b. Com. Iiinformation Technology 2

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INFORMATION TECHNOLOGY

INTRODUCTION:

The use of Information Technology (IT) is well recognized. This has

become must for the survival of business houses with the growinginformation technology trends. Computer is one of the major components of

an information technology network and gaining increasing popularity.

Today, computer technology has performed every sphere of existence of

modern man. From railway reservation to medical diagnosis, from T.V programs to satellite launching, from matchmaking to criminal catching,

everywhere we witness the elegance, notification and efficiency possible only

with the help of computers.

COMPUTER: Computer is defined in the OXFORD dictionary as An automatic

electronic apparatus for making calculation or controlling operations that are

expressible in numerical or logical terms

Definition:It is an electronic device which is used to perform arithmetic and

logical operations. The word computer comes from word compute which

means to calculate.

The important confluence of the definition is the fact that the computer

can perform only those operations/calculations which can be expressed inLogical or Numerical terms. The basic function performed by a computer is

the execution of the program. A program consists if a number of sequence of

steps. Each of these steps, require air thematic or logical or input/output

operations to be performed on data. The unit which interprets a code to

generate respective control signal is termed as Control Unit (CU). The

arithmetic Logic Unit ALU) and the Control Unit (CU0 together are termedas the Central Processing Unit (CPU). The CPU is the most important

component of a computers hardware. The ALU performs the air thematicoperations such as addition, subtraction, multiplication and division.

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CHARACTERISTICS

SPEED: - A computer is a very fast device. It can perform in few secondsthe amount of work that a human being can do in many years.

ACCURACY: - The accuracy of a computer is very high nearly 100%.

Errors can occur but these are mainly due to human rather than technologicalweakness.

DELIGENCE: -Unlike human beings, a computer is free from monotonytiredness, lack of concentration and hence can work for hours together.

VERSALITY: - A computer is capable of performing almost any taskprovided that the task can be reduced to a series of logical steps.

POWER OF REMEMBERING: -In computer every piece of informationcan be retained as long as desired by the user and can be recalled as andwhen required.

NO INTELLIGENCE QUOTIENT AND NO FEELING: -Computers donot have their own I.Q and own feeling.

CLASSIFICATION OF COMPUTERS

Present day computers can be classified into three categories.

1. ANALOG COMPUTERS: -These are computers which work on thebasis of continuous measurements of physical quantities e.g. pressure

voltage current length temperature etc. Example- Thermometer,

speedometer, wall-clock.

2. DIGITAL COMPUTERS :- This are the computers which show thedata in terms of the discrete numbers and processes data using the

standard arithmetic operations These computers directly operate on

numbers and produce precise results.

3. HYBRID COMPUTERS: - These computers have the qualities ofboth analog and digital computers.

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CLASSIFICATION OF DIGITAL

COMPUTERS

1. MICRO COMPUTERS: - It is the low cost small digital computer.This type of computer contains a microprocessor at its CPU a memory

unit, input and output devices. The word length of these computers lies between 8 to 32 bits. These have a wide range of applications e.g.

Personal computers, desktop micro computers, portable micro

computers.

2. MINICOMPUTERS: - These are more faster than micro computers.The word length of these computers is usually 32-bits. A mini computer

can support up to 64 or even 100 terminals. They are extensively used

for multi user and interactive applications in colleges universities,research organizations, industries and so on.

3. MAIN FRAME COMPUTERS:- The mainframe remains a distinctclass of computers and are very powerful large general purpose

computers. Large organizations use mainframe computers. Speed ofthese computers is million of instructions per second.(MIPS)

4. SUPER COMPUTER: - These computers are much faster and more

powerful than mainframe computers. Super computers are speciallydesigned to maximize the number of flops. These computers are

operational, mostly at research centers and government agencies with

scientific or engineering functions are used. E.g. Deep blue computer,

Param computer.

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PRIMARY

MEMORY

PROCESS

MEMORY

SECONDARY

MEMORY

PRIMARY

MEMORY

INPUT

OUT PUT


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STORAGE DEVICES

The same device can be used to overwrite the earlier data and

store some new data just as in an audio cassette. The devices used

are:-

1. MAGNETIC TAPE: - It is a plastic tape which is half inchwide and 600, 1200 or 2400 feet in length. One side of the plastic tape

is coated with iron oxide which is used for the recording of data. The

tape is divided into tracks frames across its length.

2. MAGNETIC DISC: - The magnetic tape has a seriouslimitation in that it is sequently device. The disk allows us to have a

direct access just as in a gramophone record.

(1)Floppy Disk or Micro Disk

(2)Hard Disk

FLOPPY DISK: - There are two types of floppies commonlyused i.e. (a) 3/1/2 inch diskettes (b) 5/1/4 inch diskettes.

(a) 3/1/2 inch diskettes:-

This is an enclosed in a rigid protective cover. Inside the cover,

the micro disks the same familiar flexible plastic with iron oxide

coating. There is a read write opening which is sealed by a sliding

mental protector.

(b) 5/1/4 inch diskettes:-

This dish has a whole in the middle where the disk drive holds it.

The disk has a square jacket around it. This is protected by a tape.

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Those devices which receive results and other information from computer

and provides it to the user are known as output devices.

PRINTER(A)DOT MATRIX PRINTER

(B)INKJET PRINTER

(C)LASER PRINTER

(D)DAISY WHEEL PRINTER

MONITOR(A)MONOCHROME (BLACK AND WHITE)

(B)CGA (COLOR GRAPHIC ADAPTOR)(C)EGA (ENHANCED GRAPHIC ADAPTOR)

(D)VGA (VIDEO GRAPHIC ADAPTOR)

(E)SVGA(SUPER VISUAL GRAPHIC ADAPTOR)

PLOTTER

(A) DROM PRINTER

(B)MICRO GRIP PRINTER

(C)FLAT BED PRINTER

(D) INK-JET PRINTER

(E)FLAT BED TYPE

(F)ROLER FEED TYPE

PRINTERPrinters are output devices that print the result of an operation on paper.

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MECHANISM

NON IMPACT PRINTERSIMPACT PRINTERS


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A printer is capable of producing output that contains printed words. It is

also capable or printing straight lines and simple figures like squares

rectangles and circles .Printer are classified based on a number of

parameters; like the mechanism used for printing; the speed of printing

the quality of output the direction of printing and the kind of interface

they have with the computer .the following section will elaborate onthese parameters

SPEED

QUALITY OF OUTPUT

DIRECTION

INTERFACE

PLOTTERS

It is used to create high-quality visuals on paper which cannot be obtained

using a printer .for this purpose ;a plotter is used .plotter is an output device

that is used to create presentation visuals ;charts ;graphs tables and diagrams

A plotter consists of an arm that moves across the paper on which thediagram or graph needs to be drawn A pen moves along the arm ;and the arm

itself moves relative to the paper A combination of the to thus providesmovement along the horizontal and vertical axes.

In some plotter the paper is held stationary while the arm and the

pen move over it. This is called a flat-bed plotter .In the other type of

plotter ;the paper is wrapped around a drum and anchored at both ends .the

drum rotates while the pen moves laterally along a fixed rail thus is called a

drum plotter

SPEAKER (SOUND OUTPUT)Music can be made by some special programs to activate the loudspeaker

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DEVICES WHICH ARE USED TO FEED DATA AND INSTRUCTIONS TO THE COMPUTER ARE CALLED INPUT

DEVICES

IMPORTANT IMPUT DEVICES ARE :

o KEYBOARD

o MOUSE

o TRACKBALL

o GAME DEVICES

o PEN INPUT

o TOUCH SCREEN

o GLIDE PAD

o SOUND INPUT DEVICES

o VOICE INPUT DEVICES

o VIDEO INPUT DEVICES

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MOUSE

A mouse is an input device that is used to point and select an option on the

VDU. A mouse can be classified on the basis of the number of buttons it has,the technology it uses and the kind of interface it has with the computer. A

mouse may have one, two or all three of them. In its simplest form, a mousehas one button. Moving the mouse on a flat surface produces a corresponding

movement of a pointer on the screen. Placing the pointer on an option and

clicking the button results in selecting that option. A mouse may be classified

as a mechanical mouse or an optical mouse, on the basis of technology used.

In a mechanical mouse, the ball that projects through the bottom surface

rotates as

The mouse is moved along a flat surface. The direction of rotation is

detected and relayed to the computer by the switches inside the mouse.

Microsoft, IBM and Logitech are some well known makers of the mechanical

mouse. An optical mouse uses a light beam instead of a rotating ball to detect

the movement across a specially patterned mouse pad. MSC Corporation

makes the optical mouse that uses LEDs and photo detectors to trap

movement.

SCANNERSAnother input device that is being increasingly used is the scanner. Often, there are

situations when some information (picture or text) is available on paper and is

needed on the computer disk for further editing. The simplest way would be to take

a photograph of the image directly from the source, and convert it into a form that

can be saved on the disk and then printed. A scanner scans an image and

transforms the image to ASCII codes that is the code used by a computer to

represent the characters you find on your keyboard- letters of the alphabet,

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numbers punctuation marks and graphics. These can be edited, manipulated and

printed. Scanners are of two types- the flat-bed type and the roller-feed type.

While in the roller feed type scanner, the image is passed over a roller where it is

captured, the flat bed scanner works like a photocopier. Flat-bed scanners can scan

and store images from books without having to remove the page, which is difficult

in the case of the roller-feed scanner.

Many of the scanners available now-a-days are capable of

not only scanning text and graphic files. Scanners are used to reproduce

photographs on the computer screen. They can be employed in training programs

using the computer and in desktop publishing. Business use scanners for storing

documents on the computer.

TOUCH SCREENS

Touch screens are normally used when information has to be accessed with

minimum effort. Two popular technologies exist for touch screens. In one, the

screen is made sensitive to touch and the exact position is detected. In the, other

the screen is lined with the light emitting devices and photo detectors. When the

users finger approaches the screen, the light beam is broken and is detected by the

photo detectors.

Touch screens are used in information-providing systems like the explained above.

It is also used in airline and railway reservation counters. The users indicate their

current location and the destination by touching the screen, and all the possible

routes with timings and rates are displayed.

LIGHT PENS

A light pen is a pointing device that can be used to select an option

at it; or drawing figures directly on the screen .Alight pen has a photo detector

can detect Changes in brightness of the screen. When the pen is pointed at aparticular spot on the screen; it records change in brightness instantly and informs

the computer about this .The computer can find out the exact spot with this

information .thus the computer can identify where you are pointing on the screen

KEY BOARD

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The keyboard is one of the most common input devices for computer.

It is used for entering information and instructions into the computer. Most of the

keyboards have 101 keys.

Meaning of WWW

www stands for world wide web. The World Wide Web is officially

described as wide area hypermedia information retrieval initiative aiming to

give universal access to a long universal of documents.

Search Engine

A search maintains a database of Keywords. When you request the search

engine for the information. It attempts to locate the specified information inthe database of keywords. If the search engine finds a match, it displayed its

references. Examples of popular search engines are yahoo, WebCrawler,

AltaVista, excite, info seek and Lycos.

Make Your E-Mail Address

Step-1: Connect Computer to the Internet and Open a site for Exp:

hotmail.com

Step-2: Click a sign up for a free mail account link from the mail hotmailhome page. You will get a form. Fill this form on computer itself.

Step-3: A Copy of the form is given.

Step-4: You will get a few terms of services being provided by hotmail.com

at the end of the hotmail terms of the services you will get two options. I

dont accept. Just click at I Accept.

Step-5: After the form is completely filled. Please, click at Sign up Key.

You have got your e-mail address ready which will be as follows:

Your login name (a) hotmail.com you will always have to

remember your password, which is the key to open your e-mail box.

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www. @yahoo.com

WEBSITES VISITED

1. www.ddnow.com

2. www.jnu.inc.com

3. www.mdu.inc.com

4. www.gju.inc.com5. www.ignou.org

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http://www.jnu.inc.com/http://www.mdu.inc.com/http://www.gju.inc.com/http://www.ignou.org/http://www.jnu.inc.com/http://www.mdu.inc.com/http://www.gju.inc.com/http://www.ignou.org/

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