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COMPUTER FUNDAMENTALS

Unit–I: Computers

Introduction - Definition - History of Computers - Characteristics -Generation of Computers -

Capabilities and Limitations - Operating System- Need of Operating system- Concept of BIOS -

Booting Files - Basic Components of a Computer System-Control Unit- ALU- Input/output functions

and characteristics. Memory-Classifications - Volatile Memory and Non- Volatile - Flash Memory,

ROM, RAM, EPROM, PROM, EEPROM and other types of Memory.

Unit–II: I/O Devices

Input/output and Storage Units- Keyboard - Pointing Devices: Mouse, Trackball, Touch Panel, Light

Pen, Scanners -Types of Monitors - Touch-sensitive screens - Optical Recognition System - Pen

based systems – Digitizers - MICR – OCR- OMR - Bar-code Reader-Hard Copy Devices:- Impact

and Non- Impact Printers- Daisy Wheel - Line Printer - Chain Printer - Comb Printers- Non Impact

Printers – DeskJet- Laser Printer- Thermal Transfer Printer- Barcode Printers - Electro static printers

and plotters.

Unit–III : Languages

High Level Language and Low Level Language- Software - Types - Hardware- Firmware – Compiler

- Interpreter and Assembler. File Allocation Table (FAT, FAT 32 and NTFS)- Introduction to

algorithm and Flow chart - Algorithm development -Flowchart -Symbols- Pseudo code-Editors-

Formatted and Unformatted- Memory Systems- RAM ROM, Hard disk - Introduction to Extra

Peripherals - Scanner, CD/DVD - Working With Backup Devices-External Storage devices.

Unit–IV: Ms-Office

Introduction – Menus - Tools – Tool bar. Ms Word: Preparing documents and formatting - Macros -

Ms Excel: Introduction Menus and Tools - Function and Chart -Ms Power Point: Introduction - Menus

and Tools- Preparing Presentations.

Unit–V : Internet

Introduction to Network – Types - Concepts of World Wide Web - Understanding web Features-

usage World Wide Web - WWW Technologies - Creating e-mail id – Sending and Receiving mail –

Chatting – Types – Blog - Forum- Rss- feedback.

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Unit–I

Computers Introduction

Let us begin with the word ‘compute’. It means ‘to calculate’. We all are familiar with

calculations in our day to day life. We apply mathematical operations like addition,

subtraction, multiplication, etc. and many other formulae for calculations. Simpler

calculations take less time. But complex calculations take much longer time. Another

factor is accuracy in calculations. So man explored with the idea to develop a machine

which can perform this type of arithmetic calculation faster and with full accuracy. This

gave birth to a device or machine called ‘computer’.

The computer we see today is quite different from the one made in the beginning. The

number of applications of a computer has increased, the speed and accuracy of

calculation has increased. You must appreciate the impact of computers in our day to

day life. Reservation of tickets in Air Lines and Railways, payment of telephone and

electricity bills, deposits and withdrawals of money from banks, business data

processing, medical diagnosis, weather forecasting, etc. are some of the areas where

computer has become extremely useful.

However, there is one limitation of the computer. Human beings do calculations on their

own. But computer is a dumb machine and it has to be given proper instructions to carry

out its calculation. This is why we should know how a computer works.

Definition

Computer is an electronic device. As mentioned in the introduction it can do arithmetic

calculations faster. But as you will see later it does much more than that. It can be

compared to a magic box, which serves different purpose to different people. For a

common man computer is simply a calculator, which works automatic and quite fast. For

a person who knows much about it, computer is a machine capable of solving problems

and manipulating data. It accepts data, processes the data by doing some mathematical

and logical operations and gives us the desired output.

Therefore, we may define computer as a device that transforms data. Data can be

anything like marks obtained by you in various subjects. It can also be name, age, sex,

weight, height, etc. of all the students in your class or income, savings, investments,

etc., of a country. Computer can be defined in terms of its functions. It can i) accept data

ii) store data, iii) process data as desired, and iv) retrieve the stored data as and when

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required and v) print the result in desired format. You will know more about these

functions as you go through the later lessons.

A computer has four functions:

a. accepts data Input

b. processes data Processing

c. produces output Output

d. stores results Storage

Input (Data):

Input is the raw information entered into a computer from the input devices. It is the

collection of letters, numbers, images etc.

Process:

Process is the operation of data as per given instruction. It is totally internal process of

the computer system.

1.3.3 Output:

Output is the processed data given by computer after data processing. Output is also

called as Result. We can save these results in the storage devices for the future use.

HISTORY OF COMPUTER:

History of computer could be traced back to the effort of man to count large numbers.

This process of counting of large numbers generated various systems of numeration

like Babylonian system of numeration, Greek system of numeration, Roman system of

numeration and Indian system of numeration. Out of these the Indian system of

numeration has been accepted universally. It is the basis of modern decimal system of

numeration (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). Later you will know how the computer solves all

calculations based on decimal system. But you will be surprised to know that the

computer does not understand the decimal system and uses binary system of

numeration for processing.

We will briefly discuss some of the path-breaking inventions in the field of computing

devices.

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Calculating Machines:

It took over generations for early man to build mechanical devices for counting large

numbers. The first calculating device called ABACUS was developed by the Egyptian

and Chinese people.

The word ABACUS means calculating board. It consisted of sticks in horizontal

positions on which were inserted sets of pebbles. A modern form of ABACUS is given in

Fig. 1.2. It has a number of horizontal bars each having ten beads. Horizontal bars

represent units, tens, hundreds, etc.

Napier’s bones

English mathematician John Napier built a mechanical device for the purpose of

multiplication in 1617 A D. The device was known as Napier’s bones.

Slide Rule

English mathematician Edmund Gunter developed the slide rule. This machine could

perform operations like addition, subtraction, multiplication, and division. It was widely

used in Europe in 16th century.

Pascal's Adding and Subtractory Machine

You might have heard the name of Blaise Pascal. He developed a machine at the age

of 19 that could add and subtract. The machine consisted of wheels, gears and

cylinders.

Leibniz’s Multiplication and Dividing Machine

The German philosopher and mathematician Gottfried Leibniz built around 1673 a

mechanical device that could both multiply and divide.

Babbage’s Analytical Engine

It was in the year 1823 that a famous English man Charles Babbage built a mechanical

machine to do complex mathematical calculations. It was called difference engine. Later

he developed a general-purpose calculating machine called analytical engine. You

should know that Charles Babbage is called the father of computer.

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Mechanical and Electrical Calculator

In the beginning of 19th century the mechanical calculator was developed to perform all

sorts of mathematical calculations. Up to the 1960s it was widely used. Later the

rotating part of mechanical calculator was replaced by electric motor. So it was called

the electrical calculator.

Modern Electronic Calculator

The electronic calculator used in 1960 s was run with electron tubes, which was quite

bulky. Later it was replaced with transistors and as a result the size of calculators

became too small.

The modern electronic calculator can compute all kinds of mathematical computations

and mathematical functions. It can also be used to store some data permanently. Some

calculators have in-built programs to perform some complicated calculations.

CHARACTERISTICS OF COMPUTER

Let us identify the major characteristics of computer. These can be discussed under the

headings of speed, accuracy, diligence, versatility and memory.

Speed

As you know computer can work very fast. It takes only few seconds for calculations

that we take hours to complete. Suppose you are asked to calculate the average

monthly income of one thousand persons in your neighborhood. For this you have to

add income from all sources for all persons on a day to day basis and find out the

average for each one of them. How long will it take for you to do this? One day, two

days or one week? Do you know your small computer can finish this work in few

seconds? The weather forecasting that you see every day on TV is the results of

compilation and analysis of huge amount of data on temperature, humidity, pressure,

etc. of various places on computers. It takes few minutes for the computer to process

this huge amount of data and give the resul

You will be surprised to know that computer can perform millions (1,000,000) of

instructions and even more per second. Therefore, we determine the speed of computer

in terms of microsecond (10-6 part of a second) or nano-second (10-9 part of a second).

From this you can imagine how fast your computer performs work.

Accuracy

Suppose someone calculates faster but commits a lot of errors in computing. Such

result is useless. There is another aspect. Suppose you want to divide 15 by 7. You

may work out up to 2 decimal places and say the dividend is 2.14. I may calculate up to

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4 decimal places and say that the result is 2.1428. Someone else may go up to 9

decimal places and say the result is 2.142857143. Hence, in addition to speed, the

computer should have accuracy or correctness in computing.

The degree of accuracy of computer is very high and every calculation is performed with

the same accuracy. The accuracy level is determined on the basis of design of

computer. The errors in computer are due to human and inaccurate data.

Diligence

A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for

hours without creating any error. If millions of calculations are to be performed, a

computer will perform every calculation with the same accuracy. Due to this capability it

overpowers human being in routine type of work.

Versatility

It means the capacity to perform completely different type of work. You may use your

computer to prepare payroll slips. Next moment you may use it for inventory

management or to prepare electric bills.

Power of Remembering

Computer has the power of storing any amount of information or data. Any information

can be stored and recalled as long as you require it, for any numbers of years. It

depends entirely upon you how much data you want to store in a computer and when to

lose or retrieve these data.

No IQ

Computer is a dumb machine and it cannot do any work without instruction from the

user. It performs the instructions at tremendous speed and with accuracy. It is you to

decide what you want to do and in what sequence. So a computer cannot take its own

decision as you can.

No Feeling

It does not have feelings or emotion, taste, knowledge and experience. Thus it does not

get tired even after long hours of work. It does not distinguish between users.

Storage

The Computer has an in-built memory where it can store a large amount of data. You

can also store data in secondary storage devices such as floppies, which can be kept

outside your computer and can be carried to other computers.

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COMPUTER GENERATIONS

You know that the evolution of computer started from 16th century and resulted in the

form that we see today. The present day computer, however, has also undergone rapid

change during the last fifty years. This period, during which the evolution of computer

took place, can be divided into five distinct phases known as Generations of Computers.

Each phase is distinguished from others on the basis of the type of switching circuits

used.

First Generation Computers

First generation computers used Thermion valves. These computers were large in size

and writing programs on them was difficult. Some of the computers of this generation

were:

ENIAC: It was the first electronic computer built in 1946 at University of

Pennsylvania, USA by John Eckert and John Mauchy. It was named Electronic

Numerical Integrator and Calculator (ENIAC). The ENIAC was 30 50 feet long, weighed

30 tons, contained 18,000 vacuum tubes, 70,000 registers, 10,000 capacitors and

required 150,000 watts of electricity. Today your favorite computer is many times as

powerful as ENIAC, still size is very small.

EDVAC: It stands for Electronic Discrete Variable Automatic Computer and was

developed in 1950. The concept of storing data and instructions inside the computer

was introduced here. This allowed much faster operation since the computer had rapid

access to both data and instructions. The other advantage of storing instruction was that

computer could do logical decision internally.

Other Important Computers of First Generation

EDSAC: It stands for Electronic Delay Storage Automatic Computer and was

developed by M.V. Wilkes at Cambridge University in 1949.

UNIVAC-1: Ecker and Mauchly produced it in 1951 by Universal Accounting

Computer setup.

Limitations of First Generation Computer

Followings are the major drawbacks of First generation computers.

1. The operating speed was quite slow.

2. Power consumption was very high.

3. It required large space for installation.

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4. The programming capability was quite low.

Second Generation Computers

Around 1955 a device called Transistor replaced the bulky electric tubes in the first

generation computer. Transistors are smaller than electric tubes and have higher

operating speed. They have no filament and require no heating. Manufacturing cost was

also very low. Thus the size of the computer got reduced considerably.

It is in the second generation that the concept of Central Processing Unit (CPU),

memory, programming language and input and output units were developed. The

programming languages such as COBOL, FORTRAN were developed during this

period. Some of the computers of the Second Generation were

1.IBM 1620: Its size was smaller as compared to First Generation computers and

mostly used for scientific purpose.

2.IBM 1401: Its size was small to medium and used for business applications.

3.CDC 3600: Its size was large and is used for scientific purposes.

Third Generation Computers

The third generation computers were introduced in 1964. They used Integrated Circuits

(ICs). These ICs are popularly known as Chips. A single IC has many transistors,

registers and capacitors built on a single thin slice of silicon. So it is quite obvious that

the size of the computer got further reduced. Some of the computers developed during

this period were IBM-360, ICL-1900, IBM-370, and VAX-750. Higher level language

such as BASIC (Beginners All purpose Symbolic Instruction Code) was developed

during this period.

Computers of this generation were small in size, low cost, large memory and

processing speed is very high.

Fourth Generation Computers

The present day computers that you see today are the fourth generation computers that

started around 1975. It uses large scale Integrated Circuits (LSIC) built on a single

silicon chip called microprocessors. Due to the development of microprocessor it is

possible to place computer’s central processing unit (CPU) on single chip. These

computers are called microcomputers. Later very large scale Integrated Circuits

(VLSIC) replaced LSICs.

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Thus the computer which was occupying a very large room in earlier days can now be

placed on a table. The personal computer (PC) that you see in your school is a Fourth

Generation Computer.

Fifth Generation Computer

The computers of 1990s are said to be Fifth Generation computers. The speed is

extremely high in fifth generation computer. Apart from this it can perform parallel

processing. The concept of Artificial intelligence has been introduced to allow the

computer to take its own decision. It is still in a developmental stage.

OPERATING SYSTEM

Set of computer programs that manage and control hardware resources and provide an

interface between the user and computer. Examples: DOS, OS2, WINDOWS, UNIX,

Macintosh and Linux operating system.

Technical and widely used terms

CHIP : Is an integrated circuit – a thin wafer of silicon that contains miniaturized

circuitry. TRANSISTOR: a device that controls flow of current through its resistor. It

controls flow of electrons through a circuit. Transistors are miniature electronic devices

inside a chip. Intel Pentium III chip contains 28 millions of transistors. The size of

today’s transistors is about 180 nanometers.

MODEM: A peripheral device that converts the digital signals used inside the

computer to an analog or voice signal that can be transmitted over the phone lines.

ANALOG: A device that operates on continuously varying data.

GEOGRAPHIC INFORMATION SYSTEM (GIS): a set of complex computer

programs that utilizes hardware and software resources in a computer to manipulate,

process, and analyze spatial data. It also provides a graphical interface for presenting

spatial data. Examples: Arc/Info, ArcView, INTEGRAPH, SPANS, IDRISI, GRASS,

ArcGIS etc.

Booting

The process of loading the system files of the operating system from the disk into the

computer memory to complete the circuitry requirement of the computer system is

called booting. The system files of MS. DOS are:

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Types of Booting

There are two types of booting:

• Cold Booting: If the computer is in off state and we boot the computer by

pressing the power switch ‘ON’ from the CPU box then it is called as cold booting.

• Warm Booting: If the computer is already ‘ON’ and we restart it by pressing the

‘RESET’ button from the CPU box or CTRL, ALT and DEL key simultaneously from the

keyboard then it is called warm booting.

MEMORY

Memory is one of the most important elements of every computer. The computer

memory is electronic circuitry that holds data and program instructions until it is their

turn to be processed. There are three types of computer memory: RAM, CMOS, and

ROM.

RAM

Random Access Memory: It is a temporary holding area for data before and after they

are processed. It is like scratch paper – volatile (after the computer is turned off all data

is gone). It consists of thousands of circuits that each hold one bit of data. The computer

holds (stores) data in RAM and copies it to the CPU and from the CPU (processor) back

to RAM. RAM is a holder of data and also instructions. When the processor turns into a

“word processor” the instructions for this activity are copied from the disk to RAM. 32

MB RAM means that the RAM can hold 32 million bytes of data.

CMOS

Complementary Metal Oxide Semiconductor: This is a battery-powered chip that

retains data about the computer configuration when the computer is turned off.

Read Only Memory (ROM):

There is another memory in computer, which is called Read Only Memory (ROM). Again

it is the ICs inside the PC that form the ROM. The storage of program and data in the

ROM is permanent. The ROM stores some standard processing programs supplied by

the manufacturers to operate the personal computer. The ROM can only be read by the

CPU but it cannot be changed. The basic input/output program is stored in the ROM

that examines and initializes various equipment attached to the PC when the switch is

made ON. The memories, which do not lose their content on failure of power supply, are

known as non-volatile memories. ROM is non-volatile memory.

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PROM

There is another type of primary memory in computer, which is called Programmable

Read Only Memory (PROM). You know that it is not possible to modify or erase

programs stored in ROM, but it is possible for you to store your program in PROM chip.

Once the programmers are written it cannot be changed and remain intact even if power

is switched off. Therefore programs or instructions written in PROM or ROM cannot be

erased or changed.

EPROM:

This stands for Erasable Programmable Read Only Memory, which over come the

problem of PROM & ROM. EPROM chip can be programmed time and again by erasing

the information stored earlier in it. Information stored in EPROM exposing the chip for

some time ultraviolet light and it erases chip is reprogrammed using a special

programming facility. When the EPROM is in use information can only be read.

Cache Memory:

The speed of CPU is extremely high compared to the access time of main memory.

Therefore the performance of CPU decreases due to the slow speed of main memory.

To decrease the mismatch in operating speed, a small memory chip is attached

between CPU and Main memory whose access time is very close to the processing

speed of CPU. It is called CACHE memory. CACHE memories are accessed much

faster than conventional RAM. It is used to store programs or data currently being

executed or temporary data frequently used by the CPU. So each memory makes main

memory to be faster and larger than it really is. It is also very expensive to have bigger

size of cache memory and its size is normally kept small.

Registers:

The CPU processes data and instructions with high speed, there is also movement of

data between various units of computer. It is necessary to transfer the processed data

with high speed. So the computer uses a number of special memory units called

registers. They are not part of the main memory but they store data or information

temporarily and pass it on as directed by the control unit.

Memory types:

Volatile and non-volatile memory

Volatile memory is memory that loses its contents when the computer or hardware

device loses power. Computer RAM is a good example of a volatile memory. Non-

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volatile memory, sometimes abbreviated as NVRAM, is memory that keeps its contents

even if the power is lost. CMOS is a good example of a non-volatile memory.

BIOS Basic Input/output System.

A very nuts-and-bolts set of programs that control hardware (called “drivers”). There are

two BIOSs: one found in ROM and one that is found in the operating system. As drivers

improve, it’s impossible to change everybody’s computer ROM. So, the operating

system BIOS simply does the work for the ROM BIOS.

Driver

A special program that controls a computer component.

Operating System

A critical program that interfaces all hardware with the user’s programs.

All computers have an operating system of some kind.

Program

A set of instructions to accomplish a specific task.

In order for the computer to function correctly, it has to “talk” to all the components you

have attached. Most of the time, you may not even be aware of all that goes on

between accepting a keystroke from the keyboard and a letter appearing on the display.

To us it makes perfect sense that a letter “a” from the keyboard will show as letter “a” on

the screen.

Everything in the computer is controlled by some “program”. One crucial program is the

“Operating system”. Looking at the name, you can think of it as a program that is

composed of a “system” of controls which “operate” on the hardware. This is true: there,

are several individual controls that manipulate the display, keyboard, hard disk, floppy

drive, etc. Without these controls, you would not be able to do anything with the

computer.

There are several intrinsic controls that help the computer “come-alive” (or “boot-

up”).These controls are found in the computer’s BIOS (Basic Input/output System). The

BIOS actually is in ROM (part of the computer’s persistent memory) and describes to

the computer how to interact with the display, keyboard, hard disk, floppy, clock, parallel

port and serial port.

You will note that I did not mention CD-ROM and scanner. This is where device drivers

come in. Device drivers are special control programs that help the operating system

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know how to work with “exotic” devices or work with particular devices better. The

support programs for PC hardware came out earlier than CD-ROM and scanner

technology. Drivers not only improve device control but also add support for new

standards. If you do not have a device driver for some component, you will not be able

to work with it.

Computer capabilities and limitations

Like all machines, a computer needs to be directed and controlled in order to perform a

task successfully. Until such time as a program is prepared and stored in the

computer’s memory, the computer ‘knows’ absolutely nothing, not even how to accept

or reject data. Even the most sophisticated computer, no matter how capable it is, must

be told what to do. Until the capabilities and the limitations of a computer are

recognized, its usefulness cannot be thoroughly understood.

In the first place, it should be recognized that computers are capable of doing repetitive

operations. A computer can perform similar operations thousands of times, without

becoming bored, tired, or even careless.

Secondly, computers can process information at extremely rapid rates. For example,

modern computers can solve certain classes of arithmetic problems millions of times

faster than a skilled mathematician. Speeds for performing decision-making operations

are comparable to those for arithmetic operations but input-output operations, however,

involve mechanical motion and hence require more time. On a typical computer

system, cards are read at an average speed of 1000 cards per minute and as many as

1000 lines can be printed at the same rate.

Thirdly, computers may be programmed to calculate answers to whatever level of

accuracy is specified by the programmer. In spite of newspaper headlines such as

‘Computer Fails’, these machines are very accurate and reliable especially when the

number of operations they can perform every second is considered. Because they are

man-made machines, they sometimes malfunction or break down and have to be

repaired. However, in most instances when the computer fails, it is due to human error

and is not the fault of the computer at all.

In the fourth place, general-purpose computers can be programmed to solve various

types of problems because of their flexibility. One of the most important reasons why

computers are so widely use today is that almost every big problem can be solved by

solving a number of little problems—one after another.

Finally, a computer, unlike a human being, has no intuition. A person may suddenly find

the answer to a problem without working out too many of the details, but a computer

can only proceed as it has been programmed to.

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Using the very limited capabilities possessed by all computers, the task of producing a

university payroll, for instance, can be done quite easily. The following kinds of things

need to be done for each employee on the payroll. First: Input information about the

employee such as wage rate, hours worked, tax rate, unemployment insurance, and

pension deductions. Second: Do some simple arithmetic and decision making

operations. Third: Output a few printed lines on a cheque. By repeating this process

over and over again, the payroll will eventually be completed.

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Unit–II

I/O Devices Input and Output

I/O (input/output), pronounced "eye-oh," describes any operation, program, or device that transfers data to or from a computer. Typical I/O devices are printers, hard disks, keyboards, and mouses. In fact, some devices are basically input-only devices (keyboards and mouses); others are primarily output-only devices (printers); and others provide both input and output of data (hard disks, diskettes, writable CD-ROMs).

Storage

Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data. Data storage is one of the core functions and fundamental components of computers. Storage refers to storage devices and their media not directly accessible by the CPU, (secondary or tertiary storage) — typically hard disk drives, optical disc drives, and other devices slower than RAM but more permanent. A computer system usually contains several kinds of storage, each with an individual purpose

Keyboard

A keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches. Following the decline of punch cards and paper tape, interaction via teletype-style keyboards became the main input device for computers.

Pointing device

A pointing device is an input interface (specifically a human interface device) that allows a user to input spatial (i.e., continuous and multi-dimensional) data to a computer. CAD systems and graphical user interfaces (GUI) allow the user to control and provide data to the computer using physical gestures — point, click, and drag.

Mouse

In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons. It sometimes features other elements, such as "wheels", which allow the user to perform various system-dependent operations, or extra buttons or features that can add more control or dimensional input. The mouse's motion typically translates into the motion of a cursor on a display, which allows for fine control of a graphical user interface.

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Track ball

Essentially, a trackball is a mouse lying on its back. To move the pointer, you rotate the

ball with your thumb, your fingers, or the palm of your hand. There are usually one to

three buttons next to the ball, which you use just like mouse buttons.

The advantage of trackballs over mice is that the trackball is stationary so it does not

require much space to use it. In addition, you can place a trackball on any type of

surface, including your lap. For both these reasons, trackballs are popular pointing

devices for portable computers.

Touch panel

A type of display screen that has a touch-sensitive transparent panel covering the

screen. Instead of using a pointing device such as a mouse or light pen, you can use

your finger to point directly to objects on the screen.

Although touch screens provide a natural interface for computer novices, they are

unsatisfactory for most applications because the finger is such a relatively large object.

It is impossible to point accurately to small areas of the screen. In addition, most users

find touch screens tiring to the arms after long use.

Light pen

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An input device that utilizes a light-sensitive detector to select objects on a display

screen. A light pen is similar to a mouse, except that with a light pen you can move the

pointer and select objects on the display screen by directly pointing to the objects with

the pen.

Scanners

A scanner is a device that captures images from photographic prints, posters, magazine pages, and similar sources for computer editing and display. Scanners come in hand-held, feed-in, and flatbed types and for scanning black-and-white only, or color. Very high resolution scanners are used for scanning for high-resolution printing, but lower resolution scanners are adequate for capturing images for computer display. Scanners usually come with software, such as Adobe's Photoshop product, that lets you resize and otherwise modify a captured image.

Image scanner

An image scanner—often abbreviated to just scanner— is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop (or flatbed) scanner where the document is placed on a glass window for scanning.

Hand-held scanners, where the device is moved by hand, have evolved from text scanning "wands" to 3D scanners used for industrial design, reverse engineering, test and measurement, orthotics, gaming and other applications. Mechanically driven scanners that move the document are typically used for large-format documents, where a flatbed design would be impractical.

Types of monitors

A cathode ray tube or CRT, is traditionally used in most computer monitors and the advent of plasma screens, LCD, DLP, OLED displays, and other technologies. As a result of CRT technology, computer monitors continue to be referred to as "The Tube". A CRT works by moving an electron beam back and forth across the back of the screen. Each time the beam makes a pass across the screen, it lights up phosphor dots on the inside of the glass tube, thereby illuminating the active portions of the screen. By drawing many such lines from the top to the bottom of the screen, it creates an entire screenful of images.

A Liquid crystal display (LCD) is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. It uses very small amounts of electric power, and is therefore suitable for use in battery-powered electronic devices.

A plasma display is an emissive flat panel display where light is created by phosphors excited by a plasma discharge between two flat panels of glass. The gas discharge

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contains no mercury a mixture of noble gases (neon and xenon) is used instead. This gas mixture is inert and entirely harmless.

The glass panels seem to be vacuum sealed, because when they are broken the plasma breaks up, seemingly from the addition of air to the space.

Surface-conduction electron-emitter display (SED) is a flat-panel, high-resolution display. Some SEDs have a diagonal measurement exceeding one meter (approximately 40 inches). The SED consists of an array of electron emitters and a layer of phosphor, separated by a small space from which all the air has been evacuated. Each electron emitter represents one pixel. The SED requires no electron-beam focusing, and operates at a much lower voltage than a CRT. The brightness and contrast compare favorably with high-end CRTs. Prototype electron emitters have been developed with diameters of a few nanometers. SED technology can offer unprecedented image resolution.

Digital Light Processing (DLP) is a technology used in projectors and video projectors. In DLP projectors, the image is created by microscopically small mirrors laid out in a matrix on a semiconductor chip, known as a Digital Micromirror Device (DMD). Each mirror represents one pixel in the projected image. The number of mirrors corresponds to the resolution of the projected image: 800x600, 1024x768, 1280x720, and 1920x1080 (HDTV) matrices are some common DMD sizes. These mirrors can be repositioned rapidly to reflect light either through the lens or on to a heat sink.

An organic light-emitting diode (OLED) is a thin-film light-emitting diode(LED) in which the emissive layer is an organic compound OLED technology is intended primarily as picture elements in practical display devices. These devices promise to be much less costly to fabricate than traditional LCD displays. When the emissive electroluminescent layer is polymeric, varying amounts of OLEDs can be deposited in rows and columns on a screen using simple "printing" methods to create a graphical color display, for use as computer displays, portable system screens, and in advertising and information board applications. OLED may also be used in lighting devices. OLEDs are available as distributed sources while the inorganic LEDs are point sources of light.

Optical Recognition System:

Often abbreviated OCR, optical character recognition refers to the branch of computer

science that involves reading text from paper and translating the images into a form that

the computer can manipulate (for example, into ASCII codes). An OCR system enables

you to take a book or a magazine article, feed it directly into an electronic computer file,

and then edit the file using a word processor.

All OCR systems include an optical scanner for reading text, and sophisticated software

for analyzing images. Most OCR systems use a combination of hardware (specialized

circuit boards) and software to recognize characters, although some inexpensive

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systems do it entirely through software. Advanced OCR systems can read text in large

variety of fonts, but they still have difficulty with handwritten text.

The potential of OCR systems is enormous because they enable users to harness the

power of computers to access printed documents. OCR is already being used widely in

the legal profession, where searches that once required hours or days can now be

accomplished in a few seconds.

Pen based computers:

A computer that utilizes an electronic pen (called a stylus) rather than a keyboard for

input. Pen computers generally require special operating systems that support

handwriting recognition so that users can write on the screen or on a tablet instead of

typing on a keyboard. Most pen computers are hand-held devices, which are too small

for a full-size keyboard.

Ditgitizer:

To translate into a digital form. For example, optical scanners digitize images by

translating them into bit maps. It is also possible to digitize sound, video, and any type

of movement. In all these cases, digitization is performed by sampling at discrete

intervals. To digitize sound, for example, a device measures a sound wave's amplitude

many times per second. These numeric values can then be recorded digitally.

MICR:

Magnetic Ink Character Recognition is a character recognition system that uses special ink and characters. When a document that contains this ink needs to be read, it passes through a machine, which magnetizes the ink and then translates the magnetic information into characters.

MICR technology is used by banks. Numbers and characters found on the bottom of checks (usually containing the check number, sort number, and account number) are printed using Magnetic Ink. To print Magnetic Ink need, you need a laser printer that accepts MICR toner.

MICR provides a secure, high-speed method of scanning and processing information.

OCR:

Often abbreviated OCR, optical character recognition refers to the branch of computer

science that involves reading text from paper and translating the images into a form that

the computer can manipulate (for example, into ASCII codes). An OCR system enables

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you to take a book or a magazine article, feed it directly into an electronic computer file,

and then edit the file using a word processor.

All OCR systems include an optical scanner for reading text, and sophisticated software

for analyzing images. Most OCR systems use a combination of hardware (specialized

circuit boards) and software to recognize characters, although some inexpensive

systems do it entirely through software. Advanced OCR systems can read text in large

variety of fonts, but they still have difficulty with handwritten text.

The potential of OCR systems is enormous because they enable users to harness the

power of computers to access printed documents. OCR is already being used widely in

the legal profession, where searches that once required hours or days can now be

accomplished in a few seconds.

OMR:

Short for optical mark recognition, the technology of electronically extracting intended data from marked fields, such as checkboxes and fill-infields, on printed forms. OMR technology scans a printed form and reads predefined positions and records where marks are made on the form. This technology is useful for applications in which large numbers of hand-filled forms need to be processed quickly and with great accuracy, such as surveys, reply cards, questionnaires and ballots. A common OMR application is the use of "bubble sheets" for multiple-choice tests used by schools. The student indicates the answer on the test by filling in the corresponding bubble, and the form is fed through an optical mark reader (also abbreviated as OMR, a device that scans the document and reads the data from the marked fields. The error rate for OMR technology is less than 1%.

Bar CODE:

The machine-readable representation of the UPC. Bar codes are read by a scanner that passes over the code and registers the UPC. The width of each black line and the subsequent white space between each line coincides with the numbers of the UPC.

Hard copy devices:

There are two major categories of hard copy devices.

i)Printers

ii)Plotters

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Difference Between Impact Printers And Non-impact Printers

What are printers? A printer is an output device that prints characters, symbols, and perhaps graphics on paper. The printed output is generally referred to as hardcopy because it is in relatively permanent form. Softcopy refers to temporary images such as those displayed on a monitor. Printers are categorized according to whether or not the image produced is formed by physical contact of the print mechanism with the paper. Impact printers have contact; nonimpact printers do not.

Impactprinters An impact printer has mechanisms resembling those of a typewriter. It forms characters or images by striking a mechanism such as a print hammer or wheel against an inked ribbon, leaving an image on paper. Impact printers are dying out; however, you may still come in contact with a dot-matrix printer. A dot-matrix printer contains a print head of small pins that strike an inked ribbon, forming characters or images. Print heads are available with 9, 18, or 24 pins; the 24-pin head offers the best print quality. Dot-matrix printers permit a choice between output of draft quality; a coarser-looking 72 dots per inch vertically, which may be acceptable for drafts of papers and reports, and near-letter-quality, a crisper-looking 144 dots per inch vertically, which is more suitable for a finished product to be shown to other people. Dot-matrix printers print about 40-300 characters per second (cps) and can print some graphics, although the reproduction quality is poor. Color ribbons are available for limited use of color. Dot-matrix printers are noisy, inexpensive, and they can print through multipart forms, creating several copies of a page at the same time, which ninimpact printers cannot do. Another type of impact printer is not used with microcomputers. Large computer installations use high-speed line printers, which print a whole line of characters at once rather a single character at a time. Some, called chain printers, contain characters on a rotating chain; others, called band printers, contain characters on a rotation band. Speeds of up to 3000 lines a minute may be possible with these machines.

Non-impact Printers:

Nonimpact printers, used almost everywhere now, are faster and quieter than impact printers because they have fewer moving parts. Nonimpact printers form characters and images without direct physical contact between the printing mechanism and the paper. Two types of nonimpact printers often used with microcomputers are laser printers and Ink-jet printers.

Laser Printer: Like a dot-matrix printer, a laser printer creates images with dots. However, as in a photocopying machine, these images are created on a drum, treated with a magnetically charged ink-like toner (powder), and then transferred from drum to

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paper. - There are good reasons why laser printers are so popular. They produce sharp, crisp images of both text and graphics, providing resolutions from 300 dpi up to 1200 dpi, which is near-typeset quality (NTQ). They are quiet and fast. They can print 4-32 text-only pages per minute for individual microcomputers, and more than 120 pages per minute for mainframes. (Pages with more graphics print more slowly.) They can print in many fonts (type styles and sizes). The more expensive models can print in different colors.

Laser printers have built-in RAM chips to store documents output from the computer. If

you are working in desktop publishing and printing complicated documents with color

and many graphics, you will need a printer with a lot of RAM. Laser printers also have

their own ROM chips to store fonts and their own small dedicated processor. To be able

to manage graphics and complex page design, a laser printer works with a page

description language, a type of software that has become a standard for printing

graphics on laser printers. A PDL (page description language) is software that describes

the shape and position of letters and graphics to the printer. PostScript, from Adobe

Systems, is one common type of page description language; HPGL, Hewlett-Packard

Graphic Language, is another.

Ink-jet printer: Like laser and dot-matrix printers, ink-jet printers also form images with little dots. Ink-jet printers spray small, electrically charged droplets of ink from four nozzles through holes in a matrix at high speed onto paper.

Ink-jet printers can print in color and are quieter and much less expensive than a color laser printer. However, they are slower and print in a somewhat lower resolution (300-720 dpi) than laser printers. Some new, expensive ink-jet printers print up 1200 or 1400 dpi. High resolution output requires the use of special coated paper, which costs more regular paper. And, if you are printing color graphics at a high resolution on an ink-jet printer, it may take 10 minutes or more for a single page finish printing.

A variation on ink-jet technology is the bubble-jet printer, which use miniature heating elements to force specially formulated inks through print heads with 128 tiny nozzles. The multiple nozzles print fine images at high speeds. This technology is commonly used in portable printers. Things to take into account when buying a printer, is the printer easy to set up? Easy to operate? Do I need color? or black will do? Does the manufacturer offer a good warranty and good telephone technical support? Otherwise it's wise to own your own personal printer and get to know the answer to these questions.

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Desk jet

DeskJet is a brand name for inkjet printers manufactured by Hewlett-Packard Company. These printers range from small domestic to large industrial models, although the largest models in the range have generally been dubbed Design Jet. The Macintosh-compatible equivalent was branded as the DeskWriter and competed with Apple's StyleWriter. The HP DeskJet 500 printer has four built-in typefaces and is compatible with TrueType fonts in Windows. The HP DeskJet 500 printer prints on plain paper with a print speed of up to three pages per minute.

HP developed thermal inkjet technology in 1979 and launched their Think Jet in 1984, with color following in 1987 thanks to the Paint Jet. Launched in February 1988, the HP DeskJet was the world’s first single-sheet, desktop printer.

A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. As with digital photocopiers and multifunction printers (MFPs), laser printers employ a xerographic printing process, but differ from analog photocopiers in that the image is produced by the direct scanning of a laser beam across the printer's photoreceptor.

A thermal transfer printer is a printer which prints on paper (or some other material) by melting a coating of ribbon so that it stays glued to the material on which the print is applied. It contrasts with direct thermal printing where no ribbon is present in the process. It was invented by SATO corporation around the late 1940s.

Usage of TT printers in industry includes:

• barcode labels (as labels printed with thermal printer tend not to last long), or for marking clothing labels (shirt size etc.)

• Printing plastic labels for chemical containers (because the cheaper types of plastic would melt in a laser printer)

Barcode printers typically come in fixed sizes of 4 inches, 6 inches or 8 inches wide. Although a number of manufacturers have made differing sizes in the past, most have now standardised on these sizes. The main application for these printers is to produce barcode labels for product and shipping identification.

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A barcode printer (or bar code printer) is a computer peripheral for printing barcode labels or tags that can be attached to physical objects. Barcode printers are commonly used to label cartons before shipment, or to label retail items with UPCs or EANs.

The most common barcode printers employ one of two different printing technologies. Direct thermal printers use a print head to generate heat that causes a chemical reaction in specially designed paper that turns the paper black. Thermal transfer printers also use heat, but instead of reacting the paper, the heat melts a waxy or resin substance on a ribbon that runs over the label or tag material. The heat transfers ink from the ribbon to the paper. Direct thermal printers are generally less expensive, but they produce labels that can become illegible if exposed to heat, direct sunlight, or chemical vapors.

Electrostatic printing: A process for printing or copying in which electrostatic forces are used to form the image in powder or ink directly on the surface to be printed.

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Unit–III

Languages High-level programming language:

A high-level programming language is a programming language with strong abstraction from the details of the computer. In comparison to low-level programming languages, it may use natural language elements, be easier to use, or be more portable across platforms. Such languages hide the details of CPU operations such as memory access models and management of scope.

This greater abstraction and hiding of details is generally intended to make the language user-friendly, as it includes concepts from the problem domain instead of those of the machine used. A high-level language isolates the execution semantics of a computer architecture from the specification of the program, making the process of developing a program simpler and more understandable with respect to a low-level language. The amount of abstraction provided defines how "high-level" a programming language is.

The first high-level programming language to be designed for a computer was Plankalkül, created by Konrad Zuse. However, it was not implemented in his time and his original contributions were isolated from other developments.

low level programming language:

Low-level programming language is a programming language that provides little or no abstraction from a computer's instruction set architecture. The word "low" refers to the small or nonexistent amount of abstraction between the language and machine language; because of this, low-level languages are sometimes described as being "close to the hardware."

Low-level languages can be converted to machine code without using a compiler or interpreter, and the resulting code runs directly on the processor. A program written in a

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low-level language can be made to run very fast, and with a very small memory footprint; an equivalent program in a high-level language will be more heavyweight. Low-level languages are simple, but are considered difficult to use, due to the numerous technical details which must be remembered.

By comparison, a high-level programming language isolates the execution semantics of computer architecture from the specification of the program, which simplifies development.

Low-level programming languages are sometimes divided into two categories: first generation, and second generation.

Software:

Computer software, or just software, is a collection of computer programs and related data that provide the instructions for telling a computer what to do and how to do it. In other words, software is a conceptual entity which is a set of computer programs, procedures, and associated documentation concerned with the operation of a data processing system. We can also say software refers to one or more computer programs and data held in the storage of the computer for some purposes. In other words software is a set of programs, procedures, algorithms and its documentation. Program software performs the function of the program it implements, either by directly providing instructions to the computer hardware or by serving as input to another piece of software. The term was coined to contrast to the old term hardware (meaning physical devices). In contrast to hardware, software is intangible, meaning it "cannot be touched" Software is also sometimes used in a more narrow sense, meaning application software only. Sometimes the term includes data that has not traditionally been associated with computers, such as film, tapes, and records.

Examples of computer software include:

• Application software includes end-user applications of computers such as word processors or video games, and ERP software for groups of users.

• Middleware controls and co-ordinates distributed systems. • Programming languages define the syntax and semantics of computer programs.

For example, many mature banking applications were written in the COBOL language, originally invented in 1959. Newer applications are often written in more modern programming languages.

• System software includes operating systems, which govern computing resources. Today large applications running on remote machines such as Websites are considered to be system software, because the end-user interface is generally through a graphical user interface, such as a web browser.

• Test ware is software for testing hardware or a software package. • Firmware is low-level software often stored on electrically programmable memory

devices. Firmware is given its name because it is treated like hardware and run ("executed") by other software programs.

• Shrink ware is the older name given to consumerwas often sold in retail stores in a

• Device drivers control parts of computers such as drives, or computer monitors

• Programming tools help conduct computing tasks in any category listed above. For programmers, these could be tools for older legacy systems in order to check

Types of software

Different types of computer softwareProgramming software, system softwaretypes of computer software used in computer networking. System software is the most commonly used variety types of softwareall software applications. It also provicomputers. System software coordinates all external devices of computer system like printer, keyboard, displays etc.

Programmers use the programming software to develop the programming languages necessary to run computer software. Compliers, interpreters, linkers and text editors are some of the basic tools used in programming software. commercial purpose. The application software is widely used in educational, business and medical fields. Computer games are the most popular forms of application software. Industrial automation, databases, business softwareof great help in the respective fields. Educational software is widely used in educational institutes

Hardware:

Shrink ware is the older name given to consumer-purchased software, because it was often sold in retail stores in a shrink-wrapped box.

control parts of computers such as disk drivescomputer monitors.

help conduct computing tasks in any category listed above. For programmers, these could be tools for debugging or reverse engineering

in order to check source code compatibility.

types of computer software are available in the global computer market. Programming software, system software and application software are the three main types of computer software used in computer networking. System software is the most

types of software. System software offers a protective shield to all software applications. It also provides support to the physical components of computers. System software coordinates all external devices of computer system like printer, keyboard, displays etc.

Programmers use the programming software to develop the programming languages mputer software. Compliers, interpreters, linkers and text editors are

used in programming software. Application software is used for commercial purpose. The application software is widely used in educational, business and medical fields. Computer games are the most popular forms of application software. Industrial automation, databases, business software and medical software prove to be of great help in the respective fields. Educational software is widely used in educational

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purchased software, because it

disk drives, printers, CD

help conduct computing tasks in any category listed above. reverse engineering

are available in the global computer market. and application software are the three main

types of computer software used in computer networking. System software is the most . System software offers a protective shield to

des support to the physical components of computers. System software coordinates all external devices of computer system like

Programmers use the programming software to develop the programming languages mputer software. Compliers, interpreters, linkers and text editors are

Application software is used for commercial purpose. The application software is widely used in educational, business and medical fields. Computer games are the most popular forms of application software.

and medical software prove to be of great help in the respective fields. Educational software is widely used in educational

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A personal computer is made up of multiple physical components of computer hardware, upon which can be installed a system software called an operating system, and a multitude of software applications to perform the operator's desired functions.

Though a PC comes in many different forms, a typical personal computer consists of a case or chassis in a tower shape (desktop), containing components such as a motherboard.

Firm ware:

In electronic systems and computing, firmware is a term often used to denote the fixed, usually rather small, programs and/or data structures that internally control various electronic devices. Typical examples of devices containing firmware range from end-user products such as remote controls or calculators, through computer parts and devices like hard disks, keyboards, TFT screens or memory cards, all the way to scientific instrumentation and industrial robotics. Also more complex consumer devices, such as mobile phones, digital cameras, synthesizers, etc., contain firmware to enable the device's basic operation as well as implementing higher-level functions.

Compiler:

A compiler is a computer program (or set of programs) that transforms source code written in a programming language (the source language) into another computer language (the target language, often having a binary form known as object code). The most common reason for wanting to transform source code is to create an executable program.

Interpretation:

Language interpretation is the facilitating of oral or sign-language communication, either simultaneously or consecutively, between users of different languages. The process is described by both the words interpreting and interpretation.

In professional parlance, interpreting denotes the facilitating of communication from one language form into its equivalent, or approximate equivalent, in another language form; while interpretation denotes the actual product of this work, that is, the message thus rendered into speech, sign language, writing, non-manual signals, or other language form. This important distinction is observed in order to avoid confusion.

An interpreter is a person who converts a thought or expression in a source language into an expression with a comparable meaning in a target language in "real time". The interpreter's function is to convey every semantic element (tone and register) and every intention and feeling of the message that the source-language speaker is directing to target-language recipients.

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Assembler:

Typically a modern assembler creates object code by translating assembly instruction mnemonics into opcodes, and by resolving symbolic names for memory locations and other entities. The use of symbolic references is a key feature of assemblers, saving tedious calculations and manual address updates after program modifications. Most assemblers also include macro facilities for performing textual substitution—e.g., to generate common short sequences of instructions as inline, instead of called subroutines.

Assemblers are generally simpler to write than compilers for high-level languages, and have been available since the 1950s. Modern assemblers, especially for RISC architectures, such as SPARC or POWER, as well as x86 and x86-64, optimize Instruction scheduling to exploit the CPU pipeline efficiently.

File Allocation Table:

File Allocation Table (FAT) is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of their relative simplicity. For floppy disks, the FAT has been standardized as ECMA-107 and ISO/IEC 9293.Those standards include only FAT12 and FAT16 without long filename support; long filenames with FAT is partially patented.

The FAT file system is relatively straightforward technically and is supported by virtually all existing operating systems for personal computers. This makes it a useful format for solid-state memory cards and a convenient way to share data between operating systems.

FAT32:

In order to overcome the size limit of FAT16, while at the same time allowing DOS (disk operating system) real mode code to handle the format, and without reducing available conventional memory unnecessarily, Microsoft expanded the cluster size yet again, calling the new revision FAT32. Cluster values are represented by 32-bit numbers, of which 28 bits are used to hold the cluster number, for a maximum of approximately 268 million (228) clusters. This allows for drive sizes of up to 8 TiB with 32 KiB clusters, but the boot sector uses a 32-bit field for the sector count, limiting volume size to 2 TiB on a hard disk with 512 byte sectors.

FAT32 was introduced with Windows 95 OSR2, although reformatting was needed to use it, and DriveSpace 3 (the version that came with Windows 95 OSR2 and Windows 98) never supported it. Windows 98 introduced a utility to convert existing hard disks from FAT16 to FAT32 without loss of data. In the NT line, native support for FAT32 arrived in Windows 2000. A free FAT32 driver for Windows NT 4.0 was available from

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Winternals, a company later acquired by Microsoft. Since the acquisition the driver is no longer officially available.

The maximum possible size for a file on a FAT32 volume is 4 GiB minus 1 byte or 4 294 967 295 (232−1) bytes. Video applications, large databases, and some other software easily exceed this limit. Larger files require another file system.

NTFS (New Technology File System) is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows 7.

NTFS supersedes the FAT file system as the preferred file system for Microsoft’s Windows operating systems. NTFS has several improvements over FAT and HPFS (High Performance File System) such as improved support for metadata and the use of advanced data structures to improve performance, reliability, and disk space utilization, plus additional extensions such as security access control lists (ACL) and file system journaling.

Algorithm:

In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning.

Starting from an initial state and initial input (perhaps null), the instructions describe a computation that, when executed, will proceed through a finite number of well-defined successive states, eventually producing "output" and terminating at a final ending state. The transition from one state to the next is not necessarily deterministic; some algorithms, known as randomized algorithms, incorporate random input

Flow chart:

Flowchart is a type of diagram that represents an algorithm or process, showing the steps as boxes of various kinds, and their order by connecting these with arrows. This diagrammatic representation can give a step-by-step solution to a given problem. Process operations are represented in these boxes, and arrows connecting them represent flow of control. Data flows are not typically represented in a flowchart, in contrast with data flow diagrams; rather, they are implied by the sequencing of operations. Flowcharts are used in analyzing, designing, documenting or managing a process or program in various fields.

Symbols:

A symbol is something such as a particular mark that represents some piece of information. For example, a red octagon may be a symbol for "STOP". On a map, a

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picture of a tent might represent a campsite. Numerals are symbols for numbers. All language consists of symbols. Personal names are symbols representing individuals.

Pseudo code:

Pseudocode is a compact and informal high-level description of a computer programming algorithm that uses the structural conventions of a programming language, but is intended for human reading rather than machine reading. Pseudocode typically omits details that are not essential for human understanding of the algorithm, such as variable declarations, system-specific code and subroutines. The programming language is augmented with natural language descriptions of the details, where convenient, or with compact mathematical notation. The purpose of using pseudocode is that it is easier for humans to understand than conventional programming language code, and that it is an efficient and environment-independent description of the key principles of an algorithm. It is commonly used in textbooks and scientific publications that are documenting various algorithms, and also in planning of computer program development, for sketching out the structure of the program before the actual coding takes place.

Memory system:

In computing, memory refers to the state information of a computing system, as it is kept active in some physical structure. The term "memory" is used for the information in physical systems which are fast (i.e. RAM), as a distinction from physical systems which are slow to access (i.e. data storage). By design, the term "memory" refers to temporary state devices, whereas the term "storage" is reserved for permanent data. Advances in storage technology have blurred the distinction a bit —memory kept on what is conventionally a storage system is called "virtual memory".

Colloquially, computer memory refers to the physical devices used to store data or programs (sequences of instructions) on a temporary or permanent basis for use in an electronic digital computer. Computers represent information in binary code, written as sequences of 0s and 1s. Each binary digit (or "bit") may be stored by any physical system that can be in either of two stable states, to represent 0 and 1. Such a system is called bistable. This could be an on-off switch, an electrical capacitor that can store or lose a charge, a magnet with its polarity up or down, or a surface that can have a pit or not. Today, capacitors and transistors, functioning as tiny electrical switches, are used for temporary storage, and either disks or tape with a magnetic coating, or plastic discs with patterns of pits are used for long-term storage.

Computer memory is usually meant to refer to the semiconductor technology that is used to store information in electronic devices. Current primary computer memory makes use of integrated circuits consisting of silicon-based transistors. There are two main types of memory: volatile and non-volatile.

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Random-access memory (RAM) is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in bursts, although the name DRAM / RAM has stuck. However, many types of SRAM, ROM, OTP, and NOR flash are still random access even in a strict sense. RAM is often associated with volatile types of memory (such as DRAM memory modules), where its stored information is lost if the power is removed. Many other types of non-volatile memory are RAM as well, including most types of ROM and a type of flash memory called NOR-Flash. The first RAM modules to come into the market were created in 1951 and were sold until the late 1960s and early 1970s. However, other memory devices (magnetic tapes, disks) can access the storage data in a predetermined order, because mechanical designs only allow this.

Hard disk:

A hard disk drive (HDD) is a non-volatile, random access digital data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the platters.

Introduced by IBM in 1956, hard disk drives have fallen in cost and physical size over the years while dramatically increasing in capacity. Hard disk drives have been the dominant device for secondary storage of data in general purpose computers since the early 1960s. They have maintained this position because advances in their areal recording density have kept pace with the requirements for secondary storage.

Scanner:

An image scanner—often abbreviated to just scanner— is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop (or flatbed) scanner where the document is placed on a glass window for scanning. Hand-held scanners, where the device is moved by hand, have evolved from text scanning "wands" to 3D scanners used for industrial design, reverse engineering, test and measurement, orthotics, gaming and other applications. Mechanically driven scanners that move the document are typically used for large-format documents, where a flatbed design would be impractical.

CD:

The Compact Disc (also known as a CD) is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage (CD-ROM), write-once audio and data storage (CD-R), rewritable media (CD-RW), Video Compact Discs (VCD), Super Video Compact

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Discs (SVCD), PhotoCD, PictureCD, CD-i, and Enhanced CD. Audio CDs and audio CD players have been commercially available since October 1982.

DVD:

DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than compact discs while having the same dimensions.

In Information Technology, a backup or the process of backing up refers to making copies of data so that these additional copies may be used to restore the original after a data loss event. The verb form is back up in two words, whereas the noun is backup (often used like an adjective in compound nouns).

Backups have two distinct purposes. The primary purpose is to recover data as a reaction to data loss, be it by data deletion or corrupted data. Data loss is a very common experience of computer users. 67% of internet users have suffered serious data loss. The secondary purpose of backups is to recover data from a historical period of time within the constraints of a user-defined data retention policy, typically configured within a backup application for how long copies of data are required. Though backups popularly represent a simple form of disaster recovery, and should be part of a disaster recovery plan, by themselves, backups should not alone be considered disaster recovery. Not all backup systems and/or backup applications are able to reconstitute a computer system, or in turn other complex configurations such as a computer cluster, active directory servers, or a database server, by restoring only data from a backup.

Since a backup system contains at least one copy of all data worth saving, the data storage requirements are considerable. Organizing this storage space and managing the backup process is a complicated undertaking. A data repository model can be used to provide structure to the storage. In the modern era of computing there are many different types of data storage devices that are useful for making backups. There are also many different ways in which these devices can be arranged to provide geographic redundancy, data security, and portability.

Before data is sent to its storage location, it is selected, extracted, and manipulated. Many different techniques have been developed to optimize the backup procedure. These include optimizations for dealing with open files and live data sources as well as compression, encryption, and de-duplication, among others. Many organizations and individuals try to have confidence that the process is working as expected and work to define measurements and validation techniques. It is also important to recognize the limitations and human factors involved in any backup scheme.

Back up:

In Information Technology, a backup or the process of backing up refers to making copies of data so that these additional copies may be used to restore the original after a

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data loss event. The verb form is back up in two words, whereas the noun is backup (often used like an adjective in compound nouns).

Backups have two distinct purposes. The primary purpose is to recover data as a reaction to data loss, be it by data deletion or corrupted data. Data loss is a very common experience of computer users. 67% of internet users have suffered serious data loss. The secondary purpose of backups is to recover data from a historical period of time within the constraints of a user-defined data retention policy, typically configured within a backup application for how long copies of data are required. Though backups popularly represent a simple form of disaster recovery, and should be part of a disaster recovery plan, by themselves, backups should not alone be considered disaster recovery. Not all backup systems and/or backup applications are able to reconstitute a computer system, or in turn other complex configurations such as a computer cluster, active directory servers, or a database server, by restoring only data from a backup.

Since a backup system contains at least one copy of all data worth saving, the data storage requirements are considerable. Organizing this storage space and managing the backup process is a complicated undertaking. A data repository model can be used to provide structure to the storage. In the modern era of computing there are many different types of data storage devices that are useful for making backups. There are also many different ways in which these devices can be arranged to provide geographic redundancy, data security, and portability.

Before data is sent to its storage location, it is selected, extracted, and manipulated. Many different techniques have been developed to optimize the backup procedure. These include optimizations for dealing with open files and live data sources as well as compression, encryption, and de-duplication, among others. Many organizations and individuals try to have confidence that the process is working as expected and work to define measurements and validation techniques. It is also important to recognize the limitations and human factors involved in any backup scheme.

External storage device:

External storage comprises devices that temporarily store information for transporting from computer to computer. Such devices are not permanently fixed inside a computer. Types of external storage devices .

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Unit–IV

Ms-Office

Microsoft Office is a proprietary commercial office suite of inter-related desktop applications, servers and services for the Microsoft Windows and Mac OS X operating systems, introduced by Microsoft in 1989. Initially a marketing term for a bundled set of applications, the first version of Office contained Microsoft Word, Microsoft Excel, and Microsoft PowerPoint. Over the years, Office applications have grown substantially closer with shared features such as a common spell checker, OLE data integration and Microsoft Visual Basic for Applications scripting language. Microsoft also positions Office as a development platform for line-of-business software under the Office Business Applications brand. According to Forrester Research, as of June 2009, some version of Microsoft Office is used in 80% of enterprises, with 64% of enterprises using Office 2007.

Navigating the Workspace: 1. The Ribbon - The Ribbon replaces the previous system of layered menus, toolbars, and task panes with a simpler system of interfaces optimized for

efficiency and discoverability

The set-up of the ribbon differs greatly from the earlier editions of Word, and requires its own vocabulary. Each of the words across the top (Home, Insert, Page Layout, etc) are called Tabs, Tabs open a Ribbon, within each Ribbon are Groups. When selecting some Groups, a unique Tab will appear (for example, the Design Tab). Tabs will differ depending on which Office program you’re using. 2. The Office Button - The Office Button, located in the upper left hand corner contains such options as:

• Save

• Save As

• Print

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• New

• Open 3. Customizing the Toolbar: The toolbar can be customized to include your favorite actions using the Quick Access Toolbar. Right-click any frequently used action (such as Paste) and choose “Add

to Quick Access Toolbar”.

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4. The Mac Interface: Instead of a Ribbon, Macs have a toolbar and formatting palettes

which contain the tools used to format and customize documents.

The formatting palette

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Microsoft Word: Some Basic Actions

To insert page breaks:

To insert pictures and graphics:

To insert headers and footers:

To track changes (useful for group projects):

Do a spelling and grammar check or word count:

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Ms Word:

Microsoft Word is a commercial word processor designed by Microsoft. It was first released in 1983 under the name Multi-Tool Word for Xenix systems. Subsequent versions were later written for several other platforms including IBM PCs running DOS (1983), the Apple Macintosh (1984), the AT&T Unix PC (1985), Atari ST (1986), SCO UNIX, OS/2, and Microsoft Windows (1989). It is a component of the Microsoft Office software system; it is also sold as a standalone product and included in Microsoft Works Suite. The current versions are Microsoft Word 2010 for Windows and 2011 for Mac.

Preparing documents and formatting:

To start Word, Click on Start>Programs>MSOffice>Word. A screen similar to the one below should appear:

Inserting Text:

To insert text you just type the text, new lines are created automatically for you by Word, and so you do not need to press the <Enter> key until you wish to start a new paragraph.

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The only time you will need to press the <Enter> is when you wish to start a new line such as at the end of a paragraph. (Paragraphs are defined by Word as all text up to the Enter character.)

Forcing a New Page:

To start a new page click on Insert then Break and then select page break. You can also use this if you want to move an automatically generated page break.

Moving the Cursor:

you miss out some text you can move the cursor, which is a vertical line showing your position in the text, to where you wish the text to start, and then type in the new text. To move the cursor, move the mouse pointer i.e. the Vertical bar, to the correct place and click the left mouse button.

Deleting Text:

If you make a mistake while entering text, pressing the <backspace> key will delete the last character typed. To correct other errors either move the cursor to the end of the text to be deleted and press <backspace> which deletes the character to the left of the cursor or move to the start of the text and press <Delete> which deletes the character to the right of the cursor. It is possible to delete text in larger quantities than character by character by selecting text (see below).

Selecting Text:

Many functions available in Word (for example deletions and formatting) only work on text which is selected, and not on the whole document. How to select text is described below. When you have selected text it is shown in reverse video (white on black).

WARNING When anything is selected, the next action applies to that text. IF YOU TYPE ANYTHING IT WILL REPLACE THE SELECTED TEXT. See Edit Undo below.

To select text with the mouse, either Drag across the text you want to select or move the mouse cursor to one end of the text you want to select and click, move to the other end of the block, then holding down the <Shift> key click the mouse button.

More specific blocks can be selected as follows:

A word Double-click the word.

A sentence Hold down <Ctrl> and click anywhere in the sentence.

A paragraph Double-click in the selection bar to the left of

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the paragraph.

A document Hold down the <Ctrl> key and click the selection bar, or, press Ctrl+A keys together.

The selection bar is the area to the left of the text on the screen. The mouse pointer changes to a right pointing arrow as you move into the selection bar.

To Unselect Text: Click the mouse pointer outside the selected area.

Undoing Mistakes:

If you make a mistake it is usually possible to undo the last edit by selecting Edit from the Menu and choosing Undo (the top choice, which changes to Undo Typing or Undo Formatting depending on what you have just done).

Cut, Copy and Paste:

Text can be moved or copied by selecting the relevant text, then Edit from the Menu bar and choosing either Cut (which removes the selected text from the document) or Copy which makes a copy of the text. It can then be re-inserted if required by moving the cursor to the new location, selecting Edit from the Menu and choosing Paste.

Three buttons on the toolbar (shown above) exist to enable you to perform these operations using the mouse. They consist of the Cut button showing a pair of scissors (cutting removes selected text and remembers it in something called the clipboard); the Copy button showing two identical pieces of paper (copy remembers the text without removing it); and the Paste button showing a clipboard with a piece of paper. (Pasting inserts the remembered text from the clipboard into the document where the cursor is. The text remains in the clipboard until it is replaced by some more text.)

To use these buttons simply select the required text for cut and copy or position the cursor for paste, point to them with the mouse and click the left button.

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Formatting Characters and Paragraphs:

The appearance of characters, (bold, italic, underline, etc.) and the format of paragraphs (justified, centered, etc.) can be changed in a number of ways. The most comprehensive range of options will be obtained by using the Format menu from the Menu Bar and then selecting Font or Paragraph (or indeed any of the other format choices). NOTE that the area to be formatted must first be selected.

The Format>Font Dialogue Box is shown below:

To use this box do the following:-

Click in any of the boxes in the Font Style area to turn on or off the feature. To change Size (measured in points), Colour, etc. choose from the list provided by pointing and clicking with the left-hand mouse button. The changes you make are illustrated in the Preview box, to apply them to the document click on OK, or if you decide not to make any changes click Cancel.

If you wish to change character spacing click on the character spacing tab.

Format Paragraph:

This option allows you to format the shape of paragraphs (left or right alligned, centred or justified), the amount of space before and after the paragraph, the line spacing

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withing the paragraph, any indents required (left, right or hanging). As with Format Font there is a Preview window to show you what effects your changes will have

Quick Formatting:

On the Formatting Toolbar (illustrated above) there are three buttons for character formatting, B for bold; I for italic and u for underlined; and there are four buttons for paragraph formatting which are marked with a picture of how that style of paragraph would appear; Left Aligned; Centred; Right Aligned and Justified. To use them, select the text to be formatted and click. With the character formatting buttons clicking the button again undoes the action. I.e. if the selected text is already Bold then clicking on the Bold button turns it back to normal.

Other format options include Borders & Shading and Bullets & Numbering.

MACROS:

A macro is a shortcut to a task you do repeatedly. Think about the Centre align operation. You first highlight the word you want centred, then click the centre icon in the toolbar. This is a macro. It's the short way of performing the centre task.

But you don't have to do it that way. There is a longer way. You can centre your text by clicking on Format from the menu bar. When the menu drops down, click Paragraph. You'll get a dialogue box popping up. Click the down arrow in the Alignment box, and then click on centre. Click OK on the dialogue box and your text is centred. That's the long way round.

Clicking the centre icon on the toolbar is much easier - it's a very useful Macro built in to Microsoft Word.

Ms Excel:

Microsoft Excel is a commercial spreadsheet application written and distributed by Microsoft for Microsoft Windows and Mac OS X. It features calculation, graphing tools, pivot tables, and a macro programming language called Visual Basic for Applications. It has been a very widely applied spreadsheet for these platforms, especially since version 5 in 1993, and it has almost completely replaced Lotus 1-2-3 as the industry standard for spreadsheets. Excel forms part of Microsoft Office. The current versions are 2010 for Microsoft Windows and 2011 for Mac OS X.

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Introduction Menus and Tools:

Menu Bar

The Menu bar is directly below the Title bar. Point with your mouse to a menu option and click the left mouse button. A drop-down menu will appear. To select an option, highlight the item on the drop-down menu and press Enter. An ellipse after a menu item signifies additional options.

Tool Bar

Toolbars provide shortcuts to menu commands. Toolbars are located just below the Menu bar.

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Function and chart:

Functions:

• One of the most highly useful features of Microsoft Excel is the function.

• Excel allows users to utilize a wide range of mathematical and trigonometric functions in their worksheets. Let’s see how to use functions in a worksheet using this simple Excel tutorial.

• Functions are predefined in MS Excel and we can be utilized easily. Some of the basic mathematical functions are SUM, AVERAGE, MAX, MIN, SQRT etc.

• Let’s take the SUM function for example. As the name suggests it is used to calculate the sum of values in different cells.

• To find the total of the values in cells A1, A2, A3 and A4, you will have to type in =A1+A2+A3+A4 in the formula bar or another cell.

• This could become tedious if you are attempting to find the total for many values. The same can be made simple by using the statement: ‘=SUM(A1:A4)’.

• The above statement instructs the processor to find the sum of all values from cell A1 to cell A4. This can be extended to any number of values.

• Similarly you can use the AVERAGE function to find the average of n values.

• SQRT stands for square root and this displays the square root of the value in a cell.

• For example let’s consider that the value in A3 is 64, the formula will be ‘=SQRT(A3)’ – so the output returned will be 8.

• Similarly, we can use many other mathematical functions and trigonometric functions like sin, cos, tan etc in our worksheet.

Charts:

Click the Chart Wizard button on the toolbar to open the Chart Wizard.

Suppose you're looking at a worksheet that shows how many cases of Sir Rodney's

Marmalade were sold by each of three salespeople in each of three months. How would

you create a chart to show how the salespeople compare against each other, every

month?

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To begin, you would select the data that you want to chart, as well as the column and

row labels.

Then you would click the Chart Wizard button on the toolbar to open the Chart

Wizard.

When the wizard opens, the Column chart type is selected. You could easily select

another chart type, but in this case you'd accept the Column type, which is commonly

used to compare items, and will get your point across.

Next you would click the Finish button at the bottom of the wizard.

Ms Power Point- Introduction:

Microsoft PowerPoint, usually just called PowerPoint, is a commercial presentation program developed by Microsoft. It is part of the Microsoft Office suite, and runs on Microsoft Windows and Apple's Mac OS X operating system

PowerPoint presentations consist of a number of individual pages or "slides". The "slide" analogy is a reference to the slide projector. Slides may contain text, graphics, sound,

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movies, and other objects, which may be arranged freely. PowerPoint, however, facilitates the use of a consistent style in a presentation using a template or "Slide Master".

The presentation can be printed, displayed live on a computer, or navigated through at the command of the presenter. For larger audiences the computer display is often projected using a video projector. Slides can also form the basis of webcasts.

PowerPoint provides three types of movements:

1. Entrance, emphasis, and exit of elements on a slide itself are controlled by what PowerPoint calls Custom Animations

2. Transitions, on the other hand are movements between slides. These can be animated in a variety of ways

3. Custom animation can be used to create small story boards by animating pictures to enter, exit or move.

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Menus and tools:

Menu bar:

To use a menu item, you click one of its words and the menu expands. If an item is missing from the main menu, you can customize it.

There are four main types of menus you will encounter:

When clicked, the behavior of a menu that stands alone depends on the actions prior to clicking it. Under the File menu, an example is Exit

A menu that is disabled is not accessible at the moment. This kind of menu depends on another action or the availability of something else. Here are examples:

A menu with three dots means that an intermediary action is required in order to apply its assignment. Usually, this menu would call a dialog box where the user would have to make a decision.

A menu with an arrow holds a list of menu items under it. A menu under another menu is called a submenu. To use such a menu, you would position the mouse on it to display its submenu. Here is an example:

On the main menu (and any menu), there is one letter underlined on each word. Examples are F in File, E in Edit, V in View, etc. The underlined letter is called an access key. The access key allows you to access the same menu item using the keyboard. In order to use an access key, the menu should have focus first. The menu is

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given focus by pressing either the Alt or the F10 keys. When the menu has focus and you want to dismiss it, you can press Esc.

On some menu items, there is a key or a combination of keys we call a shortcut. This key or this combination allows you to perform the same action on that menu using the keyboard. If the shortcut is made of one key only, you can just press it. If the shortcut is made of two keys, press and hold the first one, while you are holding the first, press the second key once and release the first key. Some shortcuts are a combination of three keys.

Press Means

T Press the T key

Alt, G Press and release Alt. Then press G

Ctrl + H Press and hold Ctrl. While you are still holding Ctrl, press H once. Then release Ctrl

Ctrl + Shift + E

Press and hold Ctrl. Then press and hold Shift. Then press E once. Release Ctrl and Shift

Tool bar:

Under the menu bar, there is another bar made of various buttons. This is called a toolbar. There are various toolbars used in Microsoft PowerPoint. Each toolbar has a proper name and we will learn how to recognize them.

At times, there will be many toolbars that come and go while you are using Microsoft PowerPoint. For this reason, we will refer to each toolbar by its name. To know the name of a toolbar, you can right-click any word on the menu bar or any button on the toolbar. If you have only one toolbar on your screen, its name will have a check box. The other name(s) on the context menu is (are) the one (those) you can add to the screen if you wish:

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Preparing Presentations:

Preparing a simple slide:

� Go to Insert, and click on New Slide. � Choose a layout (second one presented). � Type in slide’s title and slide’s text in boxes indicated. � To move box, use mouse to grab hash line (between little squares), and drag. � To resize height, drag a square on a horizontal border. � To resize width, drag a square on a vertical border. � To resize box in proportion, drag a square on a corner. � To add another text box, go to Insert, click on Text Box, then click and drag to

create new box.

Inserting and editing text:

� Go to Insert and choose Textbox from the drop down menu � Click on the slide and drag out with the mouse, creating a box � Type inside the box � To move the box, click and drag a side of the box. To resize the box, click and

drag a corner � Change the font size/shape/color by highlighting the text, then right clicking the

mouse. Use the options in the pop up menu to make your changes

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Inserting pictures and figures:

� To copy image from Internet to disk or hard drive:

• For PC, right-click mouse on Image, go to Save as, name image, Save to your disk or hard drive.

• For Mac, hold down Apple while clicking once on image, go to Save image as, name image, Save to your disk or hard drive.

� To insert image from File: Click on Insert, go to Picture, select From File. Locate image on drive or disk, and click Insert.

� To insert image from Clip Art: Click on Insert, go to Picture, select Clip Art. Choose image and click on Insert.

Making a Table:

� Go to Insert, click on New Slide, and choose the Table slide showing table. Click OK. (On an existing slide, Go to Insert, click on Table )

� Double click on table icon. � Choose numbers of rows and columns, and add one to each for data labels.

Select row or column, go to Table and click on Merge Cells for data labels.

Making a Graph (Chart):

� Click on Insert, then on Chart (or click on chart icon) � Click on Datasheet, and fill in the headings and data

Click on slide to return to slide with graph

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Unit–V

Internet

Introduction to Network:

A computer network can be two computers connected:

A computer network can also consist of, and is usually made for, more than two computers:

Characteristics of computer network:

The primary purpose of a computer network is to share resources:

1. You can play a CD music from one computer while sitting on another computer

2. You may have a computer with a CD writer or a backup system but the other computer doesn’t have it; In this case, you can burn CDs or make backups on a computer that has one of these but using data from a computer that doesn’t have a CD writer or a backup system

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3. You may have a computer that doesn’t have a DVD player. In this case, you can place a movie DVD on the computer that has a DVD player, and then view the movie on a computer that lacks a DVD player

4. You can connect a printer (or a scanner, or a fax machine) to one computer and let other computers of the network print (or scan, or fax) to that printer (or scanner, or fax machine)

5. You can place a CD with pictures on one computer and let other computers access those pictures

6. You can create files and store them in one computer, then access those files from the other computer(s) connected to it

Types:

One way to categorize the different types of computer network designs is by their scope or scale. For historical reasons, the networking industry refers to nearly every type of design as some kind of area network. Common examples of area network types are:

1. LAN - Local Area Network 2. WLAN - Wireless Local Area Network 3. WAN - Wide Area Network 4. MAN - Metropolitan Area Network 5. SAN - Storage Area Network, System Area Network, Server Area Network, or

sometimes Small Area Network 6. CAN - Campus Area Network, Controller Area Network, or sometimes Cluster

Area Network 7. PAN - Personal Area Network 8. DAN - Desk Area Network

Concepts of World Wide Web:

The World Wide Web (abbreviated as WWW or W3 and commonly known as the Web), is a system of interlinked hypertext documents accessed via the Internet. With a web browser, one can view web pages that may contain text, images, videos, and other multimedia and navigate between them via hyperlinks

Usage of world wide web:

They are:

1. Inexpensive. They do not use paper and they are usually free for use by the students

2. Searchable.� Search engines are readily available and can be incorporated into

WWW sites so that the entire resource can be searched by key word or phrase.

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3. Authoritative. Most textbooks are the product of one individual's heroic efforts. They are limited by the author's expertise and time available for research and production, and they are often are out of date before they are used. In contrast, with the WWW it is possible for environmental scientists and educators everywhere to collaborate in producing curriculum and virtual textbooks, taking advantage of special scientific, legal and political expertise as well as local knowledge everywhere. Such a resource could dramatically improve the quality of instruction, wherever it is used.

4. Up to date. The WWW links provide access to sources of information, analysis, and opinion that are constantly being updated, without the need for instructor involvement. For example, pending federal and state legislation is one important type of information that is usually readily available via the Web. The Thomas Home Page (http://thomas.loc.gov/home/thomas.html) provides comprehensive information on bills before Congress, with digests that are usually available within 48 hours of the introduction of the bill.

5. Interactive. Some WWW sites allow various types of interaction with the user. Examples are self-paced tutorials (for example, the tutorial on Geographic Information Systems at http://www.uwsp.edu/acaddept/geog/index.htm), simulations, and virtual field trips and expeditions .With our sites we encourage students to contribute to the sources of information, as well as use them. For example, they are asked to identify non-functional links, to explore internet resources not already identified in our site, and to propose additional links for evaluation and incorporation into the hypertext book if appropriate. By its nature the internet provides an outstanding opportunity for conservationists in different parts of the world to share information and experience. It also lends itself to the establishment and management of geographic information systems in which numerous sources of local information can be integrated into global databases.

6. Unlimited and Evolving: Since the information on the WWW is distributed over a huge number of computers, the amount of information that is accessible is enormous and growing rapidly. In contrast, conventional textbooks are necessarily limited in scope.

7. Available and Accessible: Web documents can be made available to the world for educational and other purposes without cost or restriction. This makes them ideal information sources for on-line courses.

Creating e-mail id:

Email has become a standard form of everyday communication for people all over the world, and Gmail is one of the most popular email services. The step-by-step procedure is give as follows:

1. Go to required website and click the "Create an account" button .

2. Fill out the requested personal details such as your first and last name.

3. Place your desired login name information on the account form. The login name

will be your email address. Click on the "Check Availability" button to see if your

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desired login name is available. It might take several tries until you find a login

name that is available.

4. Choose a password based on the criteria. There is a bar to the right that will give

you an idea of the strength of your password.

5. Choose a security question from the drop-down menu. There are several options

available, so try to choose one that few people would know.

6. Provide an existing email address in the "Secondary Email" field. If you do not

have another email address, this field can be left blank. Any email address you list

will be used to verify the new address or address any login information you might

forget in the future.

7. Type the characters from the word-verification text into the appropriate field.

8. Click on the "Create My Account" button. Review the terms and conditions--you

can only create an account by agreeing to them. By clicking on the "Create My

Account" button, you automatically agree to the terms of Gmail.

9. Click on the "Show Me My Account" button to view your newly created account.

Sending mail:

Compose a email by click on the compose botton on the web page.Once you have written your email, and are ready to send it you simply click on the Send button. By deafult copy of all emails will send in a folder called sent.

Receving mail:

Mail stores email messages in mail folders. Initially, all of your incoming email

messages arrive in your inbox folder(except suspected spams, which goes directly to

the spam folder). To read a message just click on the inbox, will show the unread

messages.

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A list of unread messages in your inbox appears in the top of the inbox tab.

The subject of the messages will give you an idea of what each one is about.

Chatting:

On the Internet, chatting is talking to other people who are using the Internet at the same time you are. Usually, this "talking" is the exchange of typed-in messages requiring one site as the repository for the messages (or "chat site") and a group of users who take part from anywhere on the Internet. In some cases, a private chat can be arranged between two parties who meet initially in a group chat. Chats can be ongoing or scheduled for a particular time and duration. Most chats are focused on a particular topic of interest and some involve guest experts or famous people who "talk" to anyone joining the chat. (Transcripts of a chat can be archived for later reference.)

Chats are conducted on online services (especially America Online), by bulletin board services, and by Web sites. Several Web sites, notably Talk City, exist solely for the purpose of conducting chats. Some chat sites such as Worlds Chat allow participants to assume the role or appearance of an avatar in a simulated or virtual reality environment.

Talk City and many other chat sites use a protocol called Internet Relay Chat.

A chat can also be conducted using sound or sound and video, assuming you have the bandwidth access and the appropriate programming.

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Types of chatting:

1. text-based chat:

One of the most popular is instant messaging. Take a look at the text-based chat capabilities with Instant Messenger. This type of chat can be used in a one-on-one buddy situation or with multiple buddies

2. audio and visual based chat:

This type of chat requires a camera, microphone to send audio chat and speakers to receive audio chat. CNET provides several cautions about this type of chat:

• This type of chat is computer resource intensive, so check system requirements carefully before investing in the equipment needed to share in this type of chat.

• Remember that this type of chat allows you not only to speak to strangers in your own voice, but be seen by strangers as well.

Blogs:

A blog (a blend of the term web log) is a type of website or part of a website. Blogs are usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video. Entries are commonly displayed in reverse-chronological order. Blog can also be used as a verb, meaning to maintain or add content to a blog.

Most blogs are interactive, allowing visitors to leave comments and even message each other via widgets on the blogs and it is this interactivity that distinguishes them from other static websites.

Many blogs provide commentary or news on a particular subject; others function as more personal online diaries. A typical blog combines text, images, and links to other blogs, Web pages, and other media related to its topic. The ability of readers to leave comments in an interactive format is an important part of many blogs. Most blogs are primarily textual, although some focus on art (art blog), photographs (photoblog), videos (video blogging), music (MP3 blog), and audio (podcasting). Microblogging is another type of blogging, featuring very short posts.

Types:

There are many different types of blogs, differing not only in the type of content, but also in the way that content is delivered or written.

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Personal blogs

The personal blog, an ongoing diary or commentary by an individual, is the traditional,

most common blog. Personal bloggers usually take pride in their blog posts, even if their

blog is never read. Blogs often become more than a way to just communicate; they

become a way to reflect on life, or works of art. Blogging can have a sentimental quality.

Few personal blogs rise to fame and the mainstream but some personal blogs quickly

garner an extensive following. One type of personal blog, referred to as a microblog, is

extremely detailed and seeks to capture a moment in time. Some sites, such as Twitter,

allow bloggers to share thoughts and feelings instantaneously with friends and family,

and are much faster than emailing or writing.

Corporate and organizational blogs

A blog can be private, as in most cases, or it can be for business purposes. Blogs used

internally to enhance the communication and culture in a corporation or externally for

marketing, branding or public relations purposes are called corporate blogs. Similar

blogs for clubs and societies are called club blogs, group blogs, or by similar names;

typical use is to inform members and other interested parties of club and member

activities.

Forums:

An Internet forum, or message board, is an online discussion site where people can hold conversations in the form of posted messages. They differ from chat rooms in that messages are at least temporarily archived. Also, depending on the access level of a user and/or the forum set-up, a posted message might need to be approved by a moderator before it becomes visible.

Forums have a specific set of jargon associated with them; e.g. a single conversation is called a "thread".

A forum is hierarchical or tree-like in structure: a forum can contain a number of subforums, each of which may have several topics. Within a forum's topic, each new discussion started is called a thread, and can be replied to by as many people as wish to.

Depending on the forum's settings, users can be anonymous or have to register with the forum and then subsequently log in in order to post messages. On most forums, users do not have to log in to read existing messages.

Rss:

RSS (originally RDF Site Summary, often dubbed Really Simple Syndication) is a family of web feed formats used to publish frequently updated works—such as blog

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entries, news headlines, audio, and video—in a standardized format. An RSS document (which is called a "feed", "web feed",or "channel") includes full or summarized text, plus metadata such as publishing dates and authorship.

RSS feeds benefit publishers by letting them syndicate content automatically. A standardized XML file format allows the information to be published once and viewed by many different programs. They benefit readers who want to subscribe to timely updates from favored websites or to aggregate feeds from many sites into one place.

RSS feeds can be read using software called an "RSS reader", "feed reader", or "aggregator", which can be web-based, desktop-based, or mobile-device-based. The user subscribes to a feed by entering into the reader the feed's URI or by clicking a feed icon in a web browser that initiates the subscription process. The RSS reader checks the user's subscribed feeds regularly for new work, downloads any updates that it finds, and provides a user interface to monitor and read the feeds. RSS allows users to avoid manually inspecting all of the websites they are interested in, and instead subscribe to websites such that all new content is pushed onto their browsers when it becomes available.

Example:

As RSS files are essentially XML formatted plain text, the RSS file itself is relatively easily read both by automated processes and by humans alike. An example file could have contents such as the following. This could be placed on any appropriate communication protocol for file retrieval, such as http or ftp, and reading software would use the information to present a neat display to the end user.

<?xml version="1.0" encoding="UTF-8" ?>

<rss version="2.0">

<channel>

<title>RSS Title</title>

<description>This is an example of an RSS feed</description>

<link>http://www.someexamplerssdomain.com/main.html</link>

<lastBuildDate>Mon, 06 Sep 2010 00:01:00 +0000 </lastBuildDate>

<pubDate>Mon, 06 Sep 2009 16:45:00 +0000 </pubDate>

<item>

<title>Example entry</title>

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<description>Here is some text containing an interesting

description.</description>

<link>http://www.wikipedia.org/</link>

<guid>unique string per item</guid>

<pubDate>Mon, 06 Sep 2009 16:45:00 +0000 </pubDate>

</item>

</channel>

</rss>

Feedback:

Feedback describes the situation when output from (or information about the result of) an event or phenomenon in the past will influence an occurrence or occurrences of the same (i.e. same defined) event / phenomenon (or the continuation / development of the original phenomenon) in the present or future. When an event is part of a chain of cause-and-effect that forms a circuit or loop, then the event is said to "feed back" into itself.

Types of feedback:

1. Positive feedback:

Positive feedback tends to increase the event that caused it, such as in a nuclear chain-reaction. It is also known as a self-reinforcing loop. An event influenced by positive feedback can increase or decrease its output/activation until it hits a limiting constraint. Such a constraint may be destructive, as in thermal runaway or a nuclear chain reaction. Self-reinforcing loops can be a smaller part of a larger balancing loop, especially in biological systems such as regulatory circuits.

2. Negative feedback:

Negative feedback, which tends to reduce the input signal that caused it, is also known as a self-correcting or balancing loop.Such loops tend to be goal-seeking, as in a thermostat, which compares actual temperature with desired temperature and seeks to reduce the difference. Balancing loops are sometimes prone to hunting: an oscillation caused by an excessive or delayed negative feedback signal, resulting in over-correction, wherein the signal becomes a positive feedback.

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The terms negative and positive feedback can be used loosely or colloquially to describe or imply criticism and praise, respectively. This may lead to confusion with the more technically accurate terms positive and negative reinforcement, which refer to something that changes the likelihood of a future behaviour. Moreover, when used technically, negative feedback leads to stability that is, in general, considered good, whereas positive feedback can lead to unstable and explosive situations that are considered bad. Thus, when used colloquially, these terms imply the opposite desirability to that when used technically.

Negative feedback was applied by Harold Stephen Black to electrical amplifiers in 1927, but he could not get his idea patented until 1937. Arturo Rosenblueth, a Mexican researcher and physician, co-authored a seminal 1943 paper Behavior, Purpose and Teleologythat, according to Norbert Wiener (another co-author of the paper), set the basis for the new science cybernetics. Rosenblueth proposed that behaviour controlled by negative feedback, whether in animal, human or machine, was a determinative, directive principle in nature and human creations.[citation needed] This kind of feedback is studied in cybernetics and control theory.

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