Input and output device.docx

Input device From Wikipedia, the free encyclopedia In computing, an input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or other information appliance. Examples of input devices include keyboards, mice, scanners, digital cameras andjoysticks. Many input devices can be classified according to: 

modality of input (e.g. mechanical motion, audio, visual, etc.)

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the input is discrete (e.g. key presses) or continuous (e.g. a mouse's position, though digitized into a discrete quantity, is fast enough to be considered continuous)

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the number of degrees of freedom involved (e.g. two-dimensional traditional mice, or three-dimensional navigators designed for CAD applications)

Pointing devices, which are input devices used to specify a position in space, can further be classified according to: 

Whether the input is direct or indirect. With direct input, the input space coincides with the display space, i.e. pointing is done in the space where visual feedback or the pointer appears. Touchscreens and light pens involve direct input. Examples involving indirect input include the mouse and trackball.

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Whether the positional information is absolute (e.g. on a touch screen) or relative (e.g. with a mouse that can be lifted and repositioned)

Direct input is almost necessarily absolute, but indirect input may be either absolute or relative.[clarification needed] For example, digitizing graphics tabletsthat do not have an embedded screen involve indirect input and sense absolute positions and are often run in an absolute input mode, but they may also be set up to simulate a relative input mode like that of a touchpad, where the stylus or puck can be lifted and repositioned. Input and output devices make up the hardware interface between a computer and a scanner or 6DOF controller. Keyboards[edit] Main article: Computer keyboard

A 'keyboard' is a human interface device which is represented as a layout of buttons. Each button, or key, can be used to either input a linguistic character to a computer, or to call upon a particular function of the computer. Traditional keyboards use springbased buttons, though newer variations employ virtual keys, or even projected keyboards. Examples of types of keyboards include: 

Computer keyboard

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Keyer

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Chorded keyboard

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LPFK

Pointing devices[edit] Main article: Pointing device

A computer mouse Keyboard devices are the most commonly used input devices today. A pointing device is any human interface device that allows a user to input spatial data to a computer. In the case of mice and touch screens, this is usually achieved by detecting movement across a physical surface. Analog devices, such as 3D mice,joysticks, or pointing sticks, function by reporting their angle of deflection. Movements of the pointing device are echoed on the screen by movements of the pointer, creating a simple, intuitive way to navigate a computer's GUI. High-degree of freedom input devices[edit] Some devices allow many continuous degrees of freedom as input. These can be used as pointing devices, but are generally used in ways that don't involve pointing to a location in space, such as the control of a camera angle while in 3D applications. These

kinds of devices are typically used in CAVEs, where input that registers 6DOF is required. Composite devices[edit]

Wii Remote with attached strap Input devices, such as buttons and joysticks, can be combined on a single physical device that could be thought of as a composite device. Many gaming devices have controllers like this. Technically mice are composite devices, as they both track movement and provide buttons for clicking, but composite devices are generally considered to have more than two different forms of input. 

Game controller

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Gamepad (or joypad)

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Paddle (game controller)

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Wii Remote

Imaging and video input devices[edit]

Microsoft Kinect sensor seen here on aTV, works by detecting human motion visually Video input devices are used to digitize images or video from the outside world into the computer. The information can be stored in a multitude of formats depending on the user's requirement.

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Digital camera

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Digital camcorder

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Portable media player

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Webcam

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Microsoft Kinect Sensor

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Image scanner

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Fingerprint scanner

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Barcode reader

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3D scanner

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3D Printer

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Laser rangefinder

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Eye gaze tracker

Medical Imaging 

Computed tomography

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Magnetic resonance imaging

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Positron emission tomography

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Medical ultrasonography

Audio input devices[edit] In the fashion of video devices, audio devices are used to either capture or create sound. In some cases, an audio output device can be used as an input device, in order to capture produced sound. 

Microphone

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MIDI keyboard or other digital musical instrument

Output device From Wikipedia, the free encyclopedia An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) which converts the electronically generated information into humanreadable form.[1][2] Display devices[edit] A display device is an output device that visually conveys text, graphics, and video information. Information shown on a display device is called soft copybecause the information exists electronically and is displayed for a temporary period of time. Display devices include CRT monitors, LCD monitors and displays, gas plasma monitors, and televisions.[3] Input/output[edit]

Inputs are the signals or data received by the system, and outputs are the signals or data sent from it. There are many input and output devices such as multifunction printers and computerbased navigation systems that are used for specialised or unique applications.[1] In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it. Types of output[edit] Some types of output are text, graphics, tactile,[4] audio, and video. Text consists of characters (letters, numbers, punctuation marks, or any other symbol requiring one byte of computer storage space) that are used to create words, sentences, and paragraphs. Graphics are digital representations of nontext information such as drawings, charts, photographs, and animation (a series of still images in rapid sequence that gives the illusion of motion). Tactile output such as raised line drawings may be useful for some

individuals who are blind. Audio is music, speech, or any other sound. Video consists of images played back at speeds to provide the appearance of full motion. [3] Graphics[edit]

Graphical output displayed on ascreen. A digital image is a numeric representation of an image stored on a computer. They don't have any physical size until they are displayed on a screen or printed on paper. Until that point, they are just a collection of numbers on the computer's hard drive that describe the individual elements of a picture and how they are arranged. [5] Some computers come with built-in graphics capability. Others need a device, called a graphics card or graphics adapter board, that has to be added.[6] Unless a computer has graphics capability built into the motherboard, that translation takes place on the graphics card.[7] Depending on whether the image resolution is fixed, it may be of vector or raster type. Without qualifications, the term "digital image" usually refers to raster images also called bitmap images. Raster images that are composed of pixels and is suited for photo-realistic images. Vector images which are composed of lines and co-ordinates rather than dots and is more suited to line art, graphs or fonts.[5] To make a 3-D image, the graphics card first creates a wire frame out of straight lines. Then, it rasterizes the image (fills in the remaining pixels). It also adds lighting, texture and color.[7] Tactile[edit] Haptic technology, or haptics, is a tactile feedback technology which takes advantage of the sense of touch by applying forces, vibrations, or motions to the user.[8] Several printers and wax jet printers have the capability of producing raised line drawings. There are also handheld devices that use an array of vibrating pins to present a tactile outline of the characters or text under the viewing window of the device.[4]

Audio[edit] Speech output systems can be used to read screen text to computer users. Special software programs called screen readers attempt to identify and interpret what is being displayed on the screen[9] and speech synthesizers convert data to vocalized sounds or text.[6] Examples[edit] These examples of output devices also include input/output devices.[10][11] Printers and visual displays are the most common type of output device for interfacing to people, but voice is becoming increasingly available.[12] 

Speakers

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Headphones

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Screen (Monitor)

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Printer

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Voice output communication aid

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Automotive navigation system

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Braille embosser

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Projector

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Plotter

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Television

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Radio