A QWERTY computer keyboard is a 104-key peripheral modeled after the typewriter keyboard.
Keyboards are designed for the input of text and characters and also to control the operation of a computer.
Physically, computer keyboards are an arrangement of rectangular or near-rectangular buttons, or "keys". Keyboards typically have characters engraved or printed on the keys; in most cases, each press of a key corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence; other keys do not produce any symbol, but instead affect the operation of the computer or the keyboard itself.
A mouse consists of a hand-held pointing device, designed to sit under one hand of the user and to detect movement relative to its two-dimensional supporting surface. In addition, it usually features buttons and/or other devices, such as "wheels", which allow the user to perform various system-dependent operations. Extra buttons or features can add more control or dimensional input. eTGHALLEM
1

A trackball is a pointing device consisting of a ball housed in a socket containing sensors to detect rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with their thumb, fingers, or the palm of their hand to move a cursor. Tracker balls are common on CAD workstations for ease of use and, before the advent of the touchpad, on portable computers, where there may be no desk space on which to use a mouse. Some clip onto the side of the keyboard and have integral buttons which have the same function as mouse buttons. Trackballs are sometimes seen on computerised special-purpose workstations, such as the radar consoles in an air-traffic control room or sonar equipment on a ship or submarine. Modern installations of such equipment may use mice instead, since most people now already know how to use one. However, military mobile antiaircraft radars and submarine sonars tend to continue using trackballs, since they can be made much more durable and are more fit for fast emergency use.
A touchpad is an input device commonly used in laptop computers. They are used to move the cursor, using motions of the user's finger. They are a substitute for a computer mouse. Touchpads vary in size but are rarely made larger than 20 cm² (8 in²). They can also be found in
PDAs. eTGHALLEM
2

Touchpads commonly operate by sensing the capacitance of a finger, or the capacitance between sensors. Capacitive sensors are laid out along the horizontal and vertical axes of the touchpad. The location of the finger is determined from the pattern of capacitance from these sensors. This is why they will not sense the tip of a pencil or other similar implement. Gloved fingers may be problematic (such as in a clean room environment) but can sometimes work. Moist or sweaty fingers can be problematic for those touchpads that rely on measuring the capacitance between the sensors.
The pointing stick (trademarked by IBM as the TrackPoint) is a pointing device (compare especially Touchpad) for laptops invented by research scientist
Ted Selker and is present on many brands of laptop, including
IBM's line of ThinkPad laptops
(now made by Lenovo) and on
Dell Latitudes under the name of
Track Stick. It has also been observed on computer mice and on some desktop keyboards.
The pointing stick has a replaceable rubber cap, traditionally red on the ThinkPad but also found in other colors on other machines. On a
QWERTY keyboard, the stick is embedded between the 'G', 'H' and 'B' keys, and the mouse buttons are placed just below the Spacebar.
The pointing stick operates by sensing applied force (hence it is also known as an isometric joystick), typically by measuring the resistance of a material. The velocity of the cursor eTGHALLEM
3

A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with the computer's CRT monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy. A light pen can work with any CRT-based monitor, but not with LCD screens, projectors or other display devices.
A light pen is fairly simple to implement. The light pen works by sensing the sudden small change in brightness of a point on the screen when the electron gun refreshes that spot.
By noting exactly where the scanning has reached at that moment, the X,Y position of the pen can be resolved. This is usually achieved by the light pen causing an interrupt, at which point the scan position can be read from a special register, or computed from a counter or timer. The pen position is updated on every refresh of the screen.
The light pen became moderately popular during the early 1980s. It was notable for its use in the Fairlight CMI, and the BBC Micro. However, due to the fact that the user was required to hold his or her arm in front of the screen for long periods of time, the light pen fell out of use as a general purpose input device.
Touchscreens , touch screens , touch panels or touchscreen panels are display overlays which have the ability to display and receive information on the same screen. The effect of such overlays allows a display to be used as an input device, removing the keyboard and/or the mouse as the primary input device for interacting with the eTGHALLEM
4

A graphics tablet is a computer input device that allows one to hand-draw images and graphics, similar to the way one draws images with a pencil and paper.
Graphics tablets consist of a flat surface upon which the user may "draw" an image using an attached stylus, a penlike drawing apparatus. The image generally does not appear on the tablet itself but, rather, is displayed on the computer monitor. It is interesting to note that the stylus, as a technology, was originally designed as a part of the electronics, but later it simply took on the role of providing a smooth, but accurate "point" that would not damage the tablet surface while "drawing".
Graphics tablets should not be confused with the tablet PC.
In computing, a scanner is a device that analyzes an image (such as a photograph, printed text, or handwriting) or an object (such as an ornament) and converts it to a digital image. Most scanners today are variations of the desktop (or flatbed) scanner The flatbed scanner is the most common in offices. Handheld scanners, where the device is moved by hand, were briefly popular but are now not used due to the difficulty of obtaining a high-quality image. Both these types of scanners use charge-coupled device (CCD) or
Contact Image Sensor (CIS) as the image sensor, whereas older drum scanners use a photomultiplier tube as the image sensor. eTGHALLEM
5

A digital camera is an electronic device used to capture and store photographs electronically instead of using photographic film like conventional cameras.
Modern compact digital cameras are typically multifunctional, with some devices capable of recording sound and/or video as well as photographs.
Professional digital cameras are generally dedicated to photography. In the Western market, both types of digital cameras now outsell their 35 mm film counterparts.
A barcode reader (or barcode scanner ) is a computer peripheral for reading barcodes printed on various surfaces.
Like a flatbed scanner, it generally consists of a light source, a lens and a photo conductor translating optical impulses into electrical ones. Additionally, nearly all barcode readers currently produced contain decoder circuitry analyzing the barcode's image data provided by the photo conductor and sending the barcode's content to the scanner's output port. eTGHALLEM
6

Optical mark recognition is the process of capturing data by contrasting reflectivity at predetermined positions on a page. By shining a beam of light onto the document the scanner is able to detect a marked area because it is more reflective than an unmarked surface.
Some OMR devices use forms which are preprinted onto
'Transoptic' paper and measure the amount of light which passes through the paper, thus a mark on either side of the paper will reduce the amount of light passing through the paper.
It is generally distinguished from optical character recognition by the fact that a recognition engine is not required. That is, the marks are constructed in such a way that there is little chance of not reading the marks correctly. This requires the image to have high contrast and an easily-recognizable or irrelevant shape.
One of the most familiar applications of optical mark recognition is the use of #2 (HB in
Europe) pencil bubble optical answer sheets in multiple choice question examinations.
Students mark their answers, or other information, by darkening circles marked on a preprinted sheet. Afterwards the sheet is automatically graded by a scanning machine. Most people know this by the eponym Scantron after the company that is best known for this.
In most European countries, a horizontal or vertical 'tick' in a rectangular 'lozenge' is the most commonly used type of OMR form, the most familiar application being the UK
National lottery form. eTGHALLEM
7

Magnetic Ink Character Recognition or MICR is a character recognition technology adopted mainly by the banking industry to facilitate the processing of checks. The process was demonstrated to the American Bankers Association in
July 1956, and it was almost universally employed by 1963.
Almost all US and UK checks now include MICR characters at the bottom of the paper in a font known as E-13B. The major fonts used around the world are E-13B and CMC-7.
In addition to their unique fonts, MICR characters are printed with a magnetic ink or toner. Magnetic printing is used so that the characters can be reliably read into a system, even when they have been overprinted with other marks such as cancellation stamps.
The characters are read with a device similar in nature to the head of an audio tape recorder, and the letterforms' bulbous shapes insure that each letter produces a unique waveform for the read head.
MICR numerals and control characters
Optical character recognition , usually abbreviated to OCR , is computer software eTGHALLEM of proven techniques.
8

Optical character recognition (using optical techniques such as mirrors and lenses) and digital character recognition (using scanners and computer algorithms) were originally considered separate fields. Because very few applications survive that use true optical techniques, the optical character recognition term has now been broadened to cover digital character recognition as well.
Early systems required "training" (essentially, the provision of known samples of each character) to read a specific font. Currently, though, "intelligent" systems that can recognize most fonts with a high degree of accuracy are now common. Some systems are even capable of reproducing formatted output that closely approximates the original scanned page including images, columns and other non-textual components.
Handwriting recognition is the ability of a computer to receive intelligible handwritten input. The image of the written text may be sensed "off line" from a piece of paper by optical scanning (optical character recognition).
Alternatively, the movements of the pen tip may be sensed "on line", for example by a pen-based computer screen surface. characters and finds the most plausible words.
9

Pen Computing is the effective use of pen as pointing devices to substitute conventional pointing devices such as the mouse and trackball. An example of pen computing is the
Light Pen. The Light pen is a computer input device in the form of a light-sensitive wand used in conjunction with the computer's CRT monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy. A light pen can work with any CRTbased monitor, but not with LCD screens, projectors or other display devices.
A Braille terminal is a computer input device that follows the Braille system of writing for the blind. can raise or lower a combination of six roundtipped pins. Other variants exist that use a conventional QWERTY keyboard for input and
Braille pins for output, as well as input-only and output-only devices.
10

In many contexts also known as 'automatic speech recognition', computer speech recognition or erroneously as Voice Recognition is the process of converting a speech signal to a sequence of words, by means of an algorithm implemented as a computer program. Speech recognition applications that have emerged over the last years include voice dialing (e.g., Call home), call routing (e.g., I would like to make a collect call), simple data entry (e.g., entering a credit card number), and preparation of structured documents
(e.g., a radiology report).
Voice Verification or speaker recognition is a related process that attempts to identify the person speaking, as opposed to what is being said.
Eye sensor reader is a device capable of reading data through the retina of the eye. A typical example for the use of this device is in for security purposes.
In fact like fingertips, the retina can be used to make a particular employee uniquely identifiable. eTGHALLEM
11