input device of computer

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Introduction to Information Technology, 2nd EditionTurban, Rainer & Potter

2003 John Wiley & Sons, Inc.

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INPUT DEVICESINPUT DEVICES Devices which are used for entering the data

into the computer.

The process of entering the data into thecomputer system.

Transferring the data into the Machine readable

form.

Supply the data for further processing.


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Data Entry Concepts

Entering of the data into the computer intimely manner, at reasonable cost and withminimum of errors.

2 basic ways in which data are entered:1. Transcriptive Data Entry

2. Source Data Entry

In Transcriptive, the data is entered ondocuments. For example, handwritten.

In Source Data Entry, the data are preparedat source in machine-readable form.


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ON-LINE/OFF-LINE

Device used to enter the data can be either

on-line or off-line.

On-line refers to devices that are directly

connected to CPU.

Off-line refers to devices that are not directly

connected.


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INPUT ACCURACY

Errors may occur during entering the data.

2 various methods used to eliminate the

errors:1. Verification

2. Validation

Verification is the checking of data against

a known source.

Validation is the checking of data that

deviate from this range.


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INPUT DEVICES

Input is the process of entering andtranslating incoming data into Machine-readable form.

Hardware is the physical component ofcomputer system.

Any hardware that is attached to main unitof computer is Peripheral Device.

So input device is peripheral device throughwhich data is entered.

Various Input Devices are.


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1. KEYBOARD

Most preferred and common input device.

Traditional QWERTY keyboard.

Feature of the Keyboard:1. Standard Typewriter Keys

2. Function Keys

3. Special Purpose keys

4. Cursor-movement keys

5. Numeric keys


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2. MOUSE

Developed by Doug Engelbart in 1960.

It is used instead of Enter (Return) key on

keyboard.

Operates either electromechanically or

optically.

electromechanical mouse has sphere on its

under side. Optical mouse travels over special table of grid

lines.


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3. JOYSTICK

Input device that enables the user to control the

position of the cursor with the help of lever.

It sends the digital signals to control the cursor

movements. Used to play computer games.

It provides the user eight direction movements.


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Introduction to Information Technology, 2nd

EditionTurban, Rainer & Potter


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4.TRACKBALL

Input device which is variation in the mouse.

It is like an upside down mouse.

It has ball on the top and the user moves the

ball directly with the hands.

Firstly used in the Laptops.

Rotation of the sphere translates the direction

and speed into digital signals used to controlthe cursor.


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5.TOUCHPAD

Input device used in the modern laptops.

User can move the cursor around the screen

by moving the finger on the pad.

For clicking there are two buttons and also

the user can tap the pad for clicking an icon.


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6.TRACKPOINT

Input button which is protruded in between

the keys of the keyboard.

Works like mouse.

Rotate the cursor around the screen.


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8.

LIGHTPENHand held pen shaped input device connected

by cable to computer and is used special software

to detect light.

It looks like an ordinary pen but its tip is light

sensitive detector.

It does not emit light rather it reacts to light

through photosensitive detector. Frequently used by the graphic designers and

drafting engineers.


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9.

Digitizer Input device similar to light pen.

Difference is it uses separate pad called

graphic tablet on which the pointing deviceis moved.


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11. MICR

Magnetic-ink Character Recognition.

The interpretation by computer of line of

characters written in special magnetic ink. Mainly used in the banks for the

processing of cheques.


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12.OMR

Optical-Mark Recognition.

Simplest form of optical recognition.

Employs mark sensing. High intensity of light that is directed in

the form of beam at the sheets of the

paper being fed through it. To scan and translate the locations of pen

or pencil marks into computer.


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13. BCR (OBR)

Bar Coded Recognition (Optical Bar

Recognition).

Optical bar reader scans, recognizes andinterprets a patterns of lines that form a

bar code.

Bar code also called product codes.

By passing some laser beams.

UPC (Universal Product Code)


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14.OCR

Optical Character Recognition.

Device that reads alphanumeric

characters of both handwritten or typedtext.

These characters are interpreted by

passing some strong light.

The characters must be recognized by

standardized fonts called Optical fonts.

input device of computer

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