info tech - ipcc unit 1

IPCC – Information Technology– Unit -1 CA – IPCC

Paper: 7A Information Technology

Study Tips and Examination Technique

The aim of this section is to provide general guidance as to how to study for your exams. The guidance

given herein is supplementary to the manner of study followed by you and is intended to improve your

existing technique, and aims to give ideas on how to improve your existing study techniques. However,

it is essential that you adopt methods and techniques with which you feel comfortable.

Passing exams is partly a matter of intellectual ability, however accomplished you are in that

respect you can improve your chances significantly by the use of appropriate study and revision

techniques. In this section, we briefly outline some tips for effective study during the earlier stages

of preparation.

Know Your Syllabus

Go through the syllabus carefully

The study material is divided in following six chapters/topics based on the syllabus.

o Introduction to computer

o Data storage, Retrieval and Data Base Management Systems.

o Computer networks & Network security

o Internet and other technologies

o Introduction to flowcharting

o Decision Table

Understand the linkages between chapters at macro-level.

Plan Your Study

Make a study plan covering the entire syllabus and then decide how much time you can allocate to

the subject on daily/weekly basis.

Allocation of time must be done keeping in view your office commitments as well as social needs

and personal hobbies.

Maintain the time balance amongst various subjects such as purely descriptive type and numerical-

based papers. Allocate time in such a manner that your interest is well sustained and you are able to

score well in the final examination as well.

Always assess your preparation periodically, say, on monthly basis. If necessary, revise your plan

and allocate more time for the subjects in which you feel deficient.


Prepare Study Strategy

Read, understand and assimilate each chapter.

First of all, have an overview of the chapter to understand the broad contents and sequence of vari-

ous sub-topics.

Do the introspection while going through the chapter and ask various questions to yourself.

Read each chapter slowly to ensure that you understand and assimilate the main concept. If need be,

read once again with concentration and then try to attempt exercises at the end of the chapter or giv-

en in the Practice Manual.

Recapitulate the main concept after going through each chapter by way of brief notes.

Prepare notes in the manner you feel comfortable covering all key points

One may use highlighter/underlining the significant points or writing down in the margin.

Your conceptual clarity of the topic will be reflected in your ability to attempt the questions given

in the exercises as well as in the practice manual. Make a serious attempt at producing your own an-

swers but at this stage do not be much concern about attempting the questions in examination based

conditions. At initial stages, it is more important to understand and absorb the material thoroughly

rather than to observe the time limits that would apply in the actual examination conditions.

Always try to attempt the past year examination question papers under examination Conditions

Revision of material should never be selective in any case. Broad coverage of the entire syllabus is

more important than preparing 2-3 chapters exhaustively.

Repeatedly read through the text along with your notes carefully. Try to remember the definition

and important aspects of the related topics.

Examination Technique

Reach examination hall well in time.

Plan your time so that equal time is awarded for each mark. Keep sometime for revision as well.

Always attempt to do all questions. Remember that six average answers fetch more marks than five

best answers. Therefore, it is important that you must finish each question within allocated time.

Read the question carefully more than once before starting the answer to understand very clearly as

to what is required by the paper-setter.

Always be concise and write to the point and do not try to fill pages unnecessarily.

In case a question is not clear, you may state your assumptions and then answer the question.

While writing answers in respect of essay-type questions, try to make sub-headings so that it catch-

es the examiner’s eye. In case of case-study, be very precise and write your conclusion in a clear

manner.

Revise your answers carefully and underline important points before leaving the examination hall.

Wishing you all the Best


Information Technology (50 Marks)

1) Introduction to Computers

2) Input and Output Devices

3) Computer Software

4) Data Storage, Retrieval and DBMS

5) Computer Networks & Network Security

6) Internet and Other technologies

7) Flow charts

8) Decision Tables

Strategic Management (50 Marks)

1) Business Environment

a) General Environment – Demographic, Socio-cultural, Macro-economic, Legal/political

b) Competitive Environment

2) Business Policy and Strategic Management

Meaning and nature; Vision, Mission and Objectives; Strategic levels in organizations.

3) Strategic Analyses

Situational Analysis – SWOT Analysis, TOWS Matrix, Portfolio Analysis – BCG Matrix.

4) Strategic Planning

Meaning, stages, alternatives, strategy formulation

5) Formulation of Functional Strategy

Marketing Strategy, Financial strategy, Production strategy, Logistics strategy, Human resource

strategy.

6) Strategy Implementation and Control

Organizational Structures; Establishing Strategic business units etc.

7) Reaching Strategy Edge

Business process Reengineering, Benchmarking, TQM, Six Sigma etc.


Chapter-1

Introduction to Computers

Scope of this chapter: -

Generation of Computers and their evolution

Classification of computers.

Features of computers, their advantages and limitations

Basic components of a computer system.

Types of Storage devices, their use and capacity.

Types of RAM and their working.

1.1 Historical Development of Computers

The modern computer with the power and speed of today was not a solitary invention that sprang com-

pleted from the mind of a single individual. It is the end result of countless inventions, ideas, and de-

velopments contributed by many people throughout the last several decades.

The history of the modern computer begins with two separate technologies—automated calculation and

programmability. An example of early mechanical calculating devices was abacus.

The abacus was an early aid for mathematical computations. With abacus a person can work on

addition and subtraction problems at the speed of a person equipped with a hand calculator (multiplica-

tion and division are slower). The device is capable to perform simple addition and subtraction rapidly

and efficiently by positioning the ring on a wooden rack holding two horizontal wires with beads

strung on them. When these beads are moved around, according to programming rules memorized by

the user, all regular arithmetic problems can be done.


The first mechanical digital calculating machine was built in 1642 by the French scientist philoso-

pher Blaise Pascal. And since then the ideas and inventions of many mathematicians, scientists, and

engineers paved the way for the development of the modern computer in following years.

In 1671, Gottfried Wilhelm Von Leibniz invented a computer that was built in 1694. It could add and

multiply, after changing some things around. Leibniz invented a special stepped gear mechanism for

introducing the addend digits, and this is still being used.

Thomas of Colmar (A.K.A. Charles Xavier Thomas) created the first successful mechanical calcula-

tor that could add, subtract, multiply, and divide. A lot of improved desktop calculators were mainly

made for commercial users, and not for the needs of science. First commercially successful calculator,

for almost 40 years 1851 to 1887 Arithmometer was the only type of mechanical calculator.

In 1801, Joseph Marie Jacquard made an improvement to the textile loom by introducing a series of

punched paper cards as a template which allowed his loom to weave intricate patterns automatically.


The resulting Jacquard loom was an important step in the development of computers because the use

of punched cards to define woven patterns can be viewed as an early, albeit limited, form of program-

mability.

It was the fusion of automatic calculation with programmability that produced the first recognizable

computers. In 1837, Charles Babbage was the first to conceptualize and design a fully programmable

mechanical computer. Babbage was a mathematician who taught at Cambridge University in England.

He began planning his calculating machine calling it the Analytical Engine. The idea for this ma-

chine was amazingly like the computer we know today. It was to read a program from punched cards

(two types of cards, one for instructions other to input data), carry out the process and store the answers

to different problems, and print the answer on paper.

In the late 1880s, Herman Hollerith invented the recording of data on a machine readable medium.

After some initial trials with paper tape, he settled on punched cards. To process these punched

cards, he invented the tabulator, and the keypunch machines. These three inventions were the

foundation of the modern information processing industry. Large-scale automated data processing of

punched cards was performed for the 1890 United States Census by Hollerith's company, which later

became the core of IBM. (the census were finished in one year where as census for 1880 took almost 8

years by manual tabulating) By the end of the 19th

century a number of technologies that would later

prove useful in the realization of practical computers had begun to appear: the punched card, Boolean

algebra, the vacuum tube (thermionic valve) and the teleprinter.

In 1944, IBM Automatic Sequence Controlled Calculator (ASCC), called the Mark I was devel-

oped at Harvard University by Howard H. Aiken, was an electro-mechanical computer which would

automatically sequence the operations and calculations performed. It was very reliable, much more so

than early electronic computers. The Mark I computer was very much like the design of Charles Bab-

bage's having mainly mechanical parts, but with some electronic parts. His machine was designed to be


programmed to do many computer jobs. This all-purpose machine is what we now know as the PC or

personal computer. The Mark I was the first computer financed by IBM and was about 50 feet long and

8 feet tall. It used mechanical switches to open and close its electric circuits. It contained over 500

miles of wire and 750,000 parts. It has been described as "the beginning of the era of the modern com-

puter" and "the real dawn of the computer age".

ENIAC, short for Electronic Numerical Integrator And Computer, was the first general-purpose,

electronic computer built in 1946 by J. Presper Eckert and John Mauchly. It was complete digital

computer capable of being reprogrammed to solve a full range of computing problems. It boasted

speeds one thousand times faster than electromechanical machines, a leap in computing power that no

single machine has since matched. This mathematical power, coupled with general-purpose program-

mability, excited scientists and industrialists.

The ENIAC was a modular computer, composed of individual panels to perform different functions.

Twenty of these modules were accumulators, which could not only add and subtract but hold a ten-digit

decimal number in memory. Numbers were passed between these units across a number of general-

purpose buses, or trays, as they were called. In order to achieve its high speed, the panels had to send

and receive numbers, compute, save the answer, and trigger the next operation—all without any

moving parts. Key to its versatility was the ability to branch; it could trigger different operations that

depended on the sign of a computed result.

The size of ENIAC‘s numerical “word” was 10 decimal digits, and it could multiply two of these num-

bers at a rate of 300 per second, by finding the value of each product from a multiplication table stored

in its memory. ENIAC was therefore about 1,000 times faster than the previous generation of relay

computers. ENIAC used 18,000 vacuum tubes; about 1,800 square feet of floor space, and consumed

about 180,000 watts of electrical power. It had punched card I/O, 1 multiplier, 1 divider/square root-

er, and 20 adders using decimal ring counters, which served as adders and also as quick-access (.0002

seconds) read-write register storage. ENIAC is commonly accepted as the first successful high – speed

electronic digital computer (EDC) and was used from 1946 to 1955.

Modern type computer began with John von Neumann's development of software written in bi-

nary code. It was Von Neumann who began the practice of storing data and instructions in binary code


and initiated the use of memory to store data, as well as programs. A computer called the EDVAC

(Electronic Discrete Variable Computer) was built using binary code in 1950. Before the EDVAC,

computers like the ENIAC could do only one task then they had to be rewired to perform a differ-

ent task or program. The EDVAC's concept of storing different programs on punched cards instead of

rewiring computers led to the computers that we know today.

1.2 Generation of Computers and their evolution

The modern computer with the power and speed of today was not a solitary invention that sprang com-

pleted from the mind of a single individual. Many people contributed their ideas, inventions and devel-

opments to the present computer what we see.

The history of computer development is often referred to in reference to the different generations of

computing devices. A generation refers to the state of improvement in the product development pro-

cess. This term is also used in the different advancements of new computer technology. With each new

generation, the circuitry has gotten smaller and more advanced than the previous generation before it.

As a result of the miniaturization, speed, power, and computer memory has proportionally increased.

New discoveries are constantly being developed that affect the way we live, work and play.

We can compare the evolution of computer with the Mobiles, initial mobiles use to be big in size and

without no camera and it is used only for the purpose of talking between people, but the latest mobiles

are very sleek in size and with high end technology inbuilt in them like Cameras, Video Recording,

Voice Recognition and Internet etc,.

We shall read about each generation and the developments that led to the current devices that we use

today.

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First Generation


First Generation Computers: UNIVAC (Universal Automatic Computer) was the first computer

commercially available and marks the beginning of first generation of electrical computers. These

computer systems are made of Vacuum Tubes. The input and output units were the punched card read-

er and the card punches.

Below is the picture of Magnetic Drum Memory & UNIVAC Computer

Below is a sample picture of Punched cards

Features:

1. Computers were large in size (25 feet by 50 feet; 5600 tubes)

Third Genera-

tion Computers

(1964-1971)

Fifth Generation

Computers (1990

and beyond)

Second Genera-

tion Computers

(1956-1963)

Fourth Generation

Computers (1972-

1990)


2. These computers uses vacuum tube for data processing and storage, Cannot be relied completely

as the vacuum tubes burned out during operations.

3. Requires Air Conditioning due to the high level of heat generation.

4. They had a memory size of 20 bytes and speed of 5 mbps

5. They use punch card for data storage.

6. The programmers were machine dependent.

7. Lower Internal Storage capacity (Magnetic Drums).

8. High consumption of Electric power.

9. Low speed of processing due to the low speed of input and output devices (Punched Cards).

10. Use of Low level language (Machine language).

Second Generation Computers: These computers used Transistors instead of Vacuum tubes. Tran-

sistors were invented in 1947 but seen widespread only from 1950’s IBM 1401 was the most popular

second – generation computer.

The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster,

cheaper, more energy-efficient and more reliable than their first-generation predecessors.

These were also the first computers that stored their instructions in their memory, which moved from a

magnetic drum to magnetic core technology. The first computers of this generation were developed for

the atomic energy industry.

Features:

1. They were capable of translating, process and store data.

2. They were much smaller in size than first generation computers.

3. They had got memory size of 32 bytes and speed of 10 mbps, high processor speed.

4. Generated low level of heat and required less power.

5. Greater degree of reliability.

6. They use punch card for data storage.

7. Moved from Machine language to Assembly language and also initial high level language like

COBOL and FORTRAN.

Due to use of high level language and high level of operating system the computers were used by varie-

ty of users like by commercial users and scientific users.


Third Generation Computers:

Third Generation computers were built using the new technology called Integrated Circuits (IC).

The ICs are silicon chips which are tiny in size; contain thousands of individual components integrated

in a small chip. Thus the computers were compact, faster, more reliable, required less power and low

cost.

These computers can be used for both Scientific and business applications.

Features:

1. They were much more powerful and smaller in size than second generation computers.

2. They used integrated circuit (I.C.) to store data which consisted of many transistors, increased pro-

cessing speed.

3. The hardware cost and maintenance cost was much lower than second generation of computer.

4. They were generally used for business and scientific purposes

5. They uses storage disk for data storage e.g. magnetic disks, tapes.

6. Third generation computers were more reliable compared to other previous generations.

7. The operating systems were introduced in this era.

8. In this generation, high level programming languages were used. For e.g. Fortran, COBOL, PAS-

CAL and BASIC.

9. Third generation computers permit Multi Programming and Time Sharing.

Fourth Generation computers: Fourth generation machines appeared in 1970’s utilizing still newer

technology which enabled to be even smaller and faster than third generation computers.


The IC technology in the third generation was mainly MSI (Medium scale integration), where as the

fourth generation computer adopted the IC technology with LSI (Large Scale Integration) and VLSI

(Very Large scale Integration), further gone for ULSI.

The microprocessor brought the fourth generation of computers, as thousands of integrated circuits

were built onto a single silicon chip that contains a CPU. In the world of personal computers, the terms

microprocessor and CPU are used interchangeably.

Three basic characteristics differentiate microprocessors are:

Instruction Set: The set of instructions that the microprocessor can execute.

Bandwidth: The number of bits processed in a single instruction.

Clock Speed: Given in megahertz (MHz), the clock speed determines how many instructions per

second the processor can execute.

Micro computers are fully assembled computer into single machine, which consisted of Keyboard, pro-

cessor unit, CRT and built in cassette tape recorder.

IBM PC, with the introduction of personal computer by IBM in 1981, and apple introduced the Macin-

tosh in 1984, individuals also started buying the computers for their personal uses, thus computers

stepped out of large organisations and entered into homes.

Features:

1. More compact and smaller in size than the third generation computers.

2. Use of LSI and VLSI technology of Integrated Circuits.

3. Enhanced capability of input and output devices.

4. Introduction of Micro Computers and Personal Computers.

5. Computers are designed with graphical user interface which is user friendly.

6. Use of Hard disk as storage device, which are also available in the sizes of 80 GB to 500 GB and

Terra bytes.

7. Technology of Networks LAN (Local Area Network) and Wan (Wide Area Network) is used for

information accessing and sharing.

8. Very High speed of Microprocessor.

9. Use of Object oriented programming languages (OOPs)like Java, C++ have made the software

more reliable and efficient.


Fifth Generation Computers: Fifth generation computing devices, based on artificial intelligence, are

still in development, though there are some applications, such as voice recognition, that are being used

today.

Artificial Intelligence is the branch of computer science concerned with making computers behave like

humans. The term was coined in 1956 by John McCarthy. Artificial intelligence includes:

Features:

1. Games Playing: Programming computers to play games like chess and checkers.

2. Expert System: Programming computers to make decisions in the real life situations, (for example,

some expert systems help Doctor to Diagnose the diseases based on symptoms).

3. Natural Languages: Programming computers to understand natural human languages.

4. Neural Network: Systems that simulate the intelligence by attempting to reproduce the types of

physical connections that occur in the brains.

5. Robotics: Programming computers to see and hear and react to other sensory stimuli.

Natural-language processing offers the greatest advantage we could simply walk up to a computer and

talk to it. Unfortunately, programming computers to understand natural languages has proved to be

more difficult than originally thought.

There are also voice recognition systems that can convert spoken sounds into written words, but they

do not understand what they are writing; they simply take dictation.

Currently, no computers exhibit full artificial intelligence (that is, are able to simulate human behav-

ior). The greatest advances have occurred in the field of games playing. The best computer chess pro-

grams are now capable of beating humans. In May, 1997, an IBM supercomputer called Deep Blue de-

feated world chess champion Gary Kasparov in a chess match.

Computers and technology of present may have few features of fifth generation computers like – voice

recognition, Expert systems used by Doctors in Diagnoses of patient needs.

1.3 Classification of Computers


Computers are generally classified on the basis of various factors:

1) On the basis of working principals

2) On the basis for Size and data processing

1.3.1 On the basis of working Principals

On the basis of working principals of computers, they can be categorized into Analog, Digital and Hy-

brid computers.

a) Analog Computer

An analog computer (spelt analogue in British English) is a form of computer that uses continuous

physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being

solved. It is different from the digital computer in that it can perform numerous mathematical opera-

tions simultaneously. It is also unique in terms of operation, as it utilizes continuous variables for the

purpose of mathematical computation.

b) Digital Computer

A computer that performs calculations and logical operations with quantities represented as digits,

usually in the binary number system. A digital computer is designed to process data in numerical form;

its circuits perform directly the mathematical operations of addition, subtraction, multiplication,

and division. The numbers operated on by a digital computer are expressed in the binary system; bina-

ry digits, or bits, i.e. 0 and 1.

Binary digits are easily expressed in the computer circuitry by the presence (1) or absence (0) of a cur-

rent or voltage.

A series of eight consecutive bits is called a “byte”; the eight-bit byte permits 256 different “on-off”

combinations.

Each byte can thus represent one of up to 256 alphanumeric characters, and such an arrangement is

called a “single-byte character set” (SBCS);

A digital computer can store the results of its calculations for later use, can compare results with

other data, and on the basis of such comparisons can change the series of operations it performs.


Digital computers are used for reservations systems, scientific investigation, data-processing and word-

processing applications, desktop publishing, electronic games, and many other purposes like business

transaction processing etc.

c) Hybrid Computer (Analog + Digital)

A combination of computers those are capable of inputting and outputting in both digital and ana-

log signals.

Hybrid computer is a digital computer that accepts analog signals, converts them to digital and pro-

cesses them in digital form. This integration is obtained by digital to analog and analog to digital con-

verter.

A hybrid computer capable of real-time solution has been less expensive than any equivalent digital

computer. Hybrid computers have been necessary for successful system development.

An example of a hybrid computer is the computer used in hospitals to measure the heartbeat of the

patient.

Hybrid Machines are generally used in scientific applications or in controlling industrial processes;

they have only a limited usage not suitable for business applications.

1.3.2 On the basis of size and data processing power

Based on the Processing speed, memory capacity and nos. of users computer can handle simultaneous-

ly the computers can be categorized as below: -

(1) Super Computer:

These are the largest, fastest and most expensive computers available, but are not intended for

commercial data processing. They are used to process complex scientific applications such as

weather research, defence, air craft design and computer generated movies.

Super computer were introduced in 1960 as the world’s most advanced computer. As of May 2010,

the Cray Jaguar is the fastest supercomputer in the world.

Sizes/Categorization of Computers

Mini Computer

Micro Computer

Work Station Server

Mainframe Com-

puter

Super Computer


The first super computer was ILLIAC IV made by Burroughs. Other players in the manufacture of

super computer are CRAY, IBM, HITACHI and Sun Microsystems, etc.

The main characteristic that distinguishes the super computer from others is the high degree of par-

allelism, i.e., their ability to perform large number of operations simultaneously.

The processing speed of a super computer can range between 10,000 MIPS (Million instructions per

second) to 1.2 BIPS (Billion instructions per second).

In general, the speed of a supercomputer is measured in "FLOPS" (FLoating Point Operations Per

Second).The FLOPS is a measure of a computer's performance, especially in fields of scientific cal-

culations that make heavy use of floating point calculations, similar to the older, simpler, instruc-

tions per second. "Petascale" supercomputers can process one quadrillion (1015

) (1000 trillion)

FLOPS.

They can support up to 10,000 terminals at a time.

(2) Main Frame Computer: Main frames are less powerful and cheaper than the super computer but

Faster and costlier when compared with Mini computer.

Mainframe can process at several million instructions per second and can support more than 1,000 re-

mote terminals.

Prices of Mainframe computer will range between 1 Crore to 5 Crores depending on the configurations.

Major suppliers of Mainframe computers are IBM, Honey Well, etc.

Mainframe normally used as central computer of big organizations like stock exchange, Banks Head

offices (for Core banking) etc.

Mainframes are also used for applications like Railway reservation or Airline reservation systems.


(3) Mini Computer: Minicomputer performs data processing activities in the way as the mainframe

but on a smaller scale. Data is usually input by means of key board. Minicomputer is small compared

with a mainframe and can be called as scaled-down mainframe, also called as multi user computer as

many persons can connect to the same CPU.

Cost of minicomputer will range from Rs. 5 lacs to Rs. 50 lacs. Most popular mini computer manufac-

turers are IBM; DEC etc.

Programming languages used by minicomputer include – BASIC, PASCAL, COBOL, C and

FORTRAN.

(4)Microcomputers: A Microcomputer is a full-fledged computer system that uses a microprocessor

as its CPU; these are also called personal computer systems.

Microprocessor is a small silicon chip which consists of several integrated circuits used for processing.

Once this microprocessor is combined with other chips like input, output and memory chips on the

mother board then it will take the form of microcomputer.

IBM and Apple are the two most popular players in the microcomputer manufacturing.

The computers that we see in houses, offices are examples of Microcomputers.

Microcomputer in the markets normally contains the below listed: -

CPU : Centrino Duo, Pentium IV, Core 2 Duo, i3, i5, i7

Mother Board : Intel’865

Primary Memory (RAM) : 1 GB to 4 GB, DDR

Secondary Storage : Hard Disk 250 GB or 500 GB, CD/DVD Writer.

Output Devices : 17” CRT or LCD Monitor, Jet Printers

Input Devices : Keyboard, Mouse, and Scanner etc.

Processor : 16 or 32 bit processor.


(5) Work Stations: Between mini computers and microcomputers – in terms of processing power – is

a class of computer called as WORKSTATIONS. Workstation just looks like a personal computer and

is typically used by one person.

Workstation significantly differs in two areas from microcomputers. Workstations are constructed on

different architecture of CPU called RISC (Reduced Instruction Set for Computing) due to which pro-

cessing of instructions will be faster than microcomputers.

Workstation typically runs on UNIX whereas the microcomputer can be run on DOS, UNIX, OS/2 and

Windows. The most prominent manufacturers of Workstation are Sun Microsystems.

6) Server: A Server is a computer system that provides services to other computing systems called cli-

ents over a network. The typical server is a computer system that operates continuously on a network

and waits for requests for services from other computers on the network.

Many servers are dedicated to this role, but some may also be used simultaneously for other purposes,

particularly when the demands placed upon them.

For example, in a small office, a large desktop computer may act as both a desktop workstation for

one person in the office and as a server for all the other computers in the office.

However, servers run software that is often very different from that used on desktop computers and

workstations. Servers primarily use some hardware and software to provide shareable services, exam-

ple – Web Server; Printer Server; Mail Server etc.

1.4 Advantages and Limitations of Computers:

The Computers are very vastly used in present days, by the use of technology of computers the infra-

structure and communication became fast. Life became difficult without computers and technology.

Below are some advantages of computer:

1. Speed: The computers carry out the operations at a very high speed which cannot be imagined or

viewed by the human beings. The smallest unit of time in the human experience is Second, but when it

comes to the computers the operations are measured in milliseconds (10-3

Seconds), microseconds (10-6

Seconds), nanoseconds (10-9

Seconds) and picoseconds (10-12

Seconds).


The computer generates signals during the operation process therefore the speed of computer is usually

measure in megahertz (MHz) or gega hertz (GHz). It means million cycles units of frequency per se-

cond. Different computers have different speed.

2. Accuracy & Precision: Accuracy is an issue pertaining to the quality of data and number of errors

contained in the data set. The accuracy is important to rely and act upon on any information; computers

even processing at high speed will deliver the results with accuracy. Level of accuracy required varies

from application to application basing on the rounding of fraction values.

Example - commercial data processing accuracy of the values can be up to 2 to 4 decimal points, in

case of scientific applications the accuracy of the value may be required up to 12 to 15 or even more

decimal points.

3. Reliability: Now a days the computers down time came down drastically, their up time can be said

at 99% i.e. computer has almost nil down time. Down time means the time during which computers are

not available for processing. Even in case of disasters or emergency system crashes many plans are in

place to run the systems from the backup systems which may be located at different place.

The IEEE defines it as "the ability of a system or component to perform its required functions

under stated conditions for a specified period of time."

4. Memory Capability/Storage: The data which is processed for the commercial purpose or any sci-

entific purpose needs to be stored and should be able to access or retrieve when ever required with less

effort. Thus Memory is more important, Computer systems have total and instant recall of data and an

almost unlimited capacity to store these data.

5. Communication: With the advanced technology in the networking the computers will be able to

transfer the information from one place to another immediately. Example – When we send a mail, it

reaches to the destination in few seconds.

Computers in the combination of the networks made possible of business style – ‘Any Time Any

Where’ eg- ATM Machines, where we can draw cash, check balance etc.

6. Automation: A computer can automatically perform operations without interfering with the user

during the operations. It controls automatically different devices attached with the computer. It exe-

cutes automatically the program instructions one by one.

7. Versatility: Versatile means flexible. Modern computer can perform different kind of tasks done by

one or simultaneously. It is the most important feature of computer. At one moment we can play games

on computer, the next moment we can compose and send emails etc. In colleges and universities com-

puters are used to deliver lectures to the students. The talent of computer is dependent on the software.

8. Consistency: People often have difficulty to repeat their instructions again and again. For example,

a lecturer feels difficulty to repeat a same lecture in a class room again and again. Computer can repeat


actions consistently (again and again) without loosing its concentration. A computer will carry out the

activity with the same way every time.

Limitations: Despite of all the above advantages computers also has their own limitations or disad-

vantages as listed below -

1. Programming: Any computer to perform it requires instructions for what to do, how to do and

when to do. These instructions for a computer can be called as programmes.

Thus if the program is correct with no errors then the actions performed by the computer will be accu-

rate and reliable.

2. No Intelligence: Although computers are faster, more diligent, accurate and versatile than human

beings, it cannot replace them. Unlike human beings, computers do not have any intelligence. Its per-

formance is depends on instructions given to it. It cannot carry any task at its own.

3. No decision making power : Computer cannot make any decisions nor can it render any help to

solve a problem at its own like that if we plays chess with computer, the computer can take only those

steps which is entered by the programmer. It cannot move at its own.

4. Curtail human Capabilities: Although computers are great help to human beings. It is commonly

felt that we people have become so dependent on calculator that we cannot make very simple calcula-

tion without calculator. Sometimes, find it difficult to instantly speak out even those telephone numbers

which they use every now and then as they have got the habit of using them by retrieving the storage.

Further, excessive use of computers is causing various type of health injuries such as cervical and back

pain, pain in eye, headache.

5. Application logic must be understood: computer may not be helpful to people in areas where sub-

jective evaluations are important. For example, it may not be able to tell a sales manager if a new prod-

uct will be successful. But the computer can tell the manager how the product will fare under assumed

price, cost, and sales volume conditions. These assumed values could be fed into the computer.

6. Data input: The computers will perform all the operation using the programs on the data input;

when the data is not reliable and accurate even though the program is correct the out put will be wrong.

In computer terms it is popularly known as GIGO (Garbage In and Garbage Out). The output of the

programs will be based on the input data and the accuracy of the programs.

7. Skilled Manpower: The availability of the skilled manpower is also one limitation, now days the

availability is increasing.

Conclusion: - Despite of the above few limitations the computers have become very popular and been

part of human life, where it is very difficult to imagine the life without computer.


1.5 Basic Computer Architecture

1.5.1 Basic computer functions

In Computer System, different parts of a computer are organized in such a way that, it helps to per-

form various operations to complete the given specific task. Widely computers are used to perform

arithmetic calculations. However, now-a-days computer is used for many other purposes. A com-

puter as shown in figure performs basically five major operations or functions irrespective of their

size and make. These are

1. It accepts data or instructions by way of input,

2. It stores data,

3. It can process data as required by the user,

4. It gives results in the form of output, and

5. It controls all operations inside a computer

1. Input: It is the process of entering data and programs into the computer system. Input is further pro-

cessed to produce the required results. Input will be received in a prescribed format.

2. Storage: The process of saving data and instructions permanently is known as storage. The primary

storage of the computer system is designed to supply data and inputs to CPU so to meet its speed of

processing, the storage is not permanent. The Secondary storage is used to store the data permanently.

The storage unit performs the following major functions:

All data and instructions are stored here before and after processing.

Intermediate results of processing are also stored here.

3. Processing: The task of performing operations like arithmetic and logical operations is called pro-

cessing. The Central Processing Unit (CPU) takes data and instructions from the storage unit and

makes all calculations based on the instructions given and it is then sent back to the storage unit.

4. Output: This is the process of producing results from the computer to users. The output produced

by the computer can also be kept inside the computer for further usage or can be directly sent out.


5. Control: The manner how instructions are executed and the above operations are performed. Con-

trolling of all operations like input, processing and output are performed by control unit. It takes care of

step by step processing of all operations inside the computer.

1.5.2 Component of Computer Systems – CPU

We will now briefly discuss each of the above components

Computer needs two things to function properly, Hardware and Software.

Hardware consists of several physical components like Key Board, CPU, Monitors, Mouse and other

peripheral devices CD/DVD Drive, modems, Printers etc.

Software consists of programs which are further classified as System programs (e.g. Operating System

like Windows, DOS) Application programs (MS-Word, MS-Excel, Tally etc.)

Computer Hardware is classified as – CPU and Peripheral Devices.

1.5.2.1 Central Processing Unit (CPU):

The Central Processing Unit (CPU).also known as the processor is the heart, soul and brain of the com-

puter. In a microcomputer, the entire CPU is contained on a tiny chip called a microprocessor

Currently the Pentium chip or processor, made by Intel, is the most common CPU, this is the most im-

portant part on the mother board (a platform which allows all the devices stay connected and flow of

data among them).


Every CPU has at least two basic parts, Control Unit and Arithmetic Logical Unit which co ordinates

with each other.

1. Control Unit:

All the computer’s resources are managed from the control unit. The Control unit function is to co or-

dinate all the activities of the computer like controlling the inputs and outputs.

Any instruction which involves movement of data from one device to another like from primary

memory to printer or Storage device (Hard Disk) etc is executed by control unit and if any instruction

contains arithmetic and logical operation on data then it is transferred to ALU.

A CPU contains in built instructions for carrying out various types of operation. Each instruction or in-

struction set is expressed in microcode-a series of basic directions that tell the ALU how to execute.

To execute any instruction, the instruction is first of all reaches to Control unit, which created the cor-

responding microcode and passes it to ALU, where the actual execution of the instruction takes place.

Usually, when a new CPU is developed, the instruction set has all the same commands as its predeces-

sor plus some new ones. Therefore, more the instructions in the instruction set of CPU more advance is

the CPU.


2. Arithmetic Logic Unit: As said earlier every instruction to the computer first reaches the control

unit and if it contains any Arithmetic or Logic operation the respective microcode is passed to the ALU

(Second component of CPU).

ALU includes a group of circuits and registers, Circuits to process data and registers which are high

speed storage used to hold the data currently being processed, (this is a temporary memory).

ALU can perform two types of operations, Arithmetic operations like – addition, subtraction, multipli-

cations and divisions. Logical operations like – comparison between two numbers or text.

1.5.2.2 Various features of Central Processing Unit (CPU): Over a period of time, the processor has

evolved from slow 286s or 386s running at speeds as low as 20 MHz to present day Pentium III and IV

running at a whooping 3 GHz (3000 MHz i.e. 3,000,000,000 cycles) Now we take a closer look at the

various features that the Central Processing Unit of a PC offers.

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Let’s have a look at the picture of CPU cabinet

1. Clock Speed: The clock speed is the speed at which the processor executes instructions. Clock

speed is measured in megahertz (MHz).which is a million cycles per second, therefore processor Penti-

um IV with 3 GHz (3000 MHz) executes 3000 million instructions per second.

Higher the clock’s speed, the faster the processor, the better the system performance. Also, some mi-

croprocessors are super scalar, which means that they can execute more than one instruction per clock

cycle.

2. Cache Memory: Processors incorporate their own internal cache memory. The cache acts as tempo-

rary memory and boosts processing power significantly. The cache that comes with the processor is

called Level One (L1) cache. This cache runs at the processor’s clock speeds, and therefore is very fast.

The L1 cache is divided into 2 sections. One for data, the other for instructions. Generally, more the L1

cache, faster the processor.

Additionally, PCs also include a much slower secondary, or Level Two (L2) cache. This cache resides

on the motherboard and delivers slower performance when compared with the L1 cache. To overcome

this limitation, newer chips (Pentium II and Pentium III) house the L2 cache in a cartridge along with

the CPU.

Working of Cache Memory:

Cache

Memory:

Internal

Memory of

CPU

CPU’s Slot

& Socket:

Holder of

CPU on

Mother Board

MMX (Multimedia

Extension):

Instruction set in

CPU which process

Audio & Video data

Density: No. Of Tran-

sistors in

CPU

Clock Speed:

Measurement

of Instruction

processing

speed of CPU


It is a memory of main processor. Whatever data we send to computer first of all it reaches to main

memory (RAM). From this main memory it goes to processor (CPU) for processing and it comes to

main memory once processing is finished.

As the processor is much faster than the main memory, lot of time is consumed in transferring the data

back and forth between main memory and processor.

In order to reduce the time consumed in transferring of data between main memory and Processor, we

use cache memory which is inside the processor itself and much faster than RAM.

As shown in the memory diagram with cache memory the CPU will be communicating with high speed

cache memory in place of normal RAM therefore, the effective processing speed of computer would

increase.

3. Slot: A CPU socket or CPU slot is an electrical component that is attached to a printed circuit board

(PCB) and is designed to house a microprocessor. It is a special type of integrated circuit socket de-

signed for very high pin counts.

A CPU socket provides many functions, including providing a physical structure to support the CPU,

providing support for a heat sink, facilitating replacement (as well as reducing cost) and most im-

portantly forming an electrical interface both with the CPU and the PCB.

Different processors use different sockets or slots to fit onto the motherboard. Based on the type of

processors, there are various types of slots.

4. Density: A CPU is made up of millions of small transistors. A CPU performs all the calculation and

manipulation operations by synchronising between the transistors. Therefore, the shorter the distance

between two transistors on a CPU, the faster the performance. Older CPUs had a distance of one mi-

cron between the transistors. But, newer CPUs have a distance as small as 0.35 micron between two

transistors, delivering faster performance.

5. MMX: MMX stands for Multimedia extensions a set of instructions built into the CPU, specifically

intended for improving the performance of multimedia or graphic applications like Games, Videos and

Audio applications.

The processors which have the inbuilt instructions for multimedia data processing are called as proces-

sors with MMX features. MMX is now normal or default feature of all the CPU.


1.6 Components of Mother Board: The motherboard or the system board is the main circuit board on

the computer. It acts as a direct channel for the various components to interact and communicate with

each other. There are various types of motherboards available (depending on the processors that are

used)

Above is a snapshot of mother board and its components

Following are the main components of mother board:

1.6.1 Processor slot: The processor slot houses the processor. It is rectangular connector into which

the processor is mounted vertically. It also refers more specifically to a square-shaped connector with

many small connectors into which the processor is directly inserted.

1. BIOS: BIOS stands for Basic Input Output System, a small chip on the motherboard that loads the

hardware settings required to load various devices like keyboards, monitors, or disk drives. BIOS is al-

so known as ROM BIOS because it is ROM chip (IC) which contain system software known as Basic

input output system which used for initial operation of computer.

BIOS contain permanent instructions or programs also known as start up programs used in booting or

starting of computer.


2. CMOS (Complimentary Metal Oxide Semiconductor): The PC uses the CMOS memory to store

the date, time and system setup parameters.

These parameters are loaded every time the computer is started. A small Lithium Ion battery located on

the motherboard powers the CMOS as well as the BIOS.

3. Power supply connectors: The power supply connectors allow the user to connect the power sup-

ply unit to the motherboard and provide power for the functioning of the various devices or compo-

nents like CD/DVD writer, Hard Disk, etc.

16.2 Expansion Slots and Boards: PCs are designed so that users can adapt, or configure the ma-

chines to their own particular needs. PC motherboards have two or more expansion slots. These slots

are used normally for I/O devices like graphical adopter card on which the visual display unit is at-

tached. Similarly we can put the Modem card to use the internal modem. These expansion slots are also

used for connecting CD/DVD drive, external Hard disk or Pen drives etc.

In general these are known as expansion slots as these slots helps to expand the capability of the com-

puter by attaching more devices or using computer with added capability like TV tuner card is used in

expansion slot to use the computer as TV.


Picture of Expansion Slots

Some of the Slots are briefly discussed below:

1. SIMM/DIMM slots: SIMM stands for Single Inline Memory Modules, while DIMM stands for

Dual Inline Memory Module. SIMM/DIMM slots are used to house RAM modules. Now a day almost

all the computers are using DIMM as the SIMM is outdated technology.

2. PCI slots: Now a day almost all the expansion slots provided on mother board are of PCI types.

The PCI (Peripheral Component Interface) slots are used for connecting PCI-based devices like

graphics accelerator cards, sound cards, internal modems or SCSI cards.

3. AGP slot: All Celeron and Pentium-III/P-IV motherboards come with an AGP (Accelerated

Graphics Port) slot. AGP is a dedicated slot meant to provide faster access to AGP-based graphic ac-

celerator cards, thus enhancing the visual experience for the user. AGP card normally keeps a dedicat-

ed processor for graphic processing and video RAM for storing graphical data for a quality output of

graphical data.

4. ISA: Industry Standard Architecture was a computer bus standard for IBM compatible computers.

This is most ancient type of expansion slot ever used in the computer system. The ISA enables control-

lers connect directly to the bus to communicate directly with the other peripherals without going

through the processor. However, the ISA bus only allows hardware to address the first 16 megabytes

of RAM.

5. SCSI: It is a device interface that is used to solve the problem of a finite and possibly insufficient

number of expansion slots. It is called small computer system interface (SCSI pronounced .scuzzy.) In-

stead of plugging interface cards into the computers bus via the expansion slots, SCSI can be inserted

in one expansion slot and we can extend that slot to outside the computer by way of a cable. In other


words, SCSI is like an extension cord for computer bus. The current standard is SCSI - 3, which allows

upto 7 devices to be chained on a single SCSI port. Now-a-days many devices support the SCSI inter-

face. Fast, high-speed hard disk drives often have SCSI interfaces, so do scanners, tape drives and op-

tical storage devices.

1.6.3 Cards:

Cards are components added to computers to increase their capability or to have additional functionali-

ties. When adding a peripheral device one should ensure that the computer has a suitable slot.

Sound cards allow computers to produce sound like music and voice. The older sound cards were 8 bit

then 16 bit then 32 bit.

Colour cards allow computers to produce colour. The first colour cards were 2 bit which produced 4

colours [CGA]. Next came 4 bit allowing for 16 [EGA and VGA ] colours Then came 16 bit allowing

for 1064 colours and then 24 bit which allows for almost 17 million colours and now 32 bit is standard

allowing monitors to display almost a billion separate colours.

Video cards allow computers to display video and animation. Some video cards allow computers to

display television as well as capture frames from video. A video card with a digital video camera al-

lows computer users to produce live video (Web Cam). A high speed or network connection is needed

for effective video transmission.

Many video cards offer added functions, such as accelerated rendering of 3D scenes and 2D graphics,

video capture, TV tuner adapter, MPEG-2/MPEG-4 decoding,

Network cards allow computers to connect together to communicate with each other. Network cards

have connections for cable, thin wire or wireless networks.

http://en.wikipedia.org/wiki/File:Scsi-1_gehaeuse.jpg

http://en.wikipedia.org/wiki/File:Scsi-1_gehaeuse.jpg

http://en.wikipedia.org/wiki/File:SCSI_25-50.jpg

http://en.wikipedia.org/wiki/File:SCSI_25-50.jpg


16.4 Ports & Connectors:

Ports and connectors let the user connect external devices like printers, keyboards, monitors or scan-

ners and let them interface with the PC (Personal Computer). The physical interfaces for the ports and

connectors are located on the outside of CPU cabinet but they are directly or indirectly (using a con-

nector card) connected to the motherboard. There are various types of ports or connectors, each

providing different data transfer speeds to connect various external peripherals.

Parallel ports: Parallel ports are used to connect external input/output devices like scanners or print-

ers. Parallel ports facilitate the parallel transmission of data, usually one byte (8 bits) at a time. Paral-

lel ports use 25 pin RS- 232C.

Com/Serial ports: They are used for connecting communication devices like modems or other serial

devices like mouse, Keyboard. There are two varieties of Com ports the 9-pin ports and 25-pin ports.

Serial Ports facilitate the serial transmission of data, i.e. one bit at a time.

IDE drive connector: IDE devices like CD-ROM drives or hard disk drives are connected to the

motherboard through the IDE connector.

http://en.wikipedia.org/wiki/File:Parallel_computer_printer_port.jpg

http://en.wikipedia.org/wiki/File:Parallel_computer_printer_port.jpg

http://en.wikipedia.org/wiki/File:Serial_port.jpg

http://en.wikipedia.org/wiki/File:Serial_port.jpg


Floppy drive connector: The floppy drive connectors are used for connecting the floppy drive to the

motherboard, to facilitate data exchange. Now a days floppy drives are hardly used by any personal

computers.

USB Port or connectors: USB stands for Universal Serial Bus. This is latest and most popular port

technology. These ports provide the user with higher data transfer speeds for different USB devices

like keyboards, mouse, scanners or digital cameras.

PS/2 Connectors: PS/2 stands for Personal System/2. PS/2 connectors are used to connect PS/2 based

input devices like PS/2 keyboards or mouse.

Monitor Ports: The monitor port is used to connect monitor with the system. These are called as VGA

(Video graphic Array) connector

Power Connectors: These are used to connect the power chord from external power supply source,

from which the internal power supply connectors get the power to the mother board and other devices.

http://en.wikipedia.org/wiki/File:USB_Connector.jpg

http://en.wikipedia.org/wiki/File:USB_Connector.jpg

http://en.wikipedia.org/wiki/File:Ps-2-ports.jpg

http://en.wikipedia.org/wiki/File:Ps-2-ports.jpg

http://en.wikipedia.org/wiki/File:VGA_port.jpg

http://en.wikipedia.org/wiki/File:VGA_port.jpg


In addition to the common components that are found on the motherboard, newer motherboards also

come with integrated graphics accelerator cards or sound cards-there is no need to install a separate

card to get the work done.

View of Ports & Connectors

1.6.5 The Bus:

The maze of circuits etched on the motherboard forms the bus of the PC. A bus acts as the system’s

expressway -it transmits data between the various components on the motherboard.

Theoretically, a bus is a collection of wires through which data is transmitted between the various

components of a PC. A bus connects the various components of the PC with the CPU and the main

memory (RAM) logically, a bus consists of two parts, an address bus and a data bus.

The Data Bus: The Data Bus is an electrical path that connects the CPU, memory, and the other hard-

ware devices on the motherboard. Actually, the bus is a group of parallel wires. Each wire can transfer

one bit at a time, an 8-bit bus can move eight bits at a time, which is a full byte. A 16-bit ISA (Industry

standard Architecture) bus can transfer two bytes, later 32-bit MCA (Micro channel Architecture) and

32 bit EISA (Extended Industry standard Architecture) bus was introduced these can transfer 4 bytes at

a time, present days 64 bits bus called as PCI (Peripheral component Interconnect) Bus is used.

PC buses are designed to match the capabilities of the devices attached to them. When CPUs could

send and receive only one byte of data at a time, there was no point in connecting them to a bus that

http://en.wikipedia.org/wiki/File:IEC60320_C14.jpg





could move more data. As microprocessor technology improved, however, chips were built that could

send and receive more data at once, and improved bus designs created wider paths through which the

data could flow.

The Address Bus: The second bus that is found in every microcomputer is the address bus. The ad-

dress bus is a set of wires similar to the data bus that connects the CPU and RAM and carries the

memory addresses.

The computer power is not only known for its speed, but also for its storage capacity. Computer

memory holding capacity is determined based on the size of Address bus. More width of an address

bus more it has the memory capacity.

Over the year the size of the address bus has been increased to 32 bits from 20 bits, a 32 bit address bus

system can address 4 GB of memory capacity.

Control bus :( or command bus) transports orders and synchronize signals coming from the control

unit and traveling to all other hardware components. It is a bidirectional bus, as it also transmits re-

sponse signals from the hardware. A control bus is a computer bus, used by CPUs for communicating

with other devices within the computer.

It is used to transmit a variety of individual signals (read, write, interrupt, acknowledge, and so forth)

necessary to control and coordinate the operations of the computer. The individual signals transmitted

over the control bus and their functions are covered in the appropriate functional area description.

1.7 Storage Devices

The CPU requires the basic instructions needed to operate the computer, but it does not have the capa-

bility to store programs (Instructions) or large sets of data permanently. Just like human brain which

stores all the data, computer needs blocks of space where it can store the instructions that help in pro-

cessing arithmetical and logical operations. This area is called memory or storage.


1.7.1 Types of Storage Devices:

Various forms of storage devices are invented each with an individual purpose shown above

1. Primary Storage: Primary storage is either connected directly or a part of the CPU, this must be

present for CPU to function properly. As shown in the figure the primary storage consists below parts:

Process Registers are internal memories of CPU. These are the fastest memories than all forms of

computer storage. Registers holds the information that the Arithmetic and Logic units need to carry out

the current instruction.

Main Memory Contains the programs that are currently being run and the data on which the programs

are executed. The ALU can very quickly transfer information between the process register and the loca-

tion in main memory known as memory addresses. In present computer the RAM (Random Access

Memory) is used as main memory which is directly connected to CPU via “Address bus” and “Data

bus”.

Main Memory


Cache Memory is a special type of internal memory used by CPU for improving the performance and

output. This memory is used to hold those data and instructions which are frequently used by CPU.

This memory is used in limited capacity than RAM.

2. Secondary, tertiary and offline storage: These storage devices are used for Mass storage of data.

These storages are also known as permanent storage devices, where as primary storage is used to hold

the data temporarily till the processing completed.

Secondary storage requires the computer to use its input/output channels to access the information and

used for long-term storage of persistent information. Hard disks are the most popular secondary storage

devices. Time taken to access the data from Hard disks are much less than the time taken to access data

from Magnetic tapes, rotating devices like CD or DVD’s.

Tertiary storage is removable storage devices like CD’s and DVD’s but the process of removing and

inserting the devices is carried out by Robotic arms automatically as per the operating systems instruc-

tions. These types of storages are not seen in the personal computers.

Offline storage is a system where the storage medium can be easily removed and inserted manually.

Offline storage can be used for data transfer, Back up or Archival purpose. In modern computers the

offline storages are – CD’s DVD’s and Flash Memory (Pen Drives, Memory cards etc.) In past the of-

fline storages are Magnetic tapes.

Robotic storage is a new type of storage method used for backups, and for high capacity archives in

imaging, medical, and video industries. Robotic-access storage devices may have a number of slots,

each holding individual media, and usually one or more picking robots that traverse the slots and load

media to built-in drives. The arrangement of the slots and picking devices affects performance.

3. Network Storage: Network storage allows to centralise the information management in an organi-

sation, and to reduce duplication of information. Network storage includes,

Direct Attached Storage (DAS) refers to a network storage system on which data is saved to the serv-

er computer's internal hard drive.

The network workstations access the server to connect to the storage. These files are saved directly on-

to the computer's disk space and can be readily pulled up at any time. This is the most commonly used

means of network storage.

The disadvantages of DAS include its inability to share data or unused resources with other servers.

Network Attached Storage (NAS) is a type of network storage system that saves data onto another

computer system attached to a group of computers through a network, or onto a special server attached

to the network.

A NAS device is typically a stand-alone, high performance, single purpose system or component.


It serves specific storage needs with its own operating system and integrated hardware and software.

NAS devices are well suited to serve heterogeneous networks. The advantages of NAS over other

methods of storage are performance and connectivity.

Storage Area Network (SAN) is an architecture to attach remote computer data storage devices (such

as disk arrays, tape libraries, and optical jukeboxes) to servers so the devices appear as locally attached

to the operating system.

A SAN typically has its own network of storage devices that are generally not accessible through the

regular network by regular devices. SAN reduces data traffic and improves data access by using Fiber

connections.

1.7.2 Characteristics of Storage: The different storages like primary, secondary, tertiary and offline

have the below characteristics:

1. Volatility of information

Volatile memory requires the constant power supply to maintain the information; these are used as

mainly for primary storage. Once power is off the information stored in these will be erased automati-

cally e.g. RAM.

Non-Volatile memory will retain the information that is stored even if power supply is off. It is suita-

ble for long term and permanent storages. Therefore these are used for Secondary, Tertiary and offline

storages. E.g. – Hard disk, DVD’s Pen drives.

Dynamic memory is volatile memory which also requires that stored information is

Periodically refreshed, or read and rewritten without modifications.

2. Ability to access non-contiguous information

Random Access means any location in storage can be accessed at any moment in the same amount of

time. This provides fast access to the data stored.

Sequential Access means accessing a piece of information sequentially i.e. one by one from the posi-

tion of last accessed information.

3. Ability to change or delete information

Read/Write storage or Mutable storage allows information to be over written, modify, delete or re-

trieve the required information at any time, e.g. Hard Disk. Modern computers use these storages as

Secondary Storage.


Read only storage retains information stored at the time of manufacture and Write Once Memory

(WROM) allows to write information only once at any point of time e.g. – CD.

These are called Immutable Storage, mainly used for Tertiary storage and Offline back up storage.

The information stored in these cannot be changed.

Slow Write, fast read storage is read/write storage which allows information to overwritten multiple

times, but with the write operation being much slower than the read operation, e.g. Re-writeable

CD/DVD

4. Addressability of information

Location Address Storage: In this each individual character of information is given separate address

e.g. RAM

File Address Storage: In this information is divided into files and file is provided an address which is

a human readable. The underlying device still uses location address system but operating system will

provide the file abstraction to make the operation more understandable

Content Address Storage: These are also implemented with the use of some software to address a

particular content or field like you look in your mobile for – Dialed numbers, Missed calls, Received

calls etc.

5. Capacity and Performance

Storage capacity is the total size of the information that a storage device or medium can hold. It is

measured as Megabytes (MB) or Gigabytes (GB).

Storage Density defines the compactness of stored information. It is measured as megabytes per

square inch or gigabytes per square inch.

Latency is the time taken to access the information from the storage device as we know Hard disk

takes less time to access the information than the Floppy. It is measured in millisecond, microsecond or

nanosecond etc.

Throughput is the rate at which the information can read from or written to storage devices. It is

measured in the MB/sec GB/sec.

1.7.3 Primary Storage

Following are various types of system memories in the computer system. These are also known as on

board Memories i.e. memories on some circuit board.


1. Semiconductor Memory: Semiconductor memories are in the form of thin chip known as Integrat-

ed Circuit (IC). These memories are made with semiconductor material known as Silicon. There are

various technologies of semi-conductor memories, faster and more expensive bipolar semiconductors

are often used in Arithmetic Logic Units and high speed buffer storage sections of the CPU, while

slower and less expensive metal-oxide semi-conductors (MOS) are used in primary memory.

1) These memories are made with a semiconductor material known as silicon in the form of IC (chip).

2) These silicon chips consists of large no of transistors (Storage cells) that can hold the large capacity

of data

3) These memories are very fast in operation (no moving or mechanical part is used, as in Floppy or

Hard disk) and consume low power.

The ICs can be scaled according to the capacity of the chip used in storing the data in computer system:

SSI (small-scale integration): Up to 100 electronic components per chip.

MSI (medium-scale integration): From 100 to 3,000 electronic components per chip.

LSI (large-scale integration): From 3,000 to 100,000 electronic components per chip.

VLSI (very large-scale integration): From 100,000 to 1,000,000 electronic components per chip.

ULSI (ultra large-scale integration): More than 1 million electronic components per chip.

2. RAM (Random Access Memory):

Primary Storage

Semiconductor

Memory

RAM ROM Bubble

Memory

Flash

Memory

Video

RAM

Dynamic

RAM

Static

RAM

PROM EPROM EEPROM


1) The RAM is high speed semi-conductor memory, it is synonym with computer main memory i.e. all

the computers main memories or primary memories are known as RAM.

2) RAM is that memory in computer, that holds the instructions and data which are currently under

execution.

3) RAM is a volatile memory; the information in RAM will be lost once the power is switch off.

4) Data in the RAM can be accessed or insert directly, hence this memory is called as Random Access

Memory.

RAM can be of two types – Static RAM and Dynamic RAM, discussed below:

The Static RAM retains the stored data as long as the power remains on, whereas with dynamic RAM,

the stored information disappears after a few milliseconds have elapsed, even when power is on.

The data must, therefore be repeatedly refreshed before it disappears. The power consumption of a dy-

namic RAM is less than that of a static RAM, which has the advantage of making a higher degree of

integration possible.

The computer does the refreshing process itself, taking time out from other chores every few millisec-

onds. It will read all the RAM memory positions while they are still readable and put appropriate new

charge on each capacitor. Some dynamic RAM memory circuits include built-in refresh circuits to re-

lieve the computer.

Presently used is DDR SDRAM (Double Data Rate Synchronous DRAM) used for RAM chips and

SRAM are used for high speed but less storage capacity cache memory units.

Other Types of SRAM – Asynchronous SRAM; Synchronous SRAM; Pipeline Burst SRAM.

3. ROM (Read Only Memory):

Another type of computer memory is the Read Only Memory it is used for the Micro programs. The

name implies that the data stored in this can only be read and cannot be altered by any regular pro-

grams. The information is stored permanently at the time of manufacture. These are used for storing


permanent instructions which computer may be executing frequently. One set of instruction found in

ROM is ROM- BIOS which stands for Read Only Memory Basic Input Output Services.

Types of ROM,

PROM: Programmable Read Only Memory is a non-volatile memory which allows the user to pro-

gram the chip with a PROM write. The chip can be programmed once, thereafter, it cannot be altered.

EPROM: EPROM stands for Erasable Programmable Read Only Memory. EPROM chips can be elec-

trically programmed. Unlike ROM and PROM chips, EPROM chips can be erased and reprogrammed.

Erasure is performed by exposing the chip to Ultra-violet light.

EEPROM: Electrically Erasable Programmable Read Only Memory is EPROM. However, the data

can be erased by applying electrical charges.

Rom is mainly used for storing system software and set of start up instructions for computer and some

micro program to control the computer hardware and these start up instructions and micro program are

known as BIOS.

4. Bubble Memory: This Bubble memory is composed of small magnetic domains (bubbles) formed

on a thin single-crystal film of synthetic garnet. These bubbles which are actually magnetically

charged cylinders which are thousandth of centimeter in size, can be moved across the garnet film by

electric charges. The presence or absence of a bubble can be used to indicate whether a bit is “on” or

“off”. The bubble memory is non volatile i.e. data will reside even power is turned off. Therefore, this

memory can be used for auxiliary storage. Since it is small, lightweight, and does not use very much

power, bubble memory is finding a great deal of use as an auxiliary storage in portable computers.

5. Flash memory: Flash memory chips are one of the latest storage devices. These chips, a form of

static RAM (SRAM) chips, store data much like those used in the computer’s primary storage. How-

ever, the data stays recorded even when the power is turned off flash memory is non-volatile. Since

flash memory devices have no moving parts, and are therefore very fast, they may eventually replace

slower, mechanical hard disk drives.


Flash memory is small in size portable memory, can easily carry in pocket, these are being used as aux-

iliary memory in small size PDA (Personal Digital Assistant), Palm Top computer and Digital Camera

etc.

6. Video RAM: This is a memory used for quality graphic display. It is normally part of AGP (Accel-

erated Graphic Processor Card) and help in accelerating the display of graphics, special effects on the

screen. It does this by using two .ports,. one connected to the CPU and the other to the screen. Data

flows in one port and out the other very smoothly.

1.8 Secondary Storage:

Mainly there are two types of memory in computers. One is known as Primary memory and other is

secondary memory or auxiliary storage. Primary storage is built into the CPU whereas secondary stor-

age or auxiliary storage is usually housed in a separate unit or units. Primary storage is very fast-its

contents can be accessed in millionth or billionths of a second. But primary storage has a limited capac-

ity and cannot store data permanently. In order to overcome these problems of primary memory com-

puters always has a secondary memory to store data permanently. Secondary storage has an almost in-

finite capacity measured in millions and billions of bytes.

Primarily there are two types of auxiliary storage although there are Magneto – Optical and semicon-

ductor memories also which are used as auxiliary storage devices.

1.8.1 Floppy Diskettes:

In the early 1970.s IBM introduced a new medium for storing data. This medium consisted of a circular

piece of thin plastic material, approximately eight inches in diameter that was coated with an oxide ma-

terial. The circular piece of plastic, called a disk, is enclosed in a square protective jacket with a cut out

(Read/Write Slot) so that the magnetic surface is exposed for data storage and retrieval.

Diskettes are available in a number of different sizes. The original diskette was of the size of 8 inches.

During the 1980, most PCs used 5.25-inch diskettes. Today, the 3.5- inch diskette has largely replaced

its 5.25-inch cousin. The size refers to the diameter of the disk, not to the capacity. As mentioned

above surface of diskette are coated with millions of small iron particles (Oxides) to store the data.

Each of these particle acts as a magnet. When read/write head of floppy drive passes over these mag-

nets it generates magnetic field in these magnet to store data.


5.25” Floppy 3.5” Floppy

Floppy Drive

Floppy diskette when inserted in the floppy drive will start doing the circular motion. Normal rotational

speed of floppy is 300 rotations per minute. Read/Write head of drive can do the linear movement only.

1.8.1.1 How Data is stored or organized on Floppy Disk:

When the new diskettes (or a new hard drive) are purchased, the disks inside are nothing more than

simple, coated disks encased in plastic. Before the computer can use them to store data, they must be

magnetically mapped so that the computer can go directly to a specific point on the diskette without

searching through data.

The process of mapping a diskette is called formatting or initializing. Today, many diskettes come

preformatted for either PCs or Macs. The first thing a disk drive does when formatting a disk is to cre-

ate a set of magnetic concentric circles called tracks.


Tracks & Sectors

Magnetic material of disk which stores data is divided into concentric circles known as tracks. The

Tracks are further divided into sectors. Each sector has unique number on the disk, which help comput-

er to access or store data on floppy disk. Sectors are used ultimately to store or refer data on diskette.

Now a days 3.5 inch floppy is double sided (means both the sides can store the data), with 80 tracks per

side and 18 sectors per track with 512 bytes on every sector.

The Storage capacity of the diskette is dependent on the following three factors.

1. The number of sides on the diskette i.e. single sided or double sided now a days only double sided

diskette (which can store the data on both sides of diskette) are available in market

2. Recording density: Recording density refer to number of bits that can be stored on one inch of in-

ner most tracks known as bpi (bits per inch). Diskette can be single density (2768 bits per inch), dou-

ble density (5876 bits per inch) or high density (excess of 10000 bits per inch) now a day only high

density floppy diskettes are available in the market.


3. Number of Tracks: Number of tracks depends on the drive but now a days only 80 tack per side is

available in the market.

1.8.1.2 How operating system read data or Floppy is used for reading and writing purpose?

A computer’s operating system is able to locate data on a disk (diskette or hard drive) because each track and

sector is labeled, and the location of all data is kept in a special log on the disk. The labeling of tracks and sec-

tors is called performing a logical or soft format. A commonly used logical format performed by DOS or Win-

dows creates these four disk areas:

1. The boot record

2. The file-allocation table (FAT)

3. The root folder or directory

4. The data area

1. The boot record: It is a small program that runs when the computer is started. This program determines

whether the disk has the basic components of DOS or Windows that are necessary to run the operating system

successfully. If it determines that the required files are present and the disk has a valid format, it transfers con-

trol to one of the operating system programs that continues the process of starting up. This process is called

booting because the boot program makes the computer .pull itself up by its bootstraps.

Boot record also keeps some other information like no. of bytes per sector and sectors per track etc., which help

the operating system to access the data area of disk.

2. File Allocation table (FAT): This is the most important area for keeping the data on the floppy. This area

keeps the address information for all the files stored on the floppy. Whenever a new file is stored by operating

system on the floppy its address information is placed in the FAT. So when operating system wants to access

any file it takes its address information from FAT and accordingly access the file. FAT area also provides in-

formation to operating system regarding the available free area on disk for storage, which ultimately helps OS

in efficient storage of data.

A user normally cannot access FAT area to check the available free tracks and sectors or files stored on the

disk. But user can use one more tool known as folder or directory to check the stored files and available free

space on the disk. A folder keeps the files and other folders in a hierarchical form for providing a tree view of

stored data and files.

3. Root Folder: As we mentioned above in the FAT that user can view the stored data files and available free

space using a tool called folder or directory, which organize the files and other folders in a hierarchical form.

The top folder of this hierarchical arrangement is called as Root Folder. E.g. – C:, A: for Floppy disk.

4. Data Area: The part of the disk that remains free after the boot sector, FAT, and root folder have been cre-

ated is called the data area because that is where the data files (or program files) are actually stored. This is

the largest area on the disk.


1.8.1.3 Care required in using and storing a diskette: On receiving a new diskette, it should be inspected for

sign of obvious damage. The surface of the diskette should not be touched with hand or some sharp object.

Write-protect precaution should be observed by peeling off or sticking on (as applicable) the aluminum square

on the notch. Correct insertion of disk in the disk drive is essential, otherwise some data stored on the disk is

likely to be destroyed or the disk itself may get damaged.

The diskette should be inserted slowly in the disk drive only when power to the entire computer system is on. It

should be removed prior to turning the system off.

As a defensive measure, it is advisable that a back-up copy of the information stored on each diskette be pre-

pared and stored separately at a safe location. The diskette should be properly labeled for right identification.

While storing a diskette, both physical and environmental factors should be considered. Diskette should not be

stored in such a way that may sag, slump or compress it.

The main enemies of a diskette are temperature and direct sunlight, dust, liquids and vapors and electromagnet-

ic interference. Diskette should be protected from them. Care should be taken to clean the disk drive head to

remove dust regularly.

Floppy diskettes are very cheap and offer both sequential and direct access to data at a substantially high

speed. Typically, data may be transferred at the rate of 30,000 to 1,50,000 bytes per second.

.

Floppy disk drives are generally smaller and more economical to manufacture than rigid disk systems. That is

why these are used as auxiliary storage and I/O media with mini and microcomputer installations, at present

the Compact disk has taken the lead in the market. In Mainframes also, these are being used as input medium.

1.8.2 Magnetic Disk (Hard Disk):

Magnetic disks are higher version of Floppy. In place of using one plastic film of double sided as in

floppy, magnetic disc uses so many surfaces of metal plates which are more rigid than the plastic film

in floppy which will increase the storage capacity. Magnetic disk surface is also divided into tracks and

further divided into sectors. These so many surfaces together are attached on one simple like a stack of

disk. The same track no. of every surface is aligned and makes a structure known as cylinder.

Unlike floppy diskettes, where the disk and drive are separate, the hard disk and drive is a single unit. It

includes the hard disk, the motor that spins the platters, and a set of read/write heads. The terms hard

disk and hard drive are used interchangeably as the drive and disk cannot be separated.

These Stack of surfaces keeps the read and write head (each surface has on read/write head) to read and

write data from and to surface. In there are pack of 5 discs with two surfaces each side then there will

be 10 surfaces to store data. The number of read/write head will be equal to number of surfaces used

for storage purpose.


Magnetic discs are the most popular direct access medium. The capacity of the magnetic disk is much

larger than the floppy disk. Normal capacity of the floppy disk is 1.44 MB whereas in present days the

magnetic disk which is popularly called as hard disk is of 200 GB to 500 GB, 1 Terra byte or more.

Performance wise also the magnetic disk will access the data at much higher speed than the floppy be-

cause of its hard metal surfaces the rotational speed of magnetic disk is much higher than floppy disk.

The hard disk spins 3600 rpm and 7200 rpm instead of floppy diskette’s 300 rpm.

Magnetic disks are packed in the air tight vacuum chamber to make it more reliable and less prone to

damage because of its non exposure to dust, air, moisture etc,.

1.8.2.1 Data Storage

Not only do hard disks pack data more closely together, they also hold more data, because they often

include several platters, stacked one on top of another. To the computer system, this configuration just

means that the disk has more than two sides; in addition to a side 0 and side1, there are sides 2, 3, 4 and

so on. Some hard disk drives hold as many as 12 sides, but both sides of the disks are not always used.

With hard disks, the number of read/write heads specifies the number of sides that the disk uses.

Hard Disk

For example, a particular hard disk drive might have six disk platters (that is, 12 sides), but only elev-

en heads, indicating that one side is not used to store data. Often, this is the bottom side of the bottom


disk.

The computation of a hard disk’s capacity is identical to that for floppy diskettes-but the numbers are

larger. The breakdown of the storage capacity for a disk is given below:

Storage Capacity = No. of recording platters x No. of tracks per platter x No. of sectors per track x No.

of bytes per sector.

For Example, a disk has 12 plates each having 3000 tracks. Each track is having 200 sectors per track,

and each sector can store 512 bytes. The total recording surface would be 11 (total 22 recording surfac-

es, 11 x 2) since upper and lower disk surface does not have recording (r/w) heads.

Total storage capacity = 22 x 3000 x 200 x 512 i.e.675,840,0000 bytes which is equivalent to approxi-

mately 6 GB of data.


The time required to access any data from disk is known as access time. This time is made with three

components.

1. Seek Time: Time taken by read/Write head to move itself from its present position (track) to posi-

tion from which data is to be accessed.

Read/Write head moving from one track to another

2. Rotational Time: Time taken by disk to move itself rotationally and position the start point of data

under the head. Average Rotational time or Latency time is equal to the time taken in half of disk rota-

tion.

3. Data Transfer Time: Time taken to transfer the read data from secondary storage to primary

memory.

The total of these three components is known as the access time and typically ranges from, 8 to 12 mil-

liseconds.

1.8.2.2 Advantages and disadvantages of magnetic disk

The hard disk is most popular auxiliary storage which is used in almost all the micro and personal

computers, notepads, laptops etc,. Inspite of its popularity and advantages it has its own disadvantages.

Below are the advantages and disadvantages of the Magnetic disk.

The advantages of magnetic disk include:

1. Magnetic rigid disk is direct access storage medium; therefore, individual records can be retrieved

without searching through the entire file.

2. The costs of disks are steadily declining.


3. For real-time systems where direct access is required, disks are currently the only practical means of

file storage. Other new types of storage, such as bubble storage, are not widely used yet.

4. Records can be readily updated by writing the new information over the area where the old infor-

mation was stored (Overwriting of the old data).

5. With removable disk packs, a single disk drive can store large quantities of data although all but one

of the disks is offline at any given point in time. However, being offline is not a disadvantage for many

applications, especially batch applications.

6. Interrelated files stored on magnetic disk can allow a single transaction to be processed against all of

these files simultaneously, without reentry and reprocessing of instructions.

The Disadvantages of magnetic disk include:

1. Security of information stored on magnetic disks which are used as shared, is major concern.

2. Regular 'head' crashes can damage the surface of the disk, leading to loss of data in that sector.

3. When new data is stored in magnetic disk, it is stored with a technique known as overlaying in

which new data is stored on old data as a new layer; this will erase the old data. With this type of stor-

age we lack in Audit Trail of previous stored data.

4. Magnetic disk is generally fixed into cabinet and connected to the mother board through cables, so it

cannot be moved so easily from one place to another.

1.8.3 Optical Laser Disks

These are capable of storing vast amount of data, these uses the laser beams instead of read/write head.

One laser beam writes the data on to the recording surface and another laser beam is used to read the

data.

These are highly reliable, compact in size and inexpensive. These disks are circular in shape and divid-

ed into tracks, normally contain large no. of tracks.

These are sequential storage and direct access medium that is one can access any of the tracks on the

disk directly.

The below are the categories of Optical laser disks, CD ROM disks; WORM disks, DVD, and Blu-Ray

1. CD ROM:

This one is the most popular type of optical disk in the market. First of all invented by Phillips Compa-

ny, initially these memories were used for audio data for recording and distribution music. But very


soon CDs become very popular medium to store and retrieve computer data because of its high capaci-

ty, high reliability and low cost. Most of the compact disks in the market are read only disks. That is

once data is written on these disk cannot be altered.

CDs are very inexpensive medium to store large amount of data, a CD cost 10/- can store data of 650

MB. CDs have become universal memories for distributing software. CDs are used for storing all types

of data like audio, video, text or any other type of commercial data.

Because of its low cost and high reliability it is used as universal portable type of memory for transfer-

ring software and data from one place to another. Now a days CD manufacturer has also introduced the

CD-RW that is compact disk Rewritable which allow a CD to be written again and again just like flop-

py. CD –RW are similar to floppy features but has additional high storage capacity and more reliability

and retaining capability of data.

Internet becoming more and more usable medium for sharing information and information containing

lot of graphics which require high memory capacity. In order to save these high memory data for long-

er duration of time the CD-RW would become a necessity and would replace the use of floppy disk.

Finally, we can say CD has gone following technological changes

CD-ROM (Compact disk – Read Only Memory) known as Pre-recorded CD

CD-R (Compact disk – Recordable) known as once recordable CD

CD-RW (Compact disk – Rewritable) known as Rewritable CD

Companies like Samsung, LG, manufacture the CD-ROM drive and CD – Writer.

2. WORM Disks: These are optical memories known as Write once Read Many Times Disks. These

memories are like CD-R and used for storage of historical data permanently. These disks used to have

approx 200 MB capacity for storage of text and image data.

Access times for CD-ROM and WORM drives tend to be quite slow by hard disk drive standards, rang-

ing from 100 to 300 milliseconds.

Another popular application of WORM disks is in information systems that require the merging of text

and images that do not change for a period of time. A good example is an “electronic catalogue”


3. Magneto-Optical Disks and Drives: This Disk integrates the technology of both optical and mag-

netic disks. The disk has the advantage of optical disk of large capacity and re-writable advantage of

magnetic disk. Magneto-optical disk can store approx 1000 MB of data. The drive required for this disk

reading and writing is magneto – optical drive.

This disk is not a popular storage medium and not much in use due to its high cost.

For rewriting the data on magneto optical disk the data can be erased first and write new data or as in

hard drive new data can be written by overwriting the old data which provides a fast data storage.

4. DVD (Digital Versatile Disks or Digital Video Disk): This one is most popular invention in the

family of optical disk. These memories absolutely resemble like CD but can store much large amount

of data than CD. These memories can store and reproduce the data particularly graphics and video data

with a very high quality in comparison to CD. DVD surfaces are divided into Tracks and one can ac-

cess any of these tracks in no time that is access rate of DVD is much higher than the floppy.

Unlike CD, DVD can store the data on both sides and can have two layer on each side to give larger

capacity. One DVD can store upto 17 GB capacity. There are predictions that DVD would replace hard

disk as storage media because of its high capacity, reliability and quality. Right now most of the use of

DVD is in storing audio and video data for various applications, like in entertainment industry and var-

ious industrial training applications.

Similar to CD evolutions, DVD has also undergone technological improvements from DVD (Read on-

ly) to DVD – RW.

DVD – (Digital Video Disk) – this is Read only storage medium

DVD-R – (Digital Video Disk – Recordable) this can be recorded only one time.

DVD-RW – (Digital Video Disk – Rewritable) known as rewritable DVD.

Various types of DVDs can be used for storing images, text, movies, high resolution graphics etc.

1. DVD-5 holds 4.7 GB data and is supported by the DVD+R/RW and DVD-R/RW formats. It is also

known as Single-Sided Single Layer.


2. DVD-10 holds 8.75 GB data and is supported by the DVD+R/RW and DVD-R/RW formats. It is

also known as Double-Sided Single Layer.

3. DVD-9 holds 8.5 GB data and is supported by the DVD+R and DVD-R formats. It is also known

as Single-Sided Double Layer (sometimes called Dual Layer). The official names are DVD-R DL and

DVD+R DL.

4. DVD-18 holds 15.9 GB data and is supported by the DVD+R format. It is also known as Double-

Sided Double Layer (or Double-Sided Dual Layer).

Video disks were first introduced in 1983, as a video game product. Today, however, they can provide

companies with a competitive advantage. Various usage of DVD has been described which caters the

needs of present day requirements.

1 Video disk systems were developed to help real estate agents conduct better searches for homes and

properties for their clients.

2 Video disks are widely used for training applications. At a growing number of companies –Ford,

chrysler, Xerox, Pfizer, and Massachusetts Mutual Life Insurance, to name just a few-video disk sys-

tems take on such training tasks as showing how to boost factory performance, helping service techni-

cians do a safer and better job, and training clerks to analyze insurance applications. The U.S. Army

has also made extensive use of video disks for training purposes.

3 Video disks are also used by automobile manufacturers to show their lines and by travel agents to

interest clients in resorts.

4 Product Catalogues - This saves money on postage and printing for the company.

5 Shops and post offices - Shops and post offices have small TVs showing promotions and local busi-

nesses. They serve as a marketing tool.

6 Business Presentations - Some businesses have started to use the power of DVD to show more aes-

thetically pleasing presentations. These presentations provide a very professional outlook for the busi-


ness and allow the company to save pictures, text, graphics; video and audio - all of which can be very

large in file size.

7 VHS to DVD Conversion - Converting old training videos to DVD is a good practice. This is be-

cause videos have a limited life span. Eventually the quality is reduced, making it very unpleasant to

watch. Also, if all videos were converted to DVD, the old training videos could be destroyed. This will

make more office space as DVD’s take far less space than a VHS video.

8 Legal - DVD’s are becoming a tool in the legal profession. DVD’s are being used to record video

evidence of a witness. These are used if a witness would like to remain anonymous. This type of evi-

dence is used a lot in high profile cases, where there can be repercussions to the witnesses.

9 Trade Show Demonstrations - For a business to attract crowds, DVDs helps in performing the same.

DVD’s could be used to show demonstrations to the crowds. After all, a product will very unlikely sell

unless if a demonstration of some sort is shown. A DVD is an excellent tool to show off a product

demonstration.

10 Magazine/Programme DVDs - Magazines and programmes are now being converted to DVD for-

mat. A consumer will almost always rather see an interview with a pop star for example, rather than

read it.

5. Blu Ray Disc : Known as Blu-ray Disc (BD), is the name of a next-generation optical disc format

jointly developed by the Blu-ray Disc Association (BDA), a group of the world's leading consumer

electronics, personal computer and media manufacturers .The format was developed to enable record-

ing, rewriting and playback of high definition video (HD), as well as storing large amounts of data.

The format offers more than five times the storage capacity of traditional DVDs and can hold up to 25

GB on a single-layer disc and 50 GB on a dual-layer disc. This extra capacity combined with the use of

advanced video and audio codes that will offer consumers an unprecedented HD experience.

While current optical disc technologies such as DVD, DVD±R, DVD±RW, and DVD-RAM rely on a

red laser to read and write data, the new format uses a blue-violet laser instead, hence the name Blu-

ray.

The benefit of using a blue-violet laser (405nm) is that it has a shorter wavelength than a red laser (650nm), which makes

it possible to focus the laser spot with even greater precision. This allows data to be packed more tightly and stored in less

space, so it's possible to fit more data on the disc even though it's the same size as a CD/DVD. This together with the

change of numerical aperture to 0.85 is what enables Blu-ray Discs to hold 25 GB/50 GB data. Recent development by

Pioneer has pushed the storage capacity to 500 GB data on a single disc by using 20 layers.

Some analysts suggest that the biggest obstacle to replacing DVD is due to its installed base; a large

majority of consumers are satisfied with DVDs.


1.8.4 Magnetic Tape and Tape Cartridge or Tape Devices

The magnetic tape is a continuous length polyester film coated with magnetic material. It is a sequen-

tial data storage and access media. The tape is normally of 2400 ft. in length and ½” in width. The full

length of tape is divided in tracks it can be 7 tracks if coding system is BCD, 6 for code 1 for parity bit,

8 tracks for ASCII and 9 tracks for EBCDIC. New technology magnetic tapes are coming with multiple

tracks like 32 tracks for ASCII for faster transfer of data. Recording densities of tapes are represented

as Bytes per inch (bpi).

The storage space to store one character on tape is known as frame and number of frames together will

make record and number of records makes a structure called as block. After every block there is gap

(Inter Block Gap) or Stop/Start gap. This gap is provided so that tape can read a block of data and stop

for while to transfer the data read into CPU and then start reading again next block.

Some important terms used in magnetic tape.

1. IBG (Inter Block Gap): The gap for Start/Stop operation of tap while reading the data.

2. RM (Record Mark): A small gap provided for variable length record structure to distinguish between

two records.

3. Tape Mark: If more than two files are placed on a tape, then the gap between the files is called Tape

mark.

4. Blocking: Placing of so many records together in a block.

5. De-blocking: Separating records from block.

Here we will look at the two most popular forms of magnetic tape for large system MIS applications:

Detachable reel magnetic tapes and Tape cartridges.

1. Detachable Reel Tape: This is an old magnetic tape technology and in this two open spools are

used, one spool used to supply the tape and other spool takes up the tape. An empty take-up reel, run-


ning at the same speed as the supply reel on which the tape is initially wound, accepts the tape as it is

being processed.

The tape is processed by passing it under read/write heads located between the two reels. Depending on

the instructions given to the computer system, data can then either be read from the tape or written to it.

Detachable Magnetic Reel Tapes

2. Tape Cartridge: Cartridge tapes represent the leading edge of tape technology. Tape cartridges are

available for both large and small computer systems. The Tape Cartridges are like Audio cassettes.

These are also known as streaming tape. In 1986, IBM introduced Tape cartridge system. Tapes are

small in size and can store large amount of data than conventional detachable reel tape.

Each of these cartridges has a capacity of 200 MB and a data-transfer rate of 3 MB/Sec and further

models tape drives ranging from 800 MB to 60 GB of storage capacity.

These tapes have 32 or 36 tracks depending on the coding system. To use a tape cartridge a Tape car-

tridge drive is required in the computer.

Examples - Tape Recorders, used to play the Audio or VCD players used for Videos and also.


Case Study 1

The Xerox People Net Story- Use of Information Technology in Business organisation.

Background

With revenues of $ 18.7 billion in the year 2000, Xerox is a global leader in the document management

business. The company offers a vast range of document products, services and solutions in association

with its joint-venture partner, Fuji Xerox Co. Ltd. of Japan. The products include digital printing and

publishing systems; digital multifunction devices and copiers; laser and solid ink printers; fax ma-

chines; document-management software; supplies (toner, paper, ink cartridges, etc.); and comprehen-

sive document-management services such as running in-house production centers and developing

online document repositories.

The Challenges

In the early 1990s, Xerox saw media reports commenting that the functioning of the company's HR de-

partment was 'hardly a model of efficiency.' The company realized that the fully centralized functions

of hiring, awarding bonuses and granting promotions were resulting in the central HR department being

over-burdened. More often than not, HR personnel were tied up in paperwork that left them little time

to use their skills elsewhere. As a result, tasks such as counseling managers on ways to handle employ-

ee problems were frequently postponed by HR managers. Xerox was not happy with its internal job

posting process as well. In the existing setup, hiring managers filled in job description forms and sent

them to the HR department, where the information was reentered on posting forms.

It often took a week before employees could view the job listings, thus delaying the recruitment pro-

cess considerably.

The Solution

In 1992, Xerox began to explore the possibilities of using a computer system to release HR profession-

als from the monotony of administrative tasks. The company decided to install an intranet application

to act as a communication and productivity tool for its 50,000 managers and employees. The idea was


to deliver traditional human resource information such as benefits, compensation, policy manuals,

phone directory and training as well as the ability to change personal information like name and ad-

dress, to minimize the HR administrative support needed by employees. It was thus decided to develop

the required HRMS in-house. This marked the beginning of the Xerox PeopleNet initiative.

Developing Xerox PeopleNet

In June 1993 Xerox began with an internal HR survey to identify the desired objectives of the proposed

system.

The company's existing infrastructure comprised workstations and the basic networking hardware un-

der a mainframe environment. However, mainframe technologies were not user friendly enough for the

typical manager/employee skill set.

Also, Xerox was shifting from the existing hardware setup to a personal computer (PC) setup. There-

fore, client/server architecture was decided upon as the best choice. The development team along with

the company's 'Global Process and Information Management Group' (GP&IM) began establishing the

basic application/system standards for a technical framework. Prototyping was used to test different

development approaches and design the overall graphical user interface (GUI).

The infrastructure support was outsourced from a leading IT services company, Electronic Data Sys-

tems. All the software developed was put through strict compatibility testing to ensure that it complied

well with other Xerox applications and standard configurations.

By the end of 1994, a pilot was developed, which was approved by the company and funds were re-

leased for the production version. In January 1995, a read-only version was launched with simple ap-

plications. Xerox opted for a phased launch because it was shifting from mainframes to a PC based set-

up and the developers needed to understand the new infrastructure well before going in for a full-

fledged implementation.

The project followed a phased development approach of prototyping, testing, re-testing and then rolling

out on a continual basis. Visual Basic was selected as the client development tool because of its ability

to facilitate prototyping. The Microsoft Access engine acted as the invisible middleware component,

which tracked configuration and routing information and stored cached data.

To get the software to the users, Xerox adopted various delivery strategies, viz, shipping to local sys-

tem administrators, using CDs and floppy disks, the company intranet. To access Xerox PeopleNet,

employees had to enter both their social security number and a Xerox PIN number.

The software used application-level encryption for passwords as well as transmission-level encryption

for data traveling over the network. As the company was shifting to a PC-based setup, implementation

of the system was rather slow and had to be in a phased manner.

As the hardware setup stabilized and more features were added, Xerox PeopleNet became increasingly

popular within the organization.

The Benefits

Xerox PeopleNet supported applications covering such areas as training, retirement fund performance

and a corporate phone directory. In addition, employees could check Xerox's stock price as well as

those of its competitors. The unique feature of Xerox PeopleNet was that unlike typical HRMSs, it did

not restrict the availability of information HR staff alone. All employees could access information

through any PC on the company's network. Xerox PeopleNet cost Xerox around $2 million. However,


its benefits far outweighed the investment. The solution helped Xerox accomplish its objectives of em-

powering its people, increasing satisfaction and boosting productivity.

In addition, online publication of the human resources manual and other publications saved approxi-

mately $1.5 million annually in printing costs.

Online transaction processing and electronic signature approval capabilities added later saved another

$1.1 million annually by eliminating manual forms and paper-based processing.

On the hiring front, managers could open the Xerox PeopleNet application on the desktop, create a

posting on an online form and post it immediately on a central electronic bulletin board.

Any interested Xerox employee could then print an application form and submit it to the hiring manag-

er in paper form. The paper element was to be completely eliminated over a period of time and internal

job applications were to be processed entirely online.

The system included a feedback feature that let employees suggest new ideas and improvements. As a

result, employees were able to monitor their profit sharing and retirement plans and change their con-

tributions from their desktops itself.

Interestingly, Xerox PeopleNet seemed to have had certain undesirable results as well. Commenting on

the massive layoffs by Xerox during the 1990s, analysts said that so long as software such as Xerox

PeopleNet continued to render personnel redundant, the trend of manpower trimming was likely to con-

tinue.

Case Study 2

NAS Case Study: The International Image Processing Company

Overview

The International Image Processing Company, or IIP, provides a proprietary digital imaging service to

academic, educational, and government institutions throughout the United States. Its computer imaging

services provide clients with the ability to transfer physical documents, such as historical books, docu-

ments, and newspapers, as well as photographic images, such as historical photos, video images, and

medical images, into digital media. The company’s clients range from major universities to some of the

largest archival government institutions.

Despite the scope of its clients, IIP is a small business with less than $5 million in revenues, with plans

to grow threefold in five years if it can increase its capacities to bring on more clients. IIP has a small

but distributed business organization with headquarters in Texas and major client work sites in New

York City, Washington, D.C., and San Francisco. Due to the nature of IIP’s work, its IT staff is inte-

grated into the specialized work force that the company employs—given the digital scanning software

and processes that are integral to their work. The company also employs two dedicated IT techni-

cians—one for hardware and another responsible for infrastructure software. Additional IT related ac-

tivities are handled through the imaging software support and configuration personnel.

The company was challenged by its dependencies on storage, created through its software scanning

processes that were increasingly exacerbated by new clients. Daily operations could quickly utilize a

terabyte of data storage. Because the imaging scanning product was archived to clients using both opti-

cal and tape storage devices, if operations ran short on available storage, the imaging processes would

slow and eventually stop until sufficient space was freed up for operations. This slowed billing and

eventually cash flow.


The storage situation reached critical levels that started to impact the company’s ability to handle new

clients and subsequently impacted its planned business growth.

IIP was in the classic predicament of needing a high-performance solution, while being restricted by a

minimum budget and a limited IT staff. The evaluation of potential storage solutions ranged from stor-

age area networks (SANs) to IDE RAID solutions. While a network attached storage (NAS) solution

would satisfy the size requirement, NAS remained a problematic solution because it also had to be

managed remotely at the New York, Washington, D.C., and San Francisco sites.

IIP chose a general-purpose solution, even though its processes were largely proprietary, which was a

matter of thoughtful strategy on IIP’s part to utilize standard hardware and OS platforms. The NAS so-

lution was chosen for its ability to integrate easily into a small IP environment, while being able to de-

ploy remotely with some level of remote management.

This case study will discuss the IIP storage and related processing problems and challenges in detail.

These drove the activities involved in identifying the company’s workload and analyzing potential

storage solutions. Finally, we discuss how IIP concluded with the decision to implement NAS and the

subsequent transition to the new storage model.

The Situation Analysis

IIP developed its storage solution from years of experience in scanning and duplicating photographic

images, ranging from military applications to historical documents. The challenges had always been the

time required to scan an image, versus the quality required for large clients. This had given way to the

amount of space required for each image, given that the IIP client base dealt with millions of images.

The type of work IIP performed was not directed toward the market of flatbed scanners nor even larger

scanners in terms of quality and production process requirements. Instead, IIP developed a process and

proprietary software that used specialized digital cameras to scan images of various dimensions, physi-

cal states, and types-various papers, photographic techniques and types, and so on. The process, cou-

pled with the scanning stations, provided a production-oriented environment where imaging could take

place 24/7, if required. The process and software included a fully complete life cycle of imaging cap-

ture, correction, and quality assurance before it was placed on a CD or tape for shipment to the client.

Clients of IIP had requirements to digitize documents and photographs to provide a wider distribution

and availability of these items through the Internet. Consequently, these clients had become part of the

growing movement within both the academic community and public sector to save historical docu-

ments. For the most part, these markets are just emerging, given the tremendous amount of material

that remains to be scanned and digitized.

IIP's client requirements could run into the 500,000-plus number of images for a single project. That

type of work drove the production-oriented environment introduced by IIP in the late 1990s.

IIP Systems Infrastructure

IIP maintained a distributed infrastructure with its headquarters in Texas and field locations in New

York, Washington, D.C., and San Francisco. Figure A-1 illustrates the configurations at the headquar-

ters' locations. Here you see the integration of capture stations, process servers, correction/quality as-

surance workstations, database servers, and archive servers. Each field location is set up in an identical

fashion. Each is linked to the headquarters' network and web server through a virtual private network


(VPN). E-mail and FTP services are handled in this manner. Architecturally, this setup was designed

for future development of remote scan processing and diagnostic imaging services.

The imaging process will describe the storage utilization scenarios and why the process is so data-

centric.

Problem Details

What IIP had not foreseen were the systems infrastructure requirements for this type of production

work. This required the calculation of both processing cycles and, most of all, the amount of storage

space that would be needed on a daily operational basis. Because IIP is a small business, it had resisted

a formal capacity plan and had relied on its ability to respond quickly when additional capacities were

needed. That meant the additional servers were purchased on an 'as-needed' basis, with most of the

hardware being 'do-it-yourself' built chassis and motherboard configurations.

With this orientation to developing and maintaining the hardware portion of the systems infrastructure,

the storage challenges were met with larger and higher speed internal IDE disks. This gave rise to addi-

tional server installations that were needed to handle the post scan image processing. This then prompt-

ed the acquisition of dedicated media servers to write out the client images using CD or tape media.

This is the archival system on the backside of the process .This meant that a faster network was neces-

sary to speed the transmission of scanned raw files to the process servers, and ultimately it placed the

problem back at the storage infrastructure once again as the image scans overtook the capacities on the

servers.

A stopgap effort was a move to IDE RAID to provide adequate storage for the process servers. This

was largely driven by the 'do-it-yourself' mode of the hardware and severe limitations of budgets con-

straints. Although the IDE RAID facilitated a quick fix, IIP's flexibility in providing reliability and

backup protection was problematic. In many cases, the volatility of the data movement over the period

of one week could easily surpass more than five terabytes running through a single process server. As


the tremendous write activities continued, the IDE drives generally failed twice a month, with minimal

success running data protection with RAID level

1. However, the space it provided offered a brief interlude to the space problems that shut down the

process entirely.

Given that additional business was coming in with more restrictive time constraints for completion, IIP

concluded that a longer term solution had to be found.

The Search and Evaluation

The IIP hardware and software IT personnel researched the solution along with assistance and input

from the imaging software specialist. They found that a SAN was a valid consideration, since it ap-

peared to be the choice of others working with unstructured data such as video and audio projects.

However, they found that the imaging system, although proprietary by its methodology, used open and

commodity levels of hardware and operating environments and was further open to additional solutions

that integrated well into the small business environment. Another alternative was to move to larger

process servers with external SCSI drive arrays, to scale up in both process and storage power. Yet an-

other alternative was the consideration of a NAS solution, which would integrate easily with the exist-

ing network, would use file systems, and would have the capacity they needed.

Estimating the Workload

The IT personnel, working with an outside consultant, identify the company workloads. They further

moved to understand the types of configuration needed for all three possible alternatives. First looking

at the SAN configuration, followed by the larger server with external RAID, and finally the potential

NAS configuration. The results are summarized in the following sections.

Workload Identification:

Looking at a year's history of scanning images, the IIP team concluded that the workload was complex

and data-centric, and it fit somewhere between online transaction processing (OLTP) and data ware-

housing. The workload encompassed OLTP characteristics when scanning the image and then transmit-

ting the write transaction to the process server. Although developed as a synchronous process, it was

recently changed to an asynchronous process to facilitate greater throughput at the capture station.

However, this still required a sequential write process at the process server as each image was scanned.

On average, the image scans were 300MB in size. The calculation of 300 images per shift x 3capture

stations working two shifts provided the necessary throughput. It was determined that at least 540GB

of free space was needed to accommodate the daily scanning process. This required that the overall

storage infrastructure be able to accommodate a 566MB per second throughput rate.

Workload Estimates for SAN:

we can quickly calculate that the required components for a SAN which could be handled by one, 16-

port switch, given that a single point of failure is acceptable for the installation; or it could be handled

by two, 8-port switches for some level of redundancy. Three HBA adapters with 2 ports each for re-

dundancy and performance would be required for the process servers. However, not to be overlooked,

this configuration will require additional Fibre Channel storage arrays to accommodate and be compat-

ible with the new Fibre Channel storage network. Given that the total capacity of 540GB needs to be

available every 24 hours, we can estimate that two storage arrays of 500GB each would provide the


necessary capacity with sufficient free space to handle peak utilization as images are processed through

the system.

Workload Estimates for Direct Attached Storage:

Aligning the requirements to new servers, we find that all the process servers would have to be upgrad-

ed. This would also require that the storage capacities be carefully aligned with each process server.

Even with this alignment, specific workload affinity would have to be observed to utilize the storage

effectively. On the other hand, the process server could more easily share storage across the network

but would have to reflect some level of duplication for storage requirements to accommodate the total

capacity, essentially doubling the entire storage requirement.

This would require, in addition to new servers installed, OS software upgrades, with appropriate

maintenance and all the necessary activities of a major system installation. It would result in a normal

disruption of service and reliability characterized by new system installations. However, the new serv-

ers would have to be configured to handle the I/O throughput of an aggregate of 566MB per second.

This would require each server to handle 188MB per second if the workload is evenly distributed,

which in most cases will not be the case; however, we will use this for estimating purposes. That re-

lates to a minimum of six Ultra-wide SCSI-3 adapters necessary to handle the sustained rate of 188MB

per second. This requires the total storage to be divided among the servers, and subsequently the adapt-

ers, and places a limitation of approximately 120GB per Logical Unit Number. Thus, a more complex

management problem in terms of flexibility of reconfiguration based on required storage would be nec-

essary, given that one capture station could generate 180GB of images every 24 hours.

Workload Estimates for NAS:

We can calculate that our workload requirements are definitely within the mid-range NAS device con-

figuration and probably just under the enterprise NAS solutions.

We can select mid-range even though our sizing factor is within the enterprise range. This is based on

the special application circumstances and because the aggregate data is below a terabyte and would be

physically segmented within the aggregate data capacity estimate. In addition, we considered the work-

load being further characterized by limited users working with an almost dedicated Gigabit Ethernet

network.

The NAS solutions also offer the flexibility of storage incremental selection-for example, installing two

large NAS servers and one small server, or one large and two medium-sized servers. These solutions

also provide the flexibility of RAID processing, network compatibility, and non-disruption to the exist-

ing server configurations. In addition, these solutions can be easily configurable to support the scan-

ning projects and mapped as network drives with the same flexibility. They will also provide a closed,

yet remotely accessible, solution for the remote network configurations.

One last word on our estimating process: We recognize the characteristics of the small integrated IT

staff and the company's lack of any formal capacity planning activities. The process of workload identi-


fication and estimates provides this company a level of direction and planning. The result of this exer-

cise has identified that the mid-range NAS devices can meet the company's workload now and within a

limited planning period. However, it also provides an insight into future challenges IIP will encounter,

as its staff has become aware that it borders on moving into enterprise solutions of either the NAS type

or probably a SAN if the budget for infrastructure can support either.

The IIP NAS Solution

The final configuration provides increased storage capacity and enhanced performance. The IIP scan-

ning process is now being up-scaled with new customers and imaging projects. In addition, the space is

being utilized on an automated basis from new project initiation to deletion after delivery. Figure A-3

illustrates the NAS configurations that support the revised IIP systems infrastructure.

Figure A-3’s NAS configuration illustrates the increased capacity for storage of images, but it also pro-

vides the foundation for image access through the Internet. This was designed into the system to allow

the remote work sites that have identical installations to upgrade to NAS devices. Over and above the

increased capacity at all sites will be the potential ability to access images across the IIP storage net-

work infrastructure. In other words, images scanned in New York could be evaluated in Texas, Wash-

ington, D.C., San Francisco, or other remote offices as they begin operation. This is an added business

efficiency that takes advantage of the imaging expertise across the company without regard to location.

It also allows clients eventually to be provided test and quality images through the Internet to further

facilitate the delivery and client acceptance process.

In summary, the NAS solution turned out to be a good fit for IIP. Even though its application appeared

to have many proprietary processes and software processes, NAS operated within the bounds of lever-

aging commodity infrastructures for networks, systems, and storage. With the exception of the database

server, all the servers within the IIP infrastructure now share the available storage in the NAS devices.

The acknowledgment of this value further expands the use of the NAS solution as the company began

to configure its web and imaging software code development on the NAS devices.


The NAS solution for IIP provided a cost-effective solution for a small company, but it also provided

the company with the necessary storage resources for expanding its business, which had grown de-

pendent on a storage-centric product. The company’s storage infrastructure is now poised to grow into

the future with either more sophisticated products such as a SAN, or to continue to scale economically

with further uses of NAS devices. Either way, IIP now has the business flexibility to meet the growing

dynamics of the imaging business.

MULTIPLES CHOICE QUESTIONS

1. Who was the inventor of First fully programmable mechanical computer called Analytical Engine?

a) Charles Babbage b) Herman Hollerith

c) Blaise Pascal d) Howard H. Aiken

2. Which one was the first General purpose electronic Computer?

a) UNIVAC b) EDVAC

c) ENIAC d) None of the Above

3. Which Technology was used in Third Generations of Computers?

a) Vacuum Tubes b) Transistors

c) Integrated Circuits d) None of the above

4. The ___________generation of computers are able to perform voice recognition

a) Second b) Third

c) Fourth d) Fifth

5. A computer that performs calculations and logical operations with quantities represented at digits is

known of _______

a) Analog computer b) Digital computer

c) Hybrid computer d) None of the Above

6. Mark – 1 is a type of _____________

a) Supercomputer b) Mainframe computer

c) Mini computer d) Micro computer

7. The processing speed of the super computers can be measured in

a) FLOPS b) TFLOPS

c) PFLOPS d) All of the above

8. Workstation is used which kind of CPU architecture?

a) CISC b) RISC

c) SISC d) None of the above


9. _________runs on a network of computers and enable sharing of printers and other equipment be-

tween various computers on the network

a) Sever b) Processor

c) Workstations d) Peripheral Device

10. Which of the following is an example of volatile memory?

a) ROM b) PROM

c) SDRAM d) None of the above

11. CPU chip is made of __________

a) Carbon b) Copper

c) Silica d) None of the above

12. Which of the following units performs the calculations and comparison/decision activities?

a) Control unit b) ALU

c) Output unit d) Storage unit

13. Which unit is responsible to interpret the instructions provided by the other units?

a) ALU b) CPU

c) Control unit d) None of the above

14. The processing speed of CPU can be measured in _________

a) MB b) KB

c) GB d) MHZ

15. Which of these is the fastest memory type?

a) Primary cache b) Secondary cache

c) Main memory d) None of the above

16. A small chip on the motherboard that loads the hardware setting used for keyboard, monitors, or

disk drives is called _________.

a) CMOS b) PCI

c) BIOS d) None of the above

17. Which storage system is used in enterprise, scientific and business computing?

a) Network Attach storage b) Tertiary Storage

c) Off-line storage d) None of the above

18. The capacity and performance of the computer system can be measured in terms of _________.

a) Storage density b) Latency


c) Throughput d) All of the above

19. How many transistors and electronic computers a VLSI chips has?

a) From 3000 to 100000 electronic component per chip

b) From 100000 to 1000000 electronic component per chip

c) More than 1 million electronic components per chip

d) None of the above

20. Magnetic Disc are categorizes as _________

a) Direct Access medium b) Sequential Access medium

c) Index sequential Access medium d) None of the above

21. The time required in positioning a read-write head over the recording track is known as

a) Seek Time b) Rotational Time

c) Data transfer Time d) None of the above

22. The Disk which is used to store large amount of data using optical laser technology is known as

a) CD-ROM Disk b) Magnetic Disk

c) Both A & B d) None of the above

23. The optical disk which is used to store large amount of data, including songs, movies and, Pictures

of high quality is called ___________.

a) CD-ROM b) Magneto Optical Discs

c) Digital Video Disk d) None of the above

24. A Disk which uses both magnetic are optical Technology to obtain high data density ranges from

100 MB to 9 GM of data storage is known as ________

a) Worm Disk b) Magneto-Optical Disk

c) Digital Video Disk d) None of the above

25. The High Definition experience of storing the data on the disk that can store upto 50 GB data on

both side of the disk in known as ________.

a) Blue Disk b) Red Disk

c) Blu-ray disk d) Red-ray disk

Answer:

1. a 2. c 3. c 4. d 5. b 6. b 7. d 8. b 9. a 10. c 11. c 12. b 13. c 14. d 15. a 16. c 17. b 18. d 19. b 20. a

21. a 22. b 23. c 24. b 25. c

SELF-EXAMINATION QUESTIONS


1. Describe in detail various generations of computers.

2. Write short notes on the following types of computers:-

(i) Digital computer (ii) Analog computer (iii) Hybrid computer

(iv) Super computer (v) Mainframe computer (vi) Mini computer

(vii) Micro computer (viii) Workstations (ix) Server

3. Discuss advantages and limitations of computer system.

4. Draw the schematic diagram of a computer. Briefly discuss each of the components covered in it.

5. What are the features of the Central Processing Unit?

7. Discuss various components of a motherboard.

8. What do you understand by the term 'Bus'? Discuss three types of bus available on a computer.

9. Discuss, in brief, various types of storage used for storing the data in computer.

11. Write short notes on the following:

(i) Integrated Circuits

(ii) RAM

(iii) ROM

(iv) Bubble memory

(v) Flash memory

12. Write short note on floppy diskette as an input medium.

13. What are the factors that determine the number of characters that can be stored in a floppy diskette?

14. Differentiate between floppy diskettes and hard disks.

15. Briefly explain the various characteristics of a hard disk.

16. What are the advantages and disadvantages of direct access storage?

17. A disk has 24 plates, each having 2000 tracks. Each track is divided into 100 sectors per track, and

each sector can store 1024 bytes. Calculate the total no. of bytes (GB) a disk can store on both sides of

the disk surface.

18. Explain the following terms:

(i) CD-ROM

(ii) WORM disk

(iii) Magneto Optical Disks

(iv) Digital Video Disk

(v) Blu-ray Disk

(vi) Detachable Reel Magnetic Tape

(vii) Tape Cartridge Systems

CASE BASED QUESTIONS

1. Dr. Kartik is the director of an autonomous institute of Weather and Economic forecasting. He is

planning to setup a new state of art research centre for weather forecasting that would predict the eco-

nomic growth of the country based on agriculture production. He is also planning to setup an educa-

tional institute for students of weather and economic research, providing bachelors, masters and PhD

degree. Dr. Kartik has the responsibility to setup the centre. He is involved in planning, coordinating,

controlling and administrating all the activities including building and infrastructural facilities, pur-


chasing hardware and other equipments and so on. He has all the budgetary approval for these facili-

ties.

Exercise

a) What type of computers should Dr. Kartik procure for the research centre for weather and economic

forecasting and Why?

b) What type of computers should Dr. Kartik procure for the education institute for weather and eco-

nomic forecasting and Why?

c) What will be the budgetary implication of decisions to procure computer systems by Dr. Kartik. Ex-

plain.

2. Mr. Rahul is working as a Research Officer in Internet based multinational consulting firm in Del-

hi. His main job is to provide the support to the existing clients and gather the information about future

clients so that company would be able to give necessary clientele support in near future. For the pur-

pose of making MIS reports on daily basis, it is very much required to connect to the people providing

blogs over internet all the time, the system must be very fast and efficient enough to respond quickly

and also equip with latest technology to work upon various application in integrated environment.

Earlier he was working with PIII computer with 80GB HDD, 256 RAM, CD_ROM,1.44 inch Floppy

drive, Color Monitor and Internet Dialup connection. The performance was not so good over the years.

Mr. rahul has requested to provide new computer system with latest technology. The company has giv-

en the approval to purchase a new system with latest configuration with minimum price. Rahul has

started searching various computers in the market ranging from Rs. 20000 to Rs. 50000 based on

whether they are branded or configured.

Exercise

a) What type of computer system Mr. Rahul would like to purchase? Is there any specific type of com-

puter is available in the market? Explain.

b) What type of configuration Mr. Rahul would like to see and take the decision to purchase the system

that satisfy the requirements of his job responsibility ? Explain.

c) What will be the budgetary implication of decisions to procure computer systems by Mr. Rahul ?Ex-

plain.

info tech - ipcc unit 1

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