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Computer Input Devices

An input device is used to feed data into a computer. Input devices are capable of converting data into a form which can be recognized by computer. A computer can have several input devices. Namely Keyboard, Mouse, Joystick, OCR, MICR etc.

1.    Keyboard:
The most common input device is the keyboard. Keyboard consists of a set of   typewriter like keys that enable you to enter data into a computer. They are:
 Alphabetic Keys: To enter letters,
 Numeric keys: To enter numbers,
 Punctuation Keys: To enter comma, period, and semicolon etc.,
 Functional Keys: To perform some specific functions.
The keyboard detects the key pressed and generates the corresponding ASCII codes which can be recognized by the computer.

Types of keyboards:
a)    Standard Keyboards have their basic layout. The average number of keys on a regular keyboard is 105/108, though range of 95-108 light variations, especially in the manner the keys are placed. QWERTY keyboards are the most common and have the six alphabets Q. W, E. R, T, and Y in the first row .
b)    Ergonomics refers to the study of methods that can reduce stress on muscles to avoid repetitive strain injury. It mostly deals with optimizing posture and technique while working, so the work can be carried out in the easiest manner with the least possible strain on any muscle joint or organ. Ergonomic keyboards are designed in such a way that typing can be done putting the least amount of stress on the fingers and wrist. This is a radical type of keyboard designed to prevent Carpal Tunnel Syndrome.
c)     Wireless Keyboard is a keyboard that does not need to be connected to the computer via a wire. This makes it very convenient for the user to use the keyboard comfortably. Wireless keyboard use Bluetooth, Infrared (IR), and Radio Frequencies to connect to the computer with the help of batteries and transmitted and receiver with the range 1 to 40 feet distance contact between the computer and the keyboard type very ineffective.
d)    Virtual keyboard are software devices that let you input data just like a hardware keyboard. They open up as an application and can be controlled by a mouse or via a touch screen. They are mainly used in device which  do not necessarily require a keyboard, like a tablet or a smart-phone .They are useful as they aid in making the size of the device smaller. Virtual keyboards are also used in situation concerning security, as anything enter on an ordinary keyboard is recorded in a key log, leading to security risks associated with passwords or PIN numbers. This is the reason many banks provide the facility of a virtual keyboard in their online banking operations.
e)     Compact keyboard are slim and usually do not have the numeric keypad that is present on the right side of other keyboards. These are typically used in laptop, where sizing issue makes it difficult to accommodate a standard keyboard. To make up for the small size, these keyboards rely on the use of multiple keys to carry out functions that would only use a single key on  a standard- sized keyboard. Some models also include a touch-pad that can be used instead of the mouse. These are not extremely small in size, but offer portability during travel and storage. Another benefit of compact keyboards is that they can be used by people with certain disabilities that hinder them from effectively using hand and finger movements
2.     Mouse:
Mouse is an input device that controls the movement of the cursor on the display screen. The display screen is map in the form of graphical points dot is called pixel. The number of pixels differs depending upon the resolution of the screen. Mouse is a small device; you can roll/navigate along a flat surface.
 In mouse, a small ball/IR ray is kept inside that touches' the pad through a hole at the bottom of the mouse. When the mouse is moved, the ball rolls/position on the screen, this movement of the ball/position is converted into signals and sent to the computer. You will need to click the button at the top of the mouse to select the option. Mouse pad is a pad over which you can move a mouse. Mouse is very popular in modern computers. There are basically three types of mice.
      I.          Mechanical: This mouse has a small hard rubber ball underneath that moves against two roller as it passes across a flat surface. Mechanical sensors detect the movement of the rollers as an ‘x’ and ‘y’ axis and accordingly cursor will move.
   II.          Optomechanical: This mouse works on the same principle. The rollers have wheels, as the wheels spin, a light sensitive optical device counts the number of holes that pass by and convert those numbers to an ‘x’ and ‘y’ axis.
III.          Optical: This mouse more accurate or precise and has no moving parts. It uses a laser to detect movement on optical reference grid.
3.    Joystick:
Joystick is an input device consisting of a stick that pivot on a base and report its angle or direction to the device it is controlling.
Joy ticks are often used to control video games; simulated programs usually have one or more push-buttons whose state can also be read by the computer. A popular variation of the joystick is used on modern video game consoles is the analogy stick.
4.     OMR,OCR & MICR
Optical reading of the pictures, symbols and, shapes are scanned with the help of laser beam, usually the position is pre-programmed accessed and documented instantly.
 I ) Optical Mark Reader And Recognition(OMR)
Special pre-printed forms are designed with boxes which can be marked with a dark pencil or ink. Such documents are read by a reader, which transcribes the marks into electrical pulses which are transmitted to the computer. They are widely used in applications like objective type answer papers evaluation in which large number of candidates appear, time sheets of factory employees etc.
II) Optical Character Recognition(OCR)
The OCR technique permits the direct reading of any printed character without any special ink. With OCR, a user can scan a page from a book. The computer will recognize the characters in the page as letters and punctuation marks, and stores. This can be edited using a word processor the size (width,height and depth) of the scanned.
III) Magnetic Ink Character Recognition (MICR)
 MICR is widely used by banks to process cheques. Human readable numbers are printed on documents such as cheque using a special magnetic ink. The cheque can be read using a special input unit, which can recognize magnetic ink character . This method eliminate the manual errors. It also save time, ensures security and accuracy of data.

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