Input Device

The device through which can supply any form textual, audible, visual, graphic or mechanical data or

instruction into the computer system or the channel through which computer receives the data is called input device. The most popular input devices are as follows:

1 Keyboard:

The most popular main computer input device that contain a series of switches each of which generates a series of different pulse codes so that the computer knows the one that was pressed. The most common input device which is used both for text based data input or instruction into the computer. The keys are arranged in a similar way to a typewriter. Keyboards usually have the following:

• Keys for the letters of the alphabet from a-z and A-Z.
• Keys for punctuation symbols like !, @, #, %, etc. (Exclamation, at the rate, Hash, percentage etc).
• Numbered keys or a numeric keypad (or both) from 0-9.
• Keys to move the typing cursor and other text controls, such as Tab, Insert, Delete, Backspace, Enter and so on.
• Enter: - It is the most important key on the keyboard; it is used to change the paragraph. It is also used to enter into the selected computer program by pressing it once.
• Backspace: - It is used to delete one character to the let of cursor.
• Delete: - It is used to delete one character to the right of cursor. It is also used to delete computer item.
• Shift: - It is used to capitalize the letter.
• ESC: - It is used to close the dialog boxes and also to terminate the running process.
• ALT: - It is used to activate the menu bar and close the current windows with the help some other
• keys.
• CTRL: - Mainly it is used for short keys to perform specific task inside the computer programs.
• Windows key: - It is used to activate the START BUTTON.
• Keys which change the function of other keys, such as Shift, Caps Lock, Alt, and Ctrl.
• Function keys numbered from F1 to F12.

Types of keyboard (Based on model):

QWERTY - 

The most popular is the standard QWERTY keyboard. The newer keyboards can have a

trackball built into the keyboard. This allows the user the convenience of a built in pointing device.

• 83-key PC and XT keyboard
• 84-key AT keyboard
• 101-key enhanced keyboard
• 104 keys or 108 keys are also available for Windows and Internet.

Ergonomic - 

This keyboard is built son that the keyboard is divided into two parts. One half fits the right hand and the other half fits the left hand. This split keyboard arrangement is built to fit the natural positioning of the hand and to help with repetitive motion hand injury which occurs when a job is carried out over and over again.

2.Mouse

The mouse is an input device .It is small box with a round ball on the bottom, and more than one buttons on the top. It is hold in one hand and moved across a flat surface. A standard mouse uses a ball inside the housing at the bottom to represent movement. The mouse can be used to select text or command and manipulate data on the screen by clicking the buttons. Generally a mouse contains at least on to as many three buttons. Different buttons have different function depending on the running

program. 

                 The mouse is also useful for graphic programs that allow you to draw picture by using the

mouse like a pen, pencil or paintbrush.

a)Mechanical mouse                 b) Opto-mechanical mouse                       c) Optical mouse

a) Mechanical mouse: -

A mechanical mouse works by mechanical action of its different parts. It has a rubber or metal ball on its underside that can roll in all directions. When this mouse is rolled across a flat surface, different rollers inside the mouse move and generate electric signals. These signals are given to the computer and computer converts them into proper action on the screen.

b) Opto-Mechanical mouse: - 

The basic construction of the opto-mechanical mouse is same as that of the mechanical mouse. Only difference in the sensing circuit used to detect the movement of the mouse.

c) Optical Mouse: - 

Optical mouse used a laser to detect the mouse movement. They respond move quickly, but they are also more expensive.

Mouse can be divided into following categories

1) Serial mouse :- it has 9 pin and D type in shape.

2) Bus mouse: - It has 6 pin and circular type in shape.

3) USB mouse: - USB stands for Universal Serial Bus, USB mouse connects to USB port.

4) Wireless mouse: - in this type of mouse, everything is similar-p:t}_ to the conventional (not natural) mouse except that no cable is used to connect the mouse to the computer system.

Basically there are two types of wireless mouse

a) Infrared Wireless mouse

b) Radio-controlled wireless mouse.

C.) SCANNER

A scanner is an input device that helps to transfer printed text, handwriting and graphic (image) into

the computer.

                               “OR”

A scanner is an input device that scans images, printed text, hand writing and converts in to a digital

image and then sends to the computer. Scanners are used for quick input of text or images. It is very easy input method.

                          To connect a scanner to the computer, you would need an additional card in the board, which usually comes with the scanner. Now days, scanner comes with USB model, so you needn’t insert additional card for scanner.

D.) Web cam

Web cam is like a video camera on home computer that allow the user to see people of the same time they communicate on internet. It can also be used to create a movie, take digital photographs, internet chatting, video phone and messenger programs such as yahoo Messenger, Windows Live messenger and Skype. It is specially used in bank, hotel, hospital, departmental stores, and different organizations for the security control. It is also called PC cameras.

E) Light pen

Light pen is also a very useful input device. It is a light sensitive pointing device. Which looks like a pen? It allows the user to point the displayed objects or draw directly on the computer screen. It can work with any CRT (Cathode Ray Tube) screen, but it can’t work with LCD screens. The pen operates on two cell batteries span of 8 month if used for 30 minutes daily. It is used in engineering drawing, architect design, circuit design and other several graphics and art works.

F) Digital Camera

A digital camera is a camera that takes video or photographs or both , digitally and inputs to the computer in the digital format. At first, the photographs are stored in the camera’s memory and then transferred to a computer through a cable. Then we can edit that photograph according to our requirement. Most of the camera we use today are digital.

G) Touch Screen

It is a kind of screen that consists of touch sensitive display panel covering the screen. We can use our

fingers to select object and give command to the computer like a mouse. It replaces the use of mouse or light pen. We can use our finger to points the object on the screen.

H) Microphone

A microphone also called a mike is an input device that converts sound into an electrical signal. Microphones are used in many applications such as telephone, tape recorders, live and recorded audio in radio and television and in computers for recording voice etc.

I) Joysticks

Many games require a joystick for the proper playing of the game. A joystick consists of a base and a stick perpendicular to the base. The stick can be moved in any direction, enabling the user to move and object around the computer screen. A joystick can perform a similar function to a mouse or trackball, but is only commonly used for playing games.