INPUT DEVICE

“The device that is used for giving input to the system is called “Input Device”. Input devices are used not only for entering data but also for giving instructions to computer about what to do.

EXAMPLE

Some common input devices are keyboard, mouse, joystick, optical character reader, light pen, scanner, disk drive etc.

KEYBOARD

“A keyboard is a device that converts letters, numbers and other characters into electrical signals that are machine readable by the computer processor”.

A keyboard is connected with the system unit through a dedicated keyboard port. As soon as a key is pressed for a character a signal for that character is generated that passes directly to the main storage of the computer.

DIVISIONS OF KEYBOARD

A keyboard can be dived into four general areas:

_ Alphanumeric Keyboard

_ Numeric Keyboard

_ Function Keyboard

_ Screen Navigation & Editing Keys

ALPHANUMERIC KEYBOARD

The position of various keys in the alphanumeric keypad is similarto those on a typical typewrite and is also called typewriter’s area. Alphanumeric keypad consists of:

Alphabet keypad consists of keys A to Z having upper case and lower case letter.

Number Keys consist of keys from 0 to 9.

Punctuation Keys, special characters keys and space bar for punctuation marks, special characters such as + * & ^ etc.

NUMERIC KEYPAD

A numeric keypad is a set of keys at the right of the keyboard similar to those on a calculator. This keypad performs two actions.When num lock is on, these keys are used for rapid entry of numeric data and when num lock is off, these keys are used for cursor control.

FUNCTIONKEYS

There are 12 function keys labeled as F1……….. F12. They are located on the left or on top of the keyboard. There are used to instruct the computer to perform certain commands. In different software’s function keys combine with CTRL, ALT & SHIFT to perform handy shortcuts.E.g. ALT + F4 (Close Application), CRTL + F3 (Choose Print Preview) etc.

SCREEN NAVIGATION AND EDITING KEYS

Four cursor control keys are used to move the cursor on the screen in the direction shown by the arrows on these keys.

EXAMPLES

Backspace: Moves cursor one place to the left, deleting the character.

Enter : Moves cursor to next line.

Delete : Delete character on right hand side.

Page Up : Used to move the cursor to the previous page

Page Down : Used to move the cursor to the next page

MOUSE

A mouse is a useful input device. It is a pointing device used to select various options. A mouse is a small unit with two or three buttons. When moved over a surface or pad, it moves a small object(often an arrow, called mouse cursor) across the screen. A mouse is used to draw things on screen and to select objects. It is really easyto use as compared to keyboard.

JOYSTICK

It is an input device. It is attached to the computer using a cable connected to a “Game Port”. Joystick is mostly used for playing games as it provides an easy environment for game playing. A joystick can be used by manipulating the handle of joystick to position the cursor and click on a button. It is the most popular input device for playing video games and is extremely popular in young kids. Joystick is only used for gaming entertainment and not for business purposes.

SCANNER

A scanner is an input device which translates the images and photos into digital data that can be stored by a computer.

The scanner converts every bit of the scanned material into electrical pulses.

With the use of OCR (Optical Character Recognition) software, it is even possible to convert a scanned document into text that can later onbe edited.

To edit photographs, graphics application (like Adobe Photoshop, the Gimp) are required.

Scanners come in a variety of forms such as full-size flatbed scanners, hand help scanners, drum scanners, overhead/film scanners etc.

TRACK BALL

A trackball is a pointing device almost like a mouse.

The user controls the cursor on the screen by rolling a plastic ball with a fingertip. To execute the command with a trackball, one or more buttons are pressed, much in the same way as is done with a mouse. The cursor can be moved around on the screen by rolling the ball with a thumb or finger.

Trackball is popular among users fo laptop computers when space is limited and may e mounted on either side of the keyboard.

ELECTRIC LIGHT PEN

A light pen is a pen like input device attached to some video display terminal. In specially designed display screen, data can be entered with a light pen or existing data can be modified.

The user brings the pen to a desired point on the display screen and presses the button, which identifies the screen location to thecomputer.

MICROPHONES & VOICE/SPEECH RECOGNITION

The speech recognition device accepts the spoken commands and converts them into digital code, which can be processed by the computer.

VOICE/SPEECH RECOGNITION

The capability of translating voice into text is known as “Voice/Speech Recognition”.

DIGITAL CAMERA

The digital camera uses a CCD (Charged Coupled Device) which is usedfor storing the image unlike an ordinary camera which uses a film for capturing images.

Images taken by a digital camera are directly accessed by computer.