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What is Input and Output devices

What is the difference between an input and output device?



An input device sends information to a computer system for processing, and an output device reproduces or displays the results of that processing. Depending on the interaction, a device can be both, referred to as an input/output or I/O device.


Examples

An input device can send data to another device, but it cannot receive data from another device. Examples of an input device include a computer keyboard and mouse, which can send data (input) to the computer, but they cannot receive or reproduce information (output) from the computer.




An output device can receive data from another device, but it cannot send data to another device. Examples of an output device include a computer monitor, projector, and speakers, which can receive data (output) from the computer, but they cannot send information (input) to the computer. An input/output device can send data to another device and also receive data from another device. Examples of an input/output include a computer CD-RW drive and USB flash drive, which can send data (input) to a computer and also receive data (output) from a computer.




Keyboard


The keyboard is one of the common input device of computer.It is a typewriter like device which is used to type in the letters, digits and commands. The layout of the keyboard is like that of the QWERTY typewriter, although there are some extra command and function keys provided therein. Basically a keyboard contains a matrix of switches (one switch per key):Each key, when pressed,sends a digital code to the computer that determines which key has been pressed e.g.,if you press 'A' when caps lock button is On, a code of 01000001 is sent to computer; computer then translates this code to determine that you pressed 'A' from the keyboard. Substantial development has taken place in the ergonomics of keyboard design to ensure that operator strain is minimal.





Keyboard interfaces

Today, most desktop computer keyboards connect to the computer using either USB or Bluetooth for wireless communication. Before USB, a computer may have used PS/2 or AT (Din5) as a keyboard interface.





     Advantages

  • Relible way of inputing text and Number.
  • Available in variery of formats.

     Disadvantages

  • Not useful for entering some spcific type of data (e.g. pictures,diagrams, voice, video etc.)
  • Very slow while accessing menu options or selecting various objects on screen.
  • Very slow while moving windows or other objects.
  • Not much useful for enlarging or changing sizes of windows on screen.



Pointing device

A pointing device is an input interface (specifically a human interface device) that allows a user to input spatial (i.e., continuous and multi-dimensional) data to a computer. ... Movements of the pointing device are echoed on the screen by movements of the pointer (or cursor) and other visual changes.





An input device used to move the pointer (cursor) on screen. The major pointing device is the mouse for the desktop computer and the touchpad for the laptop, although many road warriors bring along a mouse. Pointing sticks are available on some laptops, and a small number of users prefer trackballs over the mouse. See mouse, touchpad, trackball and pointing stick.


     Mouse

A computer mouse is an input device that is most often used with a personal computer. Moving a mouse along a flat surface can move the on-screen cursor to different items on the screen. Items can be moved or selected by pressing the mouse buttons (called clicking).[1] It is called a computer mouse because of the wire that connects the mouse to the computer. The people who designed the first computer mice thought that it looked like the tail on a mouse. Today, many computer mice use wireless technology and have no wire.

     Advantages

  • Ideal for pointing objects/options on desktop computers.
  • Most familliar and easily to use pointing device.

     Disdvantages

  • Need a flat surface close to computer.
  • A mouse can not easily be used with a laptop or a notebook or a palm top computrs.

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