"POINTING DEVICES"

 Pointing Device

A pointer represents a small symbol on the screen. It usually appears on the screen in graphical users Interface (GUI) environment.Appointing device is an input device. It is used to control the movement f cursor or pointer on the screen. It can also be used for;

§  Sending commands signal to the computer

§  Selecting items on the screen

§  Selecting commands from the command menu.

§  Drawing graphs etc.

    Name of some pointing device

    The name of some most important importing devices are follows.

§             Mouse

§           Trackballs

§           Pointing stick

§           Joy stick

§          Touch pad

§        Touch screen

§        Light pen

§        Digitizing/ graphical designing

Q.4   Describe the function of following devices.

 

(i)                  Mouse

(ii)                Trackballs

(iii)               Touch pad

 

(i)                  Mouse

A mouse is a pointing input device. It looks like a mouse. It is most commonly used in Windows Environment on the personal computers. It is used to control the cursor or pointer on the screen and to give commands to the computer. It is very easy to use. The commands can be given to the computer very easy and quickly. The mouse is attached with a computer by a cable or wireless connection.

  A mouse (mechanical mouse) has a small ball at its bottom. the ball rotates as the mouse is rolled over a flat surface. normally, ad (also known as mouse pad) is used as flat surface. As the mouse is rolled over the flat surface, the pointer moves on the screen. The mouse also has two or three buttons on the top. Usually, mouse is used to select any icon, or option by pointing the mouse pointer on it and clicking one of the buttons of the mouse to perform an action.

 Today, optical mouse is used with some PCs. It has no ball its bottom. It uses the laser technology to detect the mouse movements.

 

(ii)            Trackball

A trackball is also a pointing device. It performs function like a, mouse but it is a stationary device. It has a movable ball on its top. The ball is rotated or rolled with fingers (or palm of the hand) to control the movement of pointer on the screen; like a mouse, a trackball, also has buttons to send the command to the computer. However, a trackball has additional bottom=ns whose functions vary depends upon the software.

The trackball is usually available with laptop computers. It is fixed on its keyboard. The laptop computers are used by the travelling users. The trackball fulfills the need of those users that have no flat surface to roll the traditional mouse.

 

(iii)          Touch pad

Touch pad is a pressure-sensitive pointing input device. Touch pad is also known as trackpad. It is also a stationary device like a trackball but it has no moving parts. It is a small, flat surface over which we slide our finger tip to move the pointer on the screen for pointing a desired icon. As we slide our fingertip on the flat surface of touchpad, the pointer or cursor moves in the screen. Some touch pads have one or more buttons. These are close to the pad. These buttons work like a mouse buttons. Touch pads are commonly used with the portable computers (laptops) and are built-in on their keyboard.

 

 

Q.5 write a note on;

 

(i)                  Pointing stick

(ii)                Joy stick

 

(i)               Pointing stick

A pointing stick is a pressure -sensitive pointing device. It looks like a pencil eraser. It exists between G, H and B keys of keyboard. It is also used to control movement of a pointer on the screen. The pointer on the screen moves in a direction in which the pointing stick is pushed. There are also two or more buttons under the speaker key of the keyboard. A command or a potion on the screen selected by pointing the pointer on it and pressing one of the buttons with thumb pointing stick input device is normally use with laptop computers.

 

 

 

(ii)            Joy stick

Joy stick is also a pointing device. It consists of a vertical handle like a gearshift lever mounted on a base and with one or two buttons. The vertical handle (or handled stick) is used to control the movement on the screen. The button of the stick is pressed to activate certain event or action. the joy stick is basically used to paly games. It is also in some computer-aided design (CAD) systems.

 

Q.6   Describe the functions of touch screen and light pen.

 

(i)               Touch Screen

 

A touch screen is a special video display screen. Input is given to the computer directly by touching the screen with user fingertip. Most touch screen computer use sensors in the computer’s screen to detect the touch of a finger. Usually touch screen is used to make selection from a menu of choice displayed on the screen. Touch screen is often used in ATMs. Touch screen is also used in restaurants, supermarkets, departmental stores.

 

In some computer systems, pen-based or light-pen input device are used. The user touches the screen by a pen. However, the term touch screen implies a system that accepts a input data by touching the screen with the user’s fingertip.   

 

(ii)            Light pen

                                        

                                                The light pen is a handheld pointing input device. It is a light-sensitive stylus, or pen- like device. It is connected by a computer by a wire. Light pen has a photocell mounted at its front end. When the front end of the pen is touched with the monitor screen, the photocell detects or senses a position on display screen. This device also has a button. The user point s the object to be selected on the display scree and presses a button a light pen. Light pen device is used by engineers, graphic designers, and illustrator. This device requires special monitors. Light pen is used in personal User Assistant (PDA) and other types of handheld computers.

 

Q.7       What are the pen-based systems?

 

             Pen-Based systems

 

            Pen-based systems uses a pen-like input device such as stylus. This system allows a user to enter handwriting and marks into a computer. The user writes information on the display screen with end-like input device instead of typing on the keyboard. This system used special software. This software translates handwriting information or marks into a form that can be stored and processed by a computer.

           The handled computer such as PDA (personal digital Assistant) is an example of pen-based system. The primary input device of a PDA is the stylus. a stylus is an electronic pen. It looks like a smallball point pen this input device is used to enter information into the PDA but writing on the screen. It can also use as pointing device for select command.

 

Q.8      What is digitizer or graphic tablet. Also describe the function of stylus and pack input device.

 

Digitizer or Graphic tablet

 

A digitizer is also known as graphic tablet. It is a flat, rectangular, electronic board (or pad). Each location on a digitizer point to corresponding position on the computer screen, it is mainly used for making maps and engineering drawings. The input device or pack (or cursor) is used to trace drawing and sketches on the digitizer.

When you draw on digitizer with the help of stylus or cursor, it converts the movement of stylus or cursor into digital signals that are sent into the computer. Thus, digitizer makes it easy to enter free-hand drawing into the computer.