can read special-purpose  characters and codes. Scanner provides a method of direct input of data from sources   documents into a computer system. There are many type of optical reader, but they all use photoelectric devices to scan the characters being read. Reflected light pattern of  the data are converted into electronic impulses, which are then accepted as input into  the computer system. OCR-based optical scanning systems are used extensively in the credit card billing operations of credit' card companies, bank, and oil companies.  

MICROPHONE:  

It is an input device that is used for the input of voice in place of using the keyboard and    mouse. Special software is used to convert voice into text. This- requires fast   processing and a lot of memory and will become more common as the tec lino logy    improves. The microphone converts audio signals into digital form.  

VIDEO CAMERAS:  

Video cameras are an input device that is able to capture images of any type data. Most scanners incorporate a special sort of camera made up of Charged-Coupled Devices  (CCDs). Each CCD receives light from the image and the light generates an electrical  charge. This means that light areas or dots of the image are represented by charged   cells and dark areas by uncharged cells.