Computer Input Device Information

list of computer input devices 

1) Keyboard

With a keyboard, a person can type a document, use keystroke shortcuts, access menus,
play games and perform a variety of other tasks. Though keyboards can have different
keys depending on the manufacturer, the operating system that they are designed for, and
whether they are attached to a desktop computer or are part of a laptop most keyboards
have between 80 and 110 keys, including
• Typing keys (letters A to Z, a to z, characters like < , ? + = etc.)
• A numeric keypad (numbers 0 to 9, characters like ! @ # ( ) etc.)
• Function keys (F1 to F12)
• Control keys (Ctrl, Alt, Del, Pg Up, Pg Dn, Home, End, Esc, , Fn, arrow keys.)
Function keys allow users to enter frequently-used operations with a single keystroke
and Control keys allow cursor and screen control. Displayed objects and menus can be
selected using the Control keys.A keyboard is a lot like a miniature computer. It has its own processor, circuitry (keymatrix) and a ROM storing the character map. It uses a variety of switch technology.Though the basic working technology is same there are design variations to make the
keyboards easier and safer to use, versatile and elegant. Some of the non-traditional keyboards
are Das keyboard, Virtual Laser keyboard, True-touch Roll-up keyboard, Ion Illuminated
keyboard, and Wireless keyboard.


2) Mouse

A mouse is 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. It has become an
inseparable part of a computer system just like the keyboard. A cursor in the shape of an
arrow or cross-hair always associated with a mouse. We reach out for the mouse whenever
we want to move the cursor or activate something or drag and drop or resize some object
on display. Drawing or designing figures and shapes using graphic application packages
like AutoCAD, Photoshop, CorelDraw, and Paint is almost impossible without mouse.
The mouse’s 2D motion typically translates into the motion of a pointer on a display. In
a mechanical mouse a ball – roller assembly is used; one roller used for detecting X direction
motion and the other for detecting Y direction motion. An optical mouse uses LED and
photodiodes (or optoelectronic sensors) to detect the movement of the underlying surface,
rather than moving some of its parts as in a mechanical mouse. Modern Laser mouse uses
a small laser instead of a LED.
 A mouse may have one, two or three buttons on the top. Usually clicking the primary or
leftmost button will select items or pick screen-points, and clicking the secondary or rightmost
button will bring up a menu of alternative actions applicable to the selected item or specific
to the context. Extra buttons or features are included in the mouse to add more control or
dimensional inputs.


3) Joystick

A joystick is used as a personal computer peripheral or general control device consisting of
a hand-held stick that pivots about the base and steers the screen cursor around. Most
joysticks are two-dimensional, having two axes of movement (similar to a mouse), but
three-dimensional joysticks do exist. A joystick is generally configured so that moving the
stick left or right signals movement along the X-axis, and moving it forward (up) or back
(down) signals movement along the Y-axis. In joysticks that are configured for three-dimensional movement, twisting the stick left (counter-clockwise) or right (clockwise)
signals movement along the Z-axis. In conventional joystick potentiometers, or variable
resistors, are used to dynamically detect the location of the stick and springs are there to
return the stick to centre position as it is released.

Joysticks are often used to control games, and usually have one or more push-buttons
whose state can also be read by the computer. Most I/O interface cards for PCs have a
joystick (game control) port. Joysticks were popular during the mid-1990s for playing
games and flight-simulators, although their use has declined with promotion of the mouse
and keyboard.

Input Device / Fundamentals Of Computer


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