Input: Pointing Devices

Input: Keyboard

The most often used input device is the keyboard.

The layout of the keys was borrowed from the typewriter with a number of new keys added. Various keyboards have different extra keys. A keyboard for a Windows computer has different extra keys than one for an Apple computer. Laptop computers have fewer keys but have an additional Fn key, that can be combined with other keys to replace the missing keys. Keyboards can be customized for other languages, too.

Example: Windows Keyboard

Click on a key above (or section of keys) and see an explanation below.

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Explanation:

A variety of pointing devices are used to move the cursor on the screen.

The most commonly used ones have two or three buttons to click for special functions.

Mouse

Old type: A ball underneath rolls as the mouse moves across the mouse pad. New type: A laser shines on the surface under the mouse to detect the motion of the mouse. High tech! No mouse pad is needed if the surface is smooth but has variation in color or texture. The cursor on the screen follows the motion of the mouse. Buttons on the mouse can be clicked or double-clicked to perform tasks, like to select an icon on the screen or to open the selected document. Many recent mice have a scroll wheel as the middle button. Wireless mice are very popular. No cord to deal with - just batteries. Practice clicking on the images of mice above. The image will change with a successful click.

Advantage:	Moves cursor around the screen faster than using keystrokes.
Disadvantage:	Requires moving hand from keyboard to mouse and back. Repeated motion is tiring and can lead to carpal tunnel syndrome

Trackball

Instead of moving the whole mouse around, the user rolls the trackball only, which is on the top or side.

Advantage:	Does not need as much desk space as a mouse. Less strain since less motion is needed.
Disadvantage:	Requires fine control of the ball with just one finger or thumb. Repeated motions of the same muscles is tiring and can cause carpal tunnel syndrome.

Glidepad, Touchpad

Copyright (c) 123RF Stock Photos Uses a touch sensitive pad for controlling cursor. The user slides finger across the pad and the cursor follows the finger movement. For clicking there are buttons, or you can tap on the pad with a finger. The glidepad is a popular alternate pointing device for laptops.

Advantage:	Does not need as much desk space as a mouse since it does not move. Can readily be built into the keyboard. Has finer resolution. That is, to achieve the same cursor movement onscreen takes less movement of the finger on the glidepad than it does movement of the mouse. Can use either buttons or taps of the pad for clicking.
Disadvantage:	The hand tires faster than with a mouse since there is no wrist or hand support. Some people don't find the motion as natural as a mouse.

Game Devices

Cursor position is controlled by a joystick or with arrow buttons.

Advantage:	A joystick gives a more natural-feeling control for motion in games, especially those where you are flying a plane or spaceship. Both have more buttons for special functions than a mouse and can combine buttons for even more actions.
Disadvantage:	More expensive Bulky Better ones require an additional peripheral card for best performance

Pen Input

Used esp. in Personal Digital Assistants (PDA) and some tablets and smart phones. The pen is also called a stylus. Pen Input is used for:

Data Input-	By writing. Optical Character Recognition reads your handwriting and turns it into text. (If only your friends could read your handwriting, too!) By drawing. Graphics tablets create a picture with your pen strokes.
Pointing Device-	Functions like a mouse in moving a cursor around the screen and clicking by tapping the screen.
Command Gestures -	You can issue commands by moving pen in patterns. So a certain kind of swirl would mean to save the file and a different kind of swirl could mean to open a new file.

Advantage:	Can use handwriting instead of typing. Better for taking notes. Can use gestures instead of typing commands. Faster. Small size of device. Easier to draw with a stylus than with a mouse.
Disadvantage:	May have to train device to recognize handwriting. Must learn gestures or train device to recognize the ones you create Can lose the pen, which is not usually attached to the device

Touchscreen

Make selection by just touching the screen. Used on smart phones, tablets, and screens in some larger devices like ATMs and gas pumps.

Advantage:	It's natural to do - reach out and touch something.
Disadvantage:	It's tiring if many choices must be made. It takes a lot of screen space for each choice since fingers are bigger than cursors.

Дата добавления: 2014-12-23