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DEVICEBASEDCONTROLS

• Input Devices: Through which people
communicate to system.

✓TRACKBALL
✓JOYSTICK
✓GRAPHICS TABLET
✓LIGHT PEN
✓VOICE
✓MOUSE
✓KEYBOARD

TYPESOFDEVICECONTROLL

• Operated on the screen itself-DIRECT DEVICES
E.g. : light pen, touch screen

• Other than the screen :INDIRECTDEVICES
• E.g. : Mouse, Keyboard

USEOFDEVICEBASEDCONTROL

• Topoint an object on the screen
• Toselect anobject
• To drag
• Totrack or follow a moving object
• Toposition anobject
• Toenter or manipulate information

TRACKBALL

• Aspherical object (ball) that rotates freely
• Direction and speed is translated in to cursor

movement
• Well suited for video games or 3D

Environments



CONTD..

• ADVANTAGES

➢Direct relationship between hand and pointer in
terms of direction andspeed

➢Does not require additional desk space

• DISADVANTAGES

➢ 5 finger movement is needed
➢ indirect control
➢ difficult to control
➢ requires a degree of eye hand coordination

JOYSTICK

CONTD..

• Stick /bat shaped device in variablesizes
• It responds by exerting pressure onthem
• Some permits continuous movement, some

others support vertical & horizontal
movement
• Direct relation between pointer and handin
terms of direction.
• Indirect relation between hand and pointer in
terms of speed and distance

GRAPHIC TABLET

• Sensitive horizontal surfaces .
• We can operated with fingers ,light pen,

object like stylus
• Requires additional desk space
• Direct relationship in terms of speed,distance

and direction

TOUCH SCREEN..

• Screen which is sensitive to finger or stylus
• Direct relationship in terms of speed,distance

and direction

• Does not require additional desk space

• May damage the screen

LIGHT PEN

• Screen can be controlled by a pen or stylus
• Direct relationship in terms of speed,distance

and direction
• More accurate than finger touching.

VOICE

• Automatic speech recognition by the
computer

• Useful when people do not usekeyboard
• Simple and direct
• Difficult to use in noisyenvironment
• High error rates



MOUSE

• Arectangular or dome shaped movable device
containing one to three buttons used to
manipulate objects on the screen

• Direct relationship in terms of speed ,distance
and direction

• Requires additional desk space



KEYBOARD

• Standard typewriter keyboard and cursor
movement keys

• No direct relation ship between finger
movement on the keyboard and cursor
movement on the screen

• Keyboard accelerators: way to accessmenu
elements without displaying amenu



How to select one??

• Factors

▪ Task
▪ User
▪ Environment
▪ Hardware
▪ The device in relation to application
▪ Minimizing eye and hand movements