MBA – 1 ST SEM NOTES M. D UNIVERSITY, ROHTAK

SUBJECT: COMPUTER APPLICATION IN MANAGEMETN

Q. What Is a Computer?

Ans. The word computer came from the Latin word “COMPUTARE” that means to calculate. Obviously one of the most important functions of the computer is to do calculations. Besides this, it can do many more tasks.

Many definitions can be found in many books. The feasible and understandable definition of the computer would be the following.“It is an electronic device which can perform predefined arithmetical and logical operations in an orderly manner without any error.”

OR“It s a digital device which receives input, stores it, processes it and finally gives a desired output but all under the control of a set of instructions which are called programs.”

Simple Input/Output System

Q. Functional Component of Computers?Ans: - A computer consists of three main units as given below:-

1) Input Unit2) Central Processing Unit3) Output Unit.

A) Input Unit

An Input unit means a device to feed instructions and data to a computer. The data and the instructions coded in an appropriate language are provided to the computer through this unit. The user has an access to the computer through this unit only. Some of the popular input devices are Keyboard, Mouse, Joystick, Track Ball, Punched Cards, and Light Pen etc.

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INPUT PROCESING

OUTPUT

B) Central Processing Unit

It is a major unit, which controls all other units or parts of a computer. It further consists of:i) Center Processing Unit (CPU): The combinations of ALU and CU; of a

computer is called CPU, and the CPU of a Micro-computer is called the Microprocessor. Arithmetic Logical Unit (ALU) carries out sorts of arithmetical calculations like addition subtraction, and supervises the functions of all the other unites. It works very similarly to the active part of human brain which keeps coordinating all body-movement.

ii) BUS- Buses are actually lines and circuits that carry signals to and from the CPU. There are three types of buses viz: Address Bus: It originates from CPU; any access of data from the memory depends on the address sent by the CPU through these address buses. Data Bus: It carries data to and from the CPU. Unlike the address buses, these are bi-directional, carrying data both ways. Control Bus: It carries the control signals from the CPU to coordinate the other internal and external device that works with the CPU.

iii) Memory Unit: The memory unit is the area where the computer stores data and instructions. There are two kinds of memories: Internal memory and External memory. Internal memory are Random Access Memory (RAM) and Read Only Memory (ROM) and External memory is a Hard Disk etc.

iv) Secondary Storage Media: Since the contents in RAM are erased with the loss of electric power, it becomes necessary to store the data for future use. The programs or data can be stored into these devices permanently in the form of magnetic sports. Information stored in the devices can be processed by downloading to the computer whenever it is required. Ex. Floppy Diskette, Hard Disk, Compact Disk (CD-ROM), Magnetic Tape etc.

C) Output Unit

We get raw as well as processed data either in visible, audible, or printed from through this unit. It provides the communication between the computer and user. The results of various operations are communicates to the user through output devices like: Visual Display Unit(VDU), Plotters, Speech Synthesizers, Printers etc.

Q. CLASFICATIONS OF COMPUTER?

Ans: - On the basis of functions: Computers can be classified into three different categories.

1. Analog: It operates on mathematical variables that change with continuously varying physical qualities such as, electric current, pressure, temperature, time etc. Such computers are signal- problem-oriented that is specific to a particular task. Ex. Integrator, Summator etc.

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Limitations of analog computers:-1 These don’t have logical facilities afforded by programming.2 Don’t have the ability to store data in large quantities.3 Cost of implementation of computation is vary high. 2. Digital: It operates with the discrete signals in the form of numbers especially zeros

and ones and process data using standard arithmetic operations.. Such computers are many problem oriented. Ex. IBM-PC, Apple, Macintosh, and other available in the market. Classification of digital computers:-

A. Super Computers: They are the fasters and the most expensive machines, and are considered a national resource. Some of the areas in which super computers are being used are Weather forecasting, biomedical research and aircraft design.

B. Mainframe Computer: Mainframes are installed in large rooms. It occupies a large amount of space due to its accompanying services such as banks of magnetic disk, magnetic taps, high-speed printers, modems sand several terminals. It can perform vary complex scientific calculations, and they are mostly used for scientific purpose. They are also used where the company has its operations in different cities or different countries, such as Banks, or Credit Card companies. More then 100 uses can work at a time same time without degrading its performance.

Ex.: CYBER-76, IBM 3000, UNIVAC 1180 etc.

C. Mini Computers: Physically it may be smaller, in comparison, to the Mainframe, Like the mainframe; many users can simultaneously work on them. It is used for controlling manufacturing processes. They are mainly used in Large business houses. Ex. POP 11/73, HP 300, VAX 11, PRIME etc. D. Microcomputer: We can accommodate it on a desk and only one person

can use it at a time. Therefore, the term Personal Computer (PC) has been given to such computers. These are used for small business, office administration purpose and even in playing games.

Ex:- IBM PC XT/AT, COMPAQ, SCER, AST, EPSON etc.

3 Hybrid: It is combination of analog and digital computers. Which uses a special devices called MODEM to convert analog signal to digital and vice versa. The full form of MODEM is Modulator and Demodulator. Information can be transferred to geographically dispersed areas through computers by use of MODEM.

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Q. CHARACTERISTICS OF COMPUTERS?

Ans:-

SPEED-:

Computers can work are extremely high speeds and much faster then human. The speed of a computer is measured in clock cycle i.e. Hertz (Hz). The time required for the computer to execute basic mathematical operations varies from a few microseconds for small machines to a few nanoseconds or even less for large ones.

ACCURACY:-

Speed is of no use, if the calculations made, have errors, Computers don’t make mistakes by themselves. If a computer is making a mistake then that means that there must be something wrong with program. The computer can make mistake in situations where input is wrong. Hence, if the input data is valid and if the program is correct and reliable, then the computer would produce accurate output.

SOTRAGE CAPACITY:-

The computer can store large amount of instructions, which are called programs, and a large volume of data. There is no need to write the instruction again and again for a similar kind of activity. Computers have devices, which can store programs, the user just need to run them, whenever he needs. Computer can store large volumes of data for a life long period. The most important part is; it is most convenient to process the data and to find the data on a computer.

DILIGENCE:-

Computers never get tired or bored, as in case of human beings. They never feel exhausted by repetitive tasks. And they never take any time switching tasks.

VERSATILITY:-

Computers are experts in every field. They can perform various kinds of tasks. The modern computers can even perform more then one task same time.

SECURITY:-

Computers can provide security to the data. With the help of passwords we can restrict unauthorized users to see the data stored in the computer.

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Q. GERATION OF COMPUTER LANGUAGES?

Ans. Programming Languages are software on which application software are developed. Languages let the programmers make programs, which perform specific functions. Programmers have to use different words for making applications in different languages. Ex. A “Copy” command may be used as “cp” in one language and “copy” in other. Hence a good programming language must have the following characteristics:

Easy Syntax: The words to be used should be simple and must relate to the tasks they have to perform.

Less coding: Languages must support the programmers with common programmers need not write same codes again and again.

Programming languages must provide good debugging tools so that programmers need not compile again and again.

Programs written should be easy to modify or update.

Programming languages should provide all the necessary help files.

Programs written must be hardware independent. Programs should run on all kinds and make of hardware’s.

First generation Language:-

The first generation language was a machine language, which understood only the binary codes i.e. 0 and1. It is also called as Binary language. But this machine language was hardware dependent. Different programs were required for different hardware’s. It used to be very tedious and complex programming.

Second Generation Language:-

The second-generation language was an assembly language. The codes in assembly languages were easy to understand, as they were no more in 0’ss and 1’s. The very purpose of these languages was to bring the man and machine very near toe each other, both using different languages but easily understood by each other.

Third Generation language ( High Level Language):-

It was easier to code in Assembly language as compared to Machine language. But still, there was a need of language, which understands English commands. The languages developed, which were near to English language, for the use of writing the program in 1960 were known as High Level Languages. The different high-level languages, which can be

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used are FIRTRAN, COBOL, BASIC, PASCAL etc. A common man, who need not learn the actual working of a computer in assembly or binary language, can learn these languages.

Fourth Generation language(4GLs):-

The aim behind developing $ GL languages was to cut down on development steps and coding. In a 4GL the user does not directly with the operating system through commands, rather he would interact with a utility software provided by the 4 GL, which in turn will interact with the operating system.

Q: - APPLICATION OF COMPUTER IN BUSINESS?

Ans:-

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Chairman

Board of Directors

President

VPFinance

VPProduction

VP Sales

VPPurchas

e

VPHRD

AccountsOfficers

Production Managers

MarketingManagers

PurchaseManagers

PersonalManagers

EDP/MISManager

Stores/MaterialsManager

The above organizational Chart is given here to show where in the hierarchy the EDP Department comes in. They are basically a service department who interacts with all departmental heads to give them necessary processed information and should be willingly accountable for all data needs of the organization.

We will now look at the various business applications normally computerized.

1 Accounts: - Preparation of Cash Book, Bank Book, Debit Notes, Credit Notes, Invoices, Journal Book, General ledger, Sub ledgers, Trial Balance, Profit and Loss statements, Balance sheet, Cash flow analysis and other accounting statements are prepared using the Accounting System. Accounts Receivable and Payable are also incorporated in this System as sub systems.

2.Inventory Control:- Preparation of Stock Ledger, Consumption Analysis of Items issued under different head of accounts, List of fast moving and slow moving items, ABC Analysis are some of the products of this Systems. Online enquire of stock status of a given item can also be done together with check of expiry date, reordering status, items falling below danger levels etc.

3 Purchase:- Maintains a purchase order file and a Supplier Master File to keep track of Pending Purchases. Vendor Rating, processing of Quotations and placing a purchase order is carried out by a good purchases made in a given period, item wise purchase details etc. are produced as and when necessary.

4. Sales:- Apart from maintaining the sales master, sales order and other required files, order Processing, Delivery challans, Invoicing, sales returns, sales analysis re done by this System. Non availability, picking List, Pending sales date of delivery wise, salesmen wise and customers wise sales analysis, region wise sales reports are also prepared.

E. Payroll:- On acquiring a new computer in an organization, normally payroll system is the one which is computerized first since the procedures and calculations are well defined even in a manual payroll system. Preparation of pay slips, coinage analysis, department wise earning and deductions, provident fund returns, Income Tax statements etc. are also the bye products of this system.

F. Fixed Assets Inventory:- Monitoring of Fixed Assets, their evaluation, depreciation calculations based on different methods and preparation of the schedule of fixed assets are the main activities of this sub system.

G. Budgetary Control:- Creation and maintenance of the budget master file, Reports of expenditure approved but not incurred, monthly budget control, budget and expenses for any given period, budget report budget head wise are the components of this system.

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Q. OPERATING SYSTEMS?Ans. An OS is a program that acts as an intermediary between user of a computer and the computer hardware. The purpose of an OS is to provide an environment in which a user can execute programs. The primary goal of an OS is thus to make the computer system convenient to use. A secondary goal is to use the computer hardware in an efficient manner.

Main functions of an Organization System:-

1. Process Management:- A Process is a program in execution. During execution, a process needs certain resources such as CPU time, memory space, files, and I/O devices. At a particular instance of time, a computer system normally consists of a collection of processes. The process management module of an operating system takes care of the creation and deletion of processes, scheduling of various system resources to the different processes requesting them, and providing mechanisms for synchronization and communication among processes.

2. Memory Management: To execute a program, it must be loaded, together with the data it accesses, in the main memory (at least partially). To improve CPU utilization and to provide better response time to its users, a computer system normally keeps several programs in main memory. The memory management module of an operating system takes care of the allocation and de-allocation of memory apace to the various programs in need of the resource.

3. File Management: All computer systems are used for storage, retrieval and sharing of information. A computer normally stores such information in units called files. Processes can read information from files and can create new files for storing newly information. Information stored in files is made persistent by storing them on a secondary storage media such as a magnetic disk. Files provide a natural and easy means of information sharing. That is, a file can be created by one application and then shared with different applications at a later time. The file management module of an o/s takes care of file-related activities such as organization, storing, retrieval, naming, sharing, and protection of files. It allows programs to use a set of operation that characterize the file abstraction and free the programmers from concerns about the details of space allocation and payout of the secondary storage device.

4. Devices Management: A computer system normally consists of several I/O devices as terminal, printer, disk, and tape. The device management module of an operating system takes care of controlling all the computer’s I/O devices. It keeps track of I/O request from processes, issues commands to the I/O devices, and ensures correct data transmission to/from an I/O device. It also provides an interface between the devices and the rest of the system that is simple and easy to use. Often, this

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interface is device independent, that is, the interface is same for all types of I/O devices.

5. Security: Computer system often stores a large amount of information, some of which is highly sensitive and valuable to their users. Users can trust the system and r4ly on it only if the various resources and information of a computer system are protected against destruction and unauthorized access. The security modules of an operating system ensure this. This modules also ensures that when several disjoint processes are being execute same time; one process does not interface with the others, or with the operating system itself.

6. Command Interpretation: A user communicates with the operating system, for using the various system resources, via a set of commands provided by the operating system. The operating system also provides a simple language, known as command language(CL) or job control language(JCL), using which a user can put several commands together from the command set to describe the resource requirements of the job. The command interpretation module of an operating system takes care of interpreting user commands, supplied individually or in the form of command language, and directing the system resources to handle the requests. With this mode of interaction with the system, the user is usually not too concerned with the hardware details of the system, or with hoe the operating system will direct the hardware to handle certain requests.

UNIT-II

NETWORKS

Networks are an inter connection of computers. These computers can be linked together using a wide variety of different cabling types, and for a wide variety of different purpose.The basis reasons why computers are networked are-

1. To share resources (files, printers, modems)2. To share the same data (Airways or Railways ticketing)3. To share application software’s such as Databases etc.4. Increase productivity.5. Data security, if all the data is placed at one place, it can be efficiently secured.

Components of Networking-

There are three main components of networking namely A sender, A receiver and the communication channel which connects them. The data send by the computer is in Digital signals, but the communication channel that is the telephone line, carries analog signal. Hence we need devices, which can convert these signals. Such a device is called a modem. Tacking an example of communication through computers:

1. Sender computer : The sender of the message will give instruction to the sender computer to transmit data to the receivers address. Now the computer will transmit the data in digital signals.

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2. Sender modem: Communication cables work on analog signals, hence the modem on the sender’s end converts the digitals signals into analog signals and transmits the data. In case the communication is with computers placed near by, they can be connected by a simple networking cable called a LAN cable. In that case a modem is not required because these cables can transmit data in digital signals.

3. Communication Channels: If communication can to be done with a computer placed far away, then the most common communication channels used these days are telephone lines. Telephones lines carry the information in analog format from one place to another. If the distance between two computers is vast, then satellites are also used.

4. Receiver’s Modem: A modem is also required at the Receiver’s end, to convert the analog signals into digital signals, which can be understood by the Receiver’s computer.

5. Receiver’s computer: Receiver also requires a computer to read the message received. The receiver can view the message and reply to message immediately. In that case the receiver’s computer and modem acts as sender’s computers and modem, and the cycle repeats. Hence same modem and same computer can be used for sending and as well as receiving.

Q. Digital and analog Signals?

Ans. Data is propagated from one point to another by means of electrical signals, which may be in digital or analog form. In analog signal, the transmitted power varies over a continuous range, for ex. Sound, light and radio waves. The amplitude (v) of analog signals is measured in volts and its frequency (f) in hertz (Hz). The higher is the frequency of the signal, the more number of times it crosses the time axis. However, a digital signal is a sequence of voltage pulses represented in binary form.

Voltage

+

0 1/f 2/f T -

(a) Analog signal

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0 0 0 0 t

(b) Digital signal

Computer generated data is digital whereas the telephone lines used for data communication in computer networks are usually meant for carrying analog signals. When digital data is to be sent over an analog facility, the digital signals must be converted to analog form. The technique by which a digital signal is converted to its analog form is known as modulation. The reverse process, that is the conversion of analog signal to its digital form, at a destination device, is called demodulation.

Q. Bandwidth?Ans. A term used to describe the data-handling capacity of a communication system is bandwidth. Bandwidth is the range of frequencies that is available for transmission of data. A narrow range of frequencies in a communication system is analogous to a narrow road. The flow of information in such a system- its data transfer rate-is limited just as is the flow of traffic in a narrow road. Wider bandwidths permit more rapid information flow. Thus, the wider the bandwidth of a communication system, the more data it can transmit in a given period of time.When dealing with computer input/output devices, we think in terms of character per second. The ASCII code uses 7 data bits per character plus a parity bit. For data communication additional bits are added to control the process. Although the number of bits dependent upon the communication system used, commonly encountered systems use a total of either 10 or 11 bits per character. Hence a terminal having a speed of 30 characters per second would probably be used with a communication system, which transmits at the rate of 300 bits per second. The communication data transfer rate is measured in a unit called baud. In general usage, baud is identical to bits per second. For instance, a rate of 300 baud of 300 baud is 300 bits per second. Therefore, the 300 characters per second terminal would be said to operate at 300 baud.

Depending on their transmission speeds, communication channels (path) are grouped into three basic categories:-

Narrowband:-

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Narrowband or sub voice grade channels range in speed from 45 to 300 bund. They are used for handling low data volumes and are adequate for low-speed devices. They are used mainly for telegraph lines and low speed terminals.

Voice-band:-

Voice-band channels handle moderate data volumes and can transmit data at speeds up to 9600 baud. They are so called because their major application is so for ordinary telephone voice communication. They are also used for data transmission from slow I/O devices to CPU or form CPU to slow I/O devices. Moreover, most remote terminals are connected to computers through voice-band channels.

Broadband:-

Broadband or wideband-channels are used when large volumes of data are to be transmitted at high speed. These systems provide data transmission rates if 1 million baud or more. A company might use a broadband facility for high-speed computer-speed computer -to-computer communication or for same time transmission of data to several different devices.

Q. NETWORK TOPOLOGIES?

Ans. A network is a logical extension of a data communication system. In a computer network, two or more computers are linked together with carriers and data communication devices for the purpose of communicating data and sharing resources. The term network topology refers to the way in which the nodes of a network are linked together. It determines the data paths that may be used between any pair of nodes in the network. Although the number of possible network topologies is seemingly limitless, the four major ones are the star network, the ring network, the completely connected network, and the multi-access bus network.

The choice of network topology for installing network depends upon a combination of factors such as:-

1. The desired performance of the system.2. The desired reliability of the entire system.3. Size of the system.4. Expandability of the system.5. Cost of the components and devices required to implement the network.6. Delays involved in routing information from one node to another.

STAR NETWORK:-

In the star networking, multiple computers are connected to a host computer. That is, the computers in the network are not linked directly to each other and can communicate only via the host computer. The routing function is performed by the host computer, which

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centrally controls communication between any two other computers by establishing a logical path between them.

ADVANTAGES:-

1. Star topology has minimal line cost because only n-1 lines are required for connecting n nodes.

2. Transmission delays between two nodes do not increase by adding new nodes to the network because any two nodes may be connected via two links only.

3. If any of the local computes fails, the remaining, the portion of the network is unaffected.

DISADVANTAGE:-

1. The system crucially depends on the central node. If the host computer fails, the entire network fails.

RING NETWORK:-

In this topology each computer in the network has communicating subordinates, but within the ring there is no master computer for controlling other computers. A node receives data from one of its two adjacent nodes. The only decision a node has to take is whether the data is for its own use or not. If it is addressed to it, it utilizes it. Otherwise, it merely passes it on to the next node.

ADVANTAGES:-

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HOSTCOMPUTER

1. The ring network works well where there is no central-site computer system.2. It is more reliable then a star networks because communication is not dependent on

a single host computer. If a link between any two computers breaks down, or if one of the computers breaks down, alternate routing is possible.

DISADVANTAGES:-

1. In a ring network, communication delay is delay is directly proportional to the number of nodes in the network. Hence addition of new nodes in the network increases the communication delay.

2. The ring network requires more complicated control software then star network

COMPLETELY CONNCTED NETWORK:-

A completely connected network has a separate physical link for connecting each node to any other node. Thus each computer of such a network has a direct dedicated link, called a point-to-point link, with all other computers in the network. The control is distributed with each computer deciding its communication priorities.

ADVANTAGES:-

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1. This type of network is very reliable, as any link breakdown will affect only communication between the connected computers.

2. Each node of the network need not have individual routing capability.3. Communication is very fast between any two nodes.

DISADVANTAGE:-

1. It is the most expensive network from the point of view of link cost. If there are nodes in the network, then n (n-1)/2links are required. Thus, the cost of linking the system grows with the square of the number of nodes.

MULTI ACCESS BUS NETWORK:-

Computers

In multi-access bus networking, a single transmission medium is shared by all nodes, That is, all the computers are attached to the same communication line. When a particular computer wants to send a message to another computer, it appends the destination address to the message and checks whether the communication line is free. As soon as the line becomes free, it broadcasts the message on the line. As the message travels on the line, each computer checks whether it is addressed to it. The message is picked up by the addressee computers, which sends an acknowledgement to the source computer and frees the line. This type of network is also known as ‘multipoint’ or’ broadcasting’ network. It is appropriate for use in a local area network where a high-speed communication channel is used and computers are confined to a small area. It is also appropriate when satellite communication is used as many computers at a number of geographical locations may share one satellite channel.

ADAVANTAGES:-

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Single communication line shared by all nodes

1. The main advantage of a multi-access bus network is reduction in physical lines.2. The failure of a computer in the network does not affect the network functioning for

other computers.3. Addition of new computers to the network is easy.

DISADVANTAGES:-

1. All computers in the network must have good communication and decision-making capability.

2. If the communication line fails, the entire system breaks down.

HYBRID NETWORK:-

Different network configurations have their own advantages and limitations. Hence in reality a pure star or ring or completely connected network is rarely used. Instead, an organization will use some sort of hybrid network, which is a combination of two or more different network topologies. The exact configuration of the network depends on the needs and the overall organization structure of the company involved. In some cases, the hybrid network may components of star, ring, and completely connected networks. A typical hybrid network of this type is shown in the following figure.

Q. PACKET TRANSMISSION?Ans. A message is a logical unit of information and can be of any length. In packet transmission a message is split up to ‘packets’ of a fixed size (of the order of one or few thousand bits). Besides the block of data (part of a message) to be sent, a packet has a header that contains the destination and source addresses, control information, message number, number of current and last packet, synchronization bits, acknowledgement and error checking bytes, etc. Like message switching the packets may be routed from the sender node to the destination node either by store-and-forward method or by broadcast method. In the store and forward method, the packets are stored temporarily at the

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intermediate nodes for error recovery purchases and are routed to the next node based on an available free channel. The actual path taken by the packet to its destination is dynamic as the path is established as its travels along. Thus, it s possible that different packets of the same message can be routed across different paths leading to the same destination upon line availability and congestion.

ADVANTAGES:-

1. Unlike messages, packets are of small and fixed size. Hence the storage requirement for buffering the packets at intermediate nodes is minimal.

2. Since the routing is done on packet basis the intermediate nodes do not have to wait for the either message, hence the transmission is very fast.

3. The method is fast enough for interactive/real time applications.4. It is most suitable for ‘bur sty’ computer-to-computer communication and is widely

used in wide area networks.

DISADVANTAGES:-

1. Due tot the need to buffer each packet at every intermediate node and to reassemble the packets at the destination node, the overhead incurred per packet is large.

2. There is no guarantee of how long it takes a message to go from its source node to its destination node because the time taken for each packet depends on the route chosen for that packet, along with the volume of data being transferred that route.

Q. LONG DISTANCE COMMUNICATION?

Ans. If data is sent over long distance s, the analog signal can become weak and distorted. To avoid this, amplifiers are used. An amplifier used in a communication system is similar to the amplifier used in a home stereo system-it strengthens or amplifies a weak signal. Amplifiers are typically placed alone communication lines between modems.Today, signals are also sent in digital mode. In this case modems are not neede. When digital mode of transmission is used over long distances, a repeater is used to receive and then transmit the signal. Like an amplifier, the purpose of a repeater is to strengthen a weak digital signal over long distance.

Digital transmission of digital data is preferred to analog transmission of digital data due to the following reasons:-

1. Lower cost.2. No modems required.3. Higher transmission speed possible, and4. Lower error rate.

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Q. APPLICATIONS OF NETWORK?

Ans. Communication-Using a computer connected to the Internet, there are a variety of ways for people to communicate with one another. People have an insatiable desire to communicate (letters, postcards, telegram, radio, TV, telephone, answering machine, fax, etc.). A computer connected to the Internet offers several more options.

ELECTRONIC MAIL-

1. Like a postcard or letter.2. Several technical differences. Sender writes on his or her computer and recipient receives message on a different

computer. Usually mail is delivered more quickly then postal mail. The same message can be sent one or more people.

3. Several cultural differences. E-mail messages can be very short. Often a dialog between two or more people. Can quote previous message.

4. Cheapest source of communication. E-mail messages can be send any where in the world at same price. Unlike Fax, you don’t have to wait for the receiver to receive the message. There are various sits offering free email services such as www.yahoo.com

or www.hotmail.com.

Browsing:-

The Internet good at storing large amounts of data allows individuals to browse richely cross-references texts and follow trails of interconnected information as one does in en encyclopendia-1. The heart of the Internet is browsing.

We find a lot of cross- referenced text; hence it is easy to shift between pages. Browsing is accomplished by following links, the connections between related

information.

2.A number of different Internet facilities allows browsing including the Web, gopher, and wais.3. You need Internet browser programs on your computer to browser on Internet such

as Netscape Navigator, Microsoft Internet Explorer etc.4. We find material on all areas such as Research, Education, Health, Business, Stock

etc.

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WORLD WIDE WEB:-

1.The web is a random collection of information written and cross-referenced by the masses. a) Information is stored on computers around the world that are connected to the Internet.

2.Browsers are software products that provide a means of viewing the information on the Web.

3. A web site is a collection of related pages.4. A home page is a starting point for browsing a web site.5. A URL is the electronic equivalent of a call number on the spine of a library book.

It indicates the location of a page on the web.

SEARCHING:-With so much information, it’s hard to find specific information by browsing. The Internet contains indexes and other tools to help people search. These are called search engines.

INTEGRATING:-

Materials on the Internet can be integrated into teaching, learning and professional activities. Students can research almost any from A-Z. Teachers can design lessons based on material published on the Internet.

CREATING:-

People can make their own websites to share the data with the rest of the world. Companies can make their corporate sites to market themselves on Internet, Scientists can put their research work, teachers can put lessons, writers can put their articles etc.

Q. DATABASE?

Ans. Databases and database technology are having a major impact on the growing use of computers. It is fair to say that databases play a critical role in almost all areas where computer are used, including business, engineering, medicine, law, education, and library to name a few .A database is a collection of related data. By data we mean known facts that can be recorded and that have implicit meaning. For Ex. Consider the names, telephone numbers, and addresses of the people you know. You may have recorded this data in an indexed address book, or you may have stored it on a diskettes, using a personal computer and software such as DBASE IV or V, Microsoft ACCESS, or EXCEL. This is a collection of related data with an implicit meaning and hence is a database.A database has the following properties:-

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1. A database represents some aspect of the real world, sometimes called the mini-world or the Universe of Discourse (UoD). Changes to the min-world are reflected in the database.

2. A database is a logically coherent collection of data with some natural meaning. 3. A database is designed, built, and populated with data for a specific purpose. It has

an intended group of uses and some preconceived applications in which these users are interested.

1. The data in the database is stored in the table format.

Field NameData item

File

S.no-1, emp.Code-05, Emp.Name-ABC and Address 56/6,fbd is called a record.

Field Name-: The name of each data item is known as field name e.g Address, Emp. Name etc.

Record:- Record is a collection of related data

Data Item:- Data item or field is a set of character.

When Not to Use a DBMS-

1. High initial investment in hardware, software, and training.2. Generally that a DBMS provides for defining data.3. Overhead for providing security, recovery, and integrity functions.

DATABASE OBJECTIVES:-

1. Compactness-: If we use database, then all records are stored in computer and only one place (on e file). So we have no need for paper files.

2. The data can be shared:- Sharing means not only that existing applications can share the data in the database, but also that new applications can be developed to operate against that same data. In other words, it might possible to satisfy the data requirements of new applications without having to add any new data to the database.

S.no. Emp. Code Emp.Name Address1 05 ABC 56/6, Fbd2 06 XYZ 96/8, Fbd

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3. Redundancy can be reduced:- In non database system each application has its own private files. This fact can often lead to considerable redundancy in stored data, with resultant waste in storage space. For example, a personnel application and an education records application might both own a file that includes department information for employees. But if we maintain all files in a database then data administrator allows only few members to make changes in the files, he also aware about this. His database should be aware of it, if it exists, and should assume responsibility for “ propagating updates”.

4. Inconsistency can be avoided:- This is really a corollary of the previous point. Suppose a given fact about the real world-say the fact that employee E3 works in department D8- is represented by two distinct entries in the database. Suppose also that the DBMS is not aware of this duplication. Then there will necessarily be occasions on which the two entries will not agree. Namely, when one of the two has been update and the other not. At such times the database is said to be inconsistent. Cleary, a database that is in an inconsistent state is capable of supplying incorrect or contradictory information to its users. Of course, if the given fact is represented by a single entry (i.e. if the redundancy is not removed but is controlled (by making it known to the DBMS), then the DBMS can guarantee that the database is never inconsistent as seen by the user, by ensuring that any change made to either of the two entries is automatically applied to the other one as well. This process is known as propagating updates.

5. Transaction Support can be provided:- A transaction is a logical unit of work, typically involving several database operations (in particular, several update operations). The standard example involve the transfer of a cash amount from one account A to another account B. Cleary two updates are account B. If the user has stated that the two updates are part of the same transaction, then the system can effectively guarantee that either both of them are done or either is- even if, e.g. the system fails (say because of a power outage) halfway through the process.

6. Integrity can be maintained:- The problem of integrity is the problem of ensuring that the data in the database is correct. Inconsistency between two entries that purpose to represent the same “fact” is an example of lack of integrity, of course, this particular problem can arise only if redundancy exists in the stored data. Even if there is no redundancy the database might still contain incorrect information. Centralized control of the database can help in avoiding such problems- insofar as permitting the data administrator to define, and the DBA to implement can avoid them.

7. Easy to access :- DBMS allows convenient and efficient retrieval of data. But in a conventional file processing system, any retrieval request can be served until the programmer has designed its application program. Thus, DBMS provides a more responsive data retrieval system.

ENTITIES:-

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A record that can be uniquely identified is called an entity. Entity is an object that exits and is differ, from all other objects, e.g. a student Sahil with roll no, “2254” is an entity. Each entity has some set of properties.

ATTRIBUTS:-Attributes are the properties or characteristics of an entity e.g. an entity of entity set ‘student’ may have attributes- Sname, Rollno, trade and semester. The values of these attributes identify one entity from others.

SCHEMA:-

Database schema refers to the design of the database. Schema is of a part of the database. Schema is a logical database description and is drawn as a chart of the types of data that are used. It gives the names of the entities and attributes and specifies the relationships (one-to-one, one-to-many, many-to-many) between them. I t is a framework into which the values of the data items can be fitted. The schema will remain same if time to time value changes.

SUBSCHEMA-

The term sub schema refers to the same view, but for the data-item types and record types which a particular user uses in a particular application. Therefore, many different sub-schemas can be derived from one schema.

UNIT-IV

Internetworking:-

Ans.

Interconnecting of two or more networks to form a single network is called internetworking, and the resulting network is called an inter-network. Therefore, a WAN of multiple LAN’s is an inter-network.Inter-networks are often heterogeneous network composed of several network segments that any differ in topology and protocol. For example, an inter-network may have multiple LAN’s some of which may have multi-access bus topology while others may have ring topology; some of these LAN’s may be using Ethernet technology while others may be using Token Ring technology; and some segments of the network may be using the IP suite while others may be using IBM’s SNA (System Network Architecture) protocol suite. Inter-networking allows these relatively unrelated networks to evolve into a single working system. That is, the goal of inter-networking is to hide the details of different physical networks, so that the resulting inter-network functions as a single coordinated unit. Internetworking two networks having the same topology and protocol is because the two networks an easily communicate with each other. Internetworking two dissimilar networks that have different topologies and protocols requires an inter-networking scheme that

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provides some common point of reference for the two networks to communicate with each other. That point of reference might be a high-level protocol common to the two networks, a device that allows inter-connection of different topologies with different physical and electrical characteristics, or a protocol that allows operating environment differences to be ignored. The most commonly used approach is to make use of common high-level protocols for moving data between common layers on a communications model such as the OSI or the IP suits. Inter-networking tools, such as bridges, routers, brouters, and gateways, make extensive use of this approach.

INTERNET PROTOCOL ADDRESS:-

Ans.

An Internet (IP) address is a numeric identifier assigned to each machine on an IP network. It designates the location of the device it is assigned to on the network. An IP address is made up of 32 bitts of information. These bits are divided into four sections containing one byte (8 bits each). These sections are referred to as octets. There are three methods for depicting an IP address.

1. Dotted-decimal as in 130.57.30.562. Binary, as in 10000010.00111001.0011110.001110003. Hexadecimal, as in 8239 IE 38.

All the tree examples given above represent the same IP address. The 32-bit IP addressing is a two-level hierarchical addressing scheme. The first part is designed as network address and the other part of the address is designed as a node address. The network address uniquely identifies each network. Every machine on the same network shares that network address as a part of its IP address. In the IP address 130.57.30.56, of our example, the 130.57 is the network address.The node address is assigned to, and uniquely identifies, each machine on the network. This part of the address must be unique because it identifies a particular machine-an individual, as opposed to a network, which is a group. The number can also be referred to as a host address. In the sample IP address 130.57.30.56, the 30.56 is the node address.(AN IP ADDRESS IS A SOFTWARE ADDRESS, NOT A HARDWARE ADDRESS, WHICH IS A HARD-CODE IN THE MACHINE OR NETWORK INTERFACE CARD.)

INTERNET APPLICATIONS:-

Ans.

1. To exchange electronic mail with friends all over the globe for a very small price.2. To participate in-group discussion on topics of interest, through public news groups.

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3. To find educational tools, universities around the world, bookstores, and libraries are sharing online information.

4. Commercial electronic storefronts are growing in number in the USA and Europe. One can order different products over the Internet.

5. In the case of business one can get technical support for products one is using. One can publish information such as technical or marketing literature.

6. Because the Internet is electronic, one can make changes to reflect late breaking news that would be impossible for printed publications. Change becomes easier, updates are simpler and information is instant.

7. The Internet has become the first global venue for publishing information. This network has enough users now and it is benefiting from the positive feedback loop; the more users it gets, the more control it gets; and the more content it gets, the more users it gets.

WWW PAGES AND BROWSING?

Ans.

The World Wide Web, or “the Web”, is an Internet based global information system that makes available multimedia information from over 4 million computers around the world. The Web offers video, interactive multimedia and lives audio, in addition to more basic data types, such as text documents and still photographs.WWW is a huge collection of hypertext pages on the Internet. The concept of WWW was developed in Switzerland at the European Particle Research Centre (CERN) in the year 1989.

Features of WWW:-

The Web is one of the most flexible and exciting tools for surfing the Internet. Using Mosaic viewer, the WWW made it possible for a site to set up a number of pages of information containing text, picture, sound and even video with embedded links to other pages. By clinking on a link, the user is moved to the page pointed to by that link. For Example, a company can have a home page with entries pointing to other pages for product information, price lists, sales, technical support, communication with employees, stockholder information and so on.

WWW Browsers:-

A Web browser is a program you use to view pages on and navigate the World Wide Web. Browsers are sometimes referred to as Web clients or other fancy names (Internet navigation tools”), but Web browser is the most common term.

A wide range of Web browsers is available for every type of systems you can imagine, including graphical-user-interface., and the text-only for dial-up UNIX connections. Most

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browsers are freeware. Usually, all you have to do is to get a browser-downloaded form the Internet. For example, Internet Explorer 5.0 version comes free as part of Window 98.Popular Web-Browsers are-

1. ncSA Mosaic2. Netscape Navigator3. Lynx4. Microsoft Internet Explorer.

A web Browser does the following two types of services -

1. Given a URL address, it should be able to access that information. For hypertext Web documents, this means that browser must be able to communicate with the Web server using the HTTP protocol.

2. Because the Web can also manage information contained on FTP and Gopher servers, in Usenet news communicate with those servers or protocols as well.

Different browsers may format and display the same file differently, depending on the capabilities of the hardware and the default layout options for the browser itself.

SECURITY OF THE INTERNET:-Ans.Overview of internet security threats :-

1. Identity Interception:- The identity of one or more of the users involved in a communication is observed for misuse.

2. Pretending:- The pretence by a user to be a different user in order to gain access to information or to acquire additional privileges.

3. Reply:- The recording and subsequent replay of a communication at some later date.

4. Data interception:- The observation of user data during a communication by an unauthorized user.

5. Manipulation:- The replacement, insertion, deletion of user data during a communication by an unauthorized user.

6. Rejection:- The denial by the a user of having participated in part or all of a communication.

FIREWALLS:- Every time a corporation connects its internal computer network or LAN to the Internet, it faces potential danger regarding security. Due to the Internet’s openness, every corporate network connected to it is vulnerable to attack. Crackers on the Internet could theoretically breaks into the corporate network and do harm in a number of the following ways:-

1. They could steal or damage important data.2. Damage individual computer or the entire network.

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3. Use the corporate computer’s resources or use the corporate network and resources as a way of posing as a corporate employee.

The solution for all these problems and many more is to build ‘firewalls’ to protect its network. These firewalls allow anyone on the corporate network to access the Internet bur they stop crackers, hackers or others on the Internet from gaining access to the corporate network and causing damage.

(Firewalls are hardware and software combinations that are built using routers, servers and a variety of software. They sit at the most vulnerable point between a corporate network and the Internet and they can be as simple or complex as system administrators want to build them.)

Benefits of Using a Firewall:-

1. Protection from services that are inherently more prone to attacks.2. Access to host in the network can be strictly controlled.3. Security is concentrated on a single firewall system. This leads to better

implementation of authentication procedures.4. Logging and statistics of network use and misuse.5. Policy enforcement.

Types of firewalls:-

1. Packet filtering.2. Application gateways.

A firewall basically performs two important functions:-

1. Gate-keeping:- Firewall acts as a gatekeeper between the company’s internal network and the outside network. It examines the location from which the data enters your system and then decides, based on your instructions, whether or not to allow that information.

2. Monitoring by Firewall:- in addition to Gate-keeping , the firewall also monitors information. Monitoring is one of the most important aspects of firewall design. Monitoring functions include logging of all system activities and generation of reports for system administration. Monitoring can be active or passive. In active monitoring, a firewall notifies a manager whenever an incident occurs. The firewall product, Smart wall, alerts the administrator via e-mail or pager about suspicious on line activity. In passive monitoring, a firewall logs a record of each incident in a file or a disk. Then a manager can analyze the log periodically to determine whether attempts to access the organization have increased over time.

E-COMMERCE:-

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E-commerce is any form of business exchange or transaction in which the parties interact electronically. Firms such as Dell (computers), Varsity-books (textbooks) and PC Flowers and Gifts are engaged in e-commerce transactions.

Advantages:-

Convenience:- Cyber-stores never close their doors. In a recent survey conducted by Forrester Research, active Web shoppers rated convenience the number one reason to shop on-line. Savings:- Businesses such as Dell Computer Corporations and General Electric are using the Internet to link directly to suppliers, factories, distributors, and customers. They are wringing waste out of the system and passing on saving to customers. On-line retailers such as Amazon.com reap the advantage of negative operating cycle: Anazon receives cash from credit-card companies just a day after customers place an order. Then it can hold on to the money for 46 days until pays suppliers, the book distributors and publishers. Customers stand to benefit most of all, because they can scour the Web to search for the lowest price. There are even sits such as Compare.Net, which offers a free on-line buyer’s guide that allows users to compare features of 10,000 products.Selection: The World’s the limit for the Web. Unrestrained by physical boundaries, cyber-stores can offer an almost unlimited selection. Go to the CD-Now and Virtual Vineyards sites and then compare the selection with the offerings of the local music or liquor store. Collapsed geographic boundaries also open up market all over the world and make upstarts indistinguishable from established companies.Personalization:- With the help of computer’s slice and dice information captured on the Web, businesses can personalize their sales pitches and even their products. CNN’s Web site enables individuals to create personal profiles of their news interests and updates them every 15 minutes.Information:- Although it’s true that the human interface is missing, the Web makes up for it tenfold with the amount of information available. Good sites provide more information in more useful forms then the most solicitous salesclerk does.

Application of E-commerce:-

1.Save transaction costs for both buyers and suppliers:- A Web-powered purchasing program eliminates the paper chase associated with traditional requisition and ordering procedures. At National Semiconductor, the $75 to $250 cost of processing each paper-based requisition has been cut to just $3 per electronic order.

2.Reduce time between order and delivery:- Time saving are particularly dramatic for companies with many overseas suppliers. Adaptec Inc., a leading supplier of computer storage, used an extranet to tie all of its Taiwanes chip suppliers together in a kind of virtual keiretsu. Now messages from Adaptec flow in seconds from its headquarters to its Asian partners and adaptec has reduced the time between the order and delivery of its chips from as long as 16week to just 55 days-the same turnaround time for companies that build their own chips.

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Consolidate purchasing systems:- One key motivation for on-line purchasing has been a desire to get rid of redundancy. 3.Cut jobs for millions of clerks and order processors:- All these saving and efficiencies don’t come without a price. National Semiconductor reduced its purchasing staff by more then half when it took its purchasing activities on-line. On the other hand, for many purchasing professionals, going on-line means reducing drudgery and paperwork and spending more time managing inventory and working creatively with suppliers.4. More intimate (close) relationships between partners and buyers:- Robert Mondavi Corporation puts satellite images of its vineyards out over the extranet so that its independent growers can pinpoint potential vineyard problems and improve the grapes Mondavi purchase from them.5.Level the playing field between large and small suppliers:- By using the internet’s technology to establish secure, standing information links between companies, extranets have helped firms do business with smaller suppliers. Currently most large manufacturers use electronic data interchange (EDI) to order suppliers, because it provides a secure means of coding and exchanging standardized business forms. Moving business-to-business commerce onto the Web also levels the playing field between local and foreign suppliers because purchases can source materials from suppliers all over the globe for no additional transaction cost.6.Create potential security disasters:- More then 80 percent of companies say security is the leading barrier to expanding electronic links with customers and partners. Although e-mail and home banking transactions can be protected through basic encryption, the secure environment that businesses need to carry out many confidential interactions still does not exist. Companies are creating their own defensive strategies for keeping hackers at bay. The companies go further by sending its own security engineers to examine a partner’s defenses and hold the partner liable for any security breach that originates from its computer.

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Basic computer organization

Even through the size, shape, performance, reliability, and costs of computers have been changing over the year; the basic logical structure (based on stored program concept) as by Von Neumann has not changed. No matter what shape and size of computer we are talking about all computer systems perform the following five basic operations for converting raw input data into information useful to their users:

1. Inputting . The process of entering data and instructions into the computer system.

2. Storing . Saving data and instructions so that they are available for initial or for additional processing as and when required.

3. Processing . Performing arithmetic operations (add, subtract, multiply, divide, etc) or logical operations (comparisons like equal to, less then, greater than, etc) on data in order to convert them into useful information.

4. Output . The process of producing useful information or results for the user, such as a printed report or visual display.

5. Controlling . Directing the manner and sequence in which all of the above operations are performed.

The goal of this chapter is to familiarize you with computer system unites that performs these functions. This chapter will provide you with overview computer systems as computer system architects view them.

The internal architectural design of computers offers from one system model to another. However, the basic organization remains same for all computer system. A block diagram of the basic computer organization is. In the figure, the solid lines are used to indicate the flow of instructions and data, and the dotted lines represent the control exercised by the control unit. It displays the five major building blocks, functional units of a digital computer system. The five units correspond to the five basic operations performed by all computer systems. The function of each these units are described below.

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Program information (Result)And Data

Indicates Flow of Instructions And Data Indicates The control Exercised by

the Control

unit. Control Processing Unit (CPU)

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Secondary

Storage

Primary

Storage

InputUnit

OutputU

nit

ControlUnit

Arithmetic Logic Unit

INPUT UNIT:Data and instructions must enter the computer system before any computation can be performed on the supplied data.The input unit that links the external environment with the computer system performs the task. Data can entered in the computer through Keyboard or Scanner (it is a type of input device). The data or instructions are accepted in the computer in binary codes, units called Input Interfaces accomplish this transformation.

In short, the following functions are performed by an input unit:

1. It accepts (or reads) the list of instructions and the data from the outside world.

2. It converts these instructions and data in computer acceptable form.3. It supplies the converted instructions and data to the computer system for

further processing.

OUTPUT UNIT:The job of an out put unit is just the reverse of that of an input unit. It supplies the

information as a result of data processing to the outside world. As computer works in the binary code, the results produced are also in the binary form. Hence, before supplying the result to the outside world, it must be converted in the human acceptable (readable) form. This task is accomplished by units called output Interfaces.

In short the output unit performs the following functions:

1. Ist accepts the result produced by the computer, which are in the coded form and hence cannot be easily understood by us.

2. It converts these coded to the human acceptable (readable) form.3. It supplies the converted results to the outside world.

STORAGE UNIT:The data and instructions that are entered into the computer system through input units have to be stored inside the computer before the actual processing starts. This unit provides space for storing data and instructions, space for intermediate results.

In short, the specific functions of storage unit are to hold (store):1. All data to be processed and the instructions required for processing

(received from input device).2. Intermediate results for processing.3. Final result of processing before these results are released to an output

device.

The storage unit of all is comprised by the following too type of storage:

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1. Primary storage. The primary storage, also known as main memory, is used to hold peaces of program instruction and data, intermediate result of the processing of the job(s)that the computer system is currently working on. These peaces of the information are represented electronically in the main memory chip’s circuitry, and while it remains in the main memory, the central processing unit can access it directly at a fast speed. The primary storage has a limited storage capacity because it is very expensive. The primary of a modern computer system is made of semiconductors device.

2. Secondary Storage . The secondary storage, also known as auxiliary storage, is used to take care of the limitations of the primary storage. That is, it is used to supplement the limit storage capacity and the volatile characteristic of a primary storage. This is a because secondary is much cheaper then primary storage and it can retain information even when the computer

system is switched off or reset. The secondary storage is normally used to hold the program instruction, data and information of those jobs on which the computer system is not working on currently , but needs to hold them for processing at a later time. The most commonly used secondary storage medium is the magnetic disk.

ARITHMATIC LOGIC UNIT:

The arithmetic logic unit (ALU) of the computer system is the place where the actual execution of the of the instruction tasks place during the processing. To be more precise, calculations are performed and all comparisons are made in the ALU. The data and instructions, stored in the primary storage prior to processing are transferred as and when needed to the ALU where processing takes place. No processing is done in the primary storage unit. Intermediate results generated in the ALU are temporarily transferred back to the primary storage until needed at a later time. Data may thus move from storage to ALU and back again to storage many times before the processing is over. After the completion of processing the final result which r stored in the storage unit r released to an output device.

The type and number of arithmetic and logic operations that a computer can perform is determined by the engineering design of the ALU. However, almost all ALU’ s are designed to perform the four basic arithmetic operation (add, subtract, multiply, and divide), and logic operations or comparisons such as less than, equal to, and greater than.

CONTROL UNIT:-

How does the input device know that it is time for it to feed data into the storage unit? How does the ALU know what should be done with the data once they are received? And how it is that only the final results are sent to the output device and not the intermediate results? All this is possible because of the control unit of the computer system. By selecting, interpreting, and seeing to the execution of the program instructions, the control unit is able to maintain order and direct the operation of the entire system. Although, it does not perform any actual processing on the data, the control unit acts as a central nervous system

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for the other component of the computer system. . It obtains instructions from the program stored in the memory, iterates the instructions, and issues signals that cause other units of the system to execute them.

CENTRAL PROCESSING UNIT: The control unit and the arithmetic logic unit of the computer system is jointly is known as central processing unit (CPU). The CPU is the brain of any computer system. In a human body, the brain takes all major decision and the other parts of the body function as directed by the brain. Similarly, in the computer system, all major calculation comprehensions are made inside the C.P.U and the CPU is also responsible for activating and controlling the operations of other units of a computer system.

THE SYSTEM CONCEPT:

You might have observed by now that we have been referring to a computer as a system (computer system).What we be the reason behind this? To know the answer let us first consider the definition of a system.

A system system is a group of integrated parts that have the common purpose of achieving some objective(s). So, the following three characteristics are key to a system:

1. A system has more then one elements.2. All the elements of the system are logically related.3. All the elements of a system are controlled in such a way that the system goal

is achieved.

Since a computer is made up of integrated components (input, output, storage and CPU) that work together to perform the steps called for in the program being executed, it is a system. The input and output units cannot function until they receive signals from the CPU. Similarly, the storage unit or the CPU is of on use. So the usefulness of each unit depends on other units and can be realized only when all units are put together (integrated) to form a system.

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