Computer Science (BBA) 1st Semester

UNIT I Introduction and Evolution of Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem. An important class of computer operations on some computing platforms is the accepting of input from human operators and the output of results formatted for human consumption. The interface between the computer and the human operator is known as the user interface. Conventionally a computer consists of some form of memory, at least one element that carries out arithmetic and logic operations, and a sequencing and control unit that can change the order of operations based on the information that is stored. Peripheral devices allow information to be entered from an external source, and allow the results of operations to be sent out. General Functions of Computer Computer is an advanced electronic device that takes raw data as input from the user and processes these data under the control of set of instructions (called program) and gives the result (output) and saves output for the future use. It can process

Input (Data): both numerical and non-numerical (arithmetic and logical) calculations. Input is the raw information entered into a computer from the input devices. It is the collection of letters, numbers, images etc. Data Data can be defined as a representation of facts, concepts or instructions in a formalized manner which should be suitable for communication, interpretation, or processing by human or electronic machine. Data is represented with the help of characters like alphabets (A-Z,a-z), digits (0-9) or special characters(+,-,/,*,<,>,= etc.) or symbols. For example: Ram Thapa Paush month salary 15000 bonus 2000 total 17000.

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Information Information is organized or classified data which has some meaningful values for the receiver. Information is the processed data on which decisions and actions are based. For the decision to be meaningful, the processed data must qualify for the following characteristics: Timely - Information should be available when required. Accuracy - Information should be accurate. Completeness - Information should be complete. Example: Name Month Salary Bonus Total Rama Thapa Paush 15000 2000 17000 Process: Process is the operation of data as per given instruction. It is totally internal process of the computer system. Output: Output is the processed data given by computer after data processing. Output is also called as Result. We can save these results in the storage devices for the future use. Storage: Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data. Data storage is a core function and fundamental component of computers. Computer System All of the components of a computer system can be summarized with the simple equations. COMPUTER SYSTEM = HARDWARE + SOFTWARE+ USER • Hardware = Internal Devices + Peripheral Devices The hardware are the parts of the computer itself including the Central Processing Unit (CPU) and related microchips and micro-circuitry, keyboards, monitors, case and drives (hard, CD, DVD, floppy, optical, tape, etc...). Other extra parts called peripheral components or devices include mouse, printers, modems, scanners, digital cameras and cards (sound, color, video) etc... Together they are often referred to as a personal computer. All physical parts of the computer (or everything that we can touch) are known as Hardware. • Software = Programs The software is the information that the computer uses to get the job done. Software needs to be accessed before it can be used. There are many terms used for the process of accessing software including running, executing, starting up, opening, and others. Computer programs allow users to complete tasks. A program can also be referred to as an application and the two words are used interchangeably. Software gives "intelligence" to the computer. • USER = Person, who operates computer. A user is an agent, either a human agent (end-user) or software agent, who uses a computer or network service. Users are also widely characterized as the class of people that use a system without complete technical expertise required to understand the system fully. Such users are also divided into users and power users. Both are terms of degradation but the latter connotes a "know-it-all" attitude. In projects in which the actor of the system is another system or a software agent, it is quite possible that there is no end- user for the system. In this case, the end-users for the system would be indirect end-users.

CHARACTERISTICS OF COMPUTER Speed, accuracy, diligence, storage capability and versatility are some of the key characteristics of a computer. A brief overview of these characteristics are— Speed The computer can process data very fast, at the rate of millions of instructions per second. Some calculations that would have taken hours and days to complete otherwise, can be completed in a few seconds using the computer. For example, calculation and generation of salary slips of thousands of employees of an organization, weather forecasting that requires analysis of a large amount of data related to temperature, pressure and humidity of various places, etc. Accuracy Computer provides a high degree of accuracy. For example, the computer can accurately give the result of division of any two numbers up to 10 decimal places. 2

Diligence When used for a longer period of time, the computer does not get tired or fatigued. It can perform long and complex calculations with the same speed and accuracy from the start till the end. Storage Capability Large volumes of data and information can be stored in the computer and also retrieved whenever required. A limited amount of data can be stored, temporarily, in the primary memory. Secondary storage devices like floppy disk and compact disk can store a large amount of data permanently. Versatility Computer is versatile in nature. It can perform different types of tasks with the same ease. At one moment you can use the computer to prepare a letter document and in the next moment you may play music or print a document. Automatic: - Once the instruction to do any work is given to the computer, the computer does its work automatically by itself. Reliability: - Since computer can do its work very fast, without making any mistake and without taking rest and is able to store data for future use, it is a very reliable or trustworthy machine.

Limitations of Computer: Computers have several limitations too. Computer can only perform tasks that it has been programmed to do. Computer cannot do any work without instructions from the user. It executes instructions as specifi ed by the user

and does not take its own decisions. (i) Computers can’t think: Computers cannot think and they can’t do any job unless they are first programmed with specific instructions for same. They work as per stored instructions. Algorithms are designed by humans to make a computer perform a special task. This is also called artificial intelligence. (ii) Computers can’t decide: Computers are incapable of decision making as they do not possess the essential elements necessary to take a decision i.e. knowledge, information, wisdom, intelligence and the ability to judge. (iii) Computers can’t express their Ideas: In any type of research ideas plays a vital role. In this context, computers can’t express their ideas. (iv) Computers can’t implement: Though computers are helpful in storage of data and can contain the contents of encyclopedias even, but only humans can decide and implement the policies. (v) No learning power Computer has no learning power. Once you give instructions to a computer how to perform a task, the very task is cannot perform if you do not give it any instructions for the next time. For example, when you are taught how to solve a problem and it same type of problem is given to you to solve, then you can do it because you have learned how to solve the problem.

History of computer The history of computer science began long before the modem discipline of computer science that emerged in the twentieth century, and implied at in the centuries prior. The progression, from mechanical inventions and mathematical theories towards the modern concepts and machines, formed a major academic field and the basis of a massive worldwide industry. Mechanical computers: A mechanical computer is built from mechanical components such as levers and gears, rather than electronic components. The most common examples are adding machines and mechanical counters, which use the turning of gears to increment output displays. More complex examples can carry out multiplication and division, and even differential analysis.

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Abacus

The abacus, also called a counting frame, is a calculating tool used primarily in parts of Asia for performing arithmetic processes. Today, abaci are often constructed as a bamboo frame with beads sliding on wires, but originally they were beans or stones moved in grooves in sand or on tablets of wood, stone, or metal. The abacus was in use centuries before the adoption of the written modern numeral system and is still widely used by merchants, traders and clerks in Asia, Africa, and elsewhere. The user of an abacus is called an abacist. Napier’s bones

Napier's bones is created by John Napier for calculation of products and quotients of numbers that was based on Arab mathematics and lattice multiplication. The Napier's bones consists of a board with a rim; the user places Napier's rods in the rim to conduct multiplication or division. The board's left edge is divided into 9 squares, holding the numbers 1 to 9. The Napier's rods consist of strips of wood, metal or heavy cardboard. Napier's bones are three dimensional, square in cross section, with four different rods engraved on each one. A set of such bones might be enclosed in a convenient carrying case. A rod's surface comprises 9 squares, and each square, except for the top one, comprises two halves divided by a diagonal line. The first square of each rod holds a single digit, and the other squares hold this number's double, triple, quadruple, quintuple, and so on until the last square contains nine times the number in the top square. The digits of each product are written one to each side of the diagonal; numbers less than 10 occupy the lower triangle, with a zero in the top half. A set consists of 10 rods corresponding to digits 0 to 9. The rod 0, although it may look unnecessary, is obviously still needed for multipliers or multiplicands having 0 in them. 4

Slide rule

The slide rule is a mechanical computer. The slide rule is used primarily for multiplication and division, and also for functions such as roots, logarithms and trigonometry, but is not normally used for addition or subtraction. Slide rules come in a diverse range of styles and generally appear in a linear or circular form with a standardized set of markings (scales) essential to performing mathematical computations. Slide rules manufactured for specialized fields such as aviation or finance typically feature additional scales that aid in calculations common to that field. William Oughtred and others developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier. Before the advent of the pocket calculator, it was the most commonly used calculation tool in science and engineering. The use of slide rules continued to grow through the 1950s and 1960s even as digital computing devices were being gradually introduced; but around 1974 the electronic scientific calculator made it largely obsolete and most suppliers left the business. Pascal's calculator

Blaise Pascal invented the mechanical calculator in 1642. He conceived the idea while trying to help his father who had been assigned the task of reorganizing the tax revenues of the French province of Haute-Normandie ; first called Arithmetic Machine, Pascal's Calculator and later Pascaline, it could add and subtract directly and multiply and divide by repetition. Pascal went through 50 prototypes before presenting his first machine to the public in 1645. He dedicated it to Pierre Seguier, the chancellor of France at the time. He built around twenty more machines during the next decade, often improving on his original design. Nine machines have survived the centuries, most of them being on display in European museums. In 1649 a royal privilege, signed by Louis XIV of France, gave him the exclusivity of the design and manufacturing of calculating machines in France.

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Stepped Reckoner

The Step Reckoner (or Stepped Reckoner) was a mechanical calculator invented by German mathematician Gottfried Wilhelm Leibniz around 1673 and completed in 1694. The name comes from the translation of the German term for its operating mechanism; staffelwalze meaning 'stepped drum'. It was the first calculator that could perform all four arithmetic operations: addition, subtraction, multiplication and division. Its complex precision gear work, however, was somewhat beyond the fabrication technology of the time; mechanical problems, in addition to a design flaw in the carry mechanism, prevented the machines from working reliably.

Jacquard loom The Jacquard loom is a mechanical loom, invented by Joseph Marie Jacquard in 1801, that simplifies the process of manufacturing textiles with complex patterns such as brocade, damask and matelasse. The loom is controlled by punched cards with punched holes, each row of which corresponds to one row of the design. Multiple rows of holes are punched on each card and the many cards that compose the design of the textile are strung together in order. It is based on earlier inventions by the Frenchmen Basile Bouchon (1725), Jean Baptiste Falcon (1728) and Jacques Vaucanson (1740).

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Charles Babbage's Difference engine A difference engine is an automatic, mechanical calculator designed to tabulate polynomial functions. The name derives from the method of divided differences, a way to interpolate or tabulate functions by using a small set of polynomial coefficients. Both logarithmic and trigonometric functions, functions commonly used by both navigators and scientists, can be approximated by polynomials, so a difference engine can compute many useful sets of numbers. The historical difficulty in producing error free tables by teams of mathematicians and human "computers" spurred Charles Babbage's desire to build a mechanism to automate the process.

Analytical Engine

The Analytical Engine was a proposed mechanical general-purpose computer designed by English mathematician Charles Babbage. It was first described in 1837 as the successor to Babbage's difference engine, a design for a mechanical calculator. The Analytical Engine incorporated an arithmetical unit, control flow in the form of conditional branching and loops, and integrated memory, making it the first Turing-complete design for a general-purpose computer.

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Charles Babbage (1791-1871) the Father of Computers Charles Babbage is recognized today as the Father of Computers because his impressive designs for the Difference Engine and Analytical Engine foreshadowed the invention of the modern electronic digital computer. While Babbage's machines were mechanical and unwieldy, their basic architecture was similar to a modern computer. The data and program memory were separated, operation was instruction-based, the control unit could make conditional jumps, and the machine had a separate I/O unit. Lady Augusta Ada Countess of Lovelace (First Computer Programmer) Babbage owes a great debt to Lady Augusta Ada, Countess of Lovelace. Daughter of the famous romantic poet, Lord Byron, she was a brilliant mathematician who helped Babbage in his work. Above all, she documented his work, which Babbage never could bother to do. As a result we know about Babbage at all. Lady Augusta Ada also wrote programs to be run on Babbage’s machines. For this, she is recognized as the first computer programmer. Electro-Mechanical Computer: Census Tabulating Machine

Herman Hollerith Develop The tabulating machine. The tabulating machine was an electrical device designed to assist in summarizing information and, later, accounting. Invented by Herman Hollerith, the machine was developed to help process data for the 1890 U.S. Census. It spawned a larger class of devices known as unit record equipment and the data processing industry.

Harvard Mark I The IBM Automatic Sequence Controlled Calculator (ASCC), called the Mark I by Harvard University, was an electromechanical computer. The electromechanical ASCC was devised by Howard H. Aiken, built at IBM and shipped to Harvard in February 1944. It began computations for the U.S. Navy Bureau of Ships in May and was officially presented to the university on August 7, 1944.

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The ASCC was built from switches, relays, rotating shafts, and clutches. It used 765,000 components and hundreds of miles of wire, comprising a volume of 51 feet (16 m) in length, eight feet (2.4 m) in height, and two feet (~61 cm) deep. It had a weight of about 10,000 pounds (4500 kg). The basic calculating units had to be synchronized mechanically, so they were run by a 50-foot (~15.5 m) shaft driven by a five-horsepower (4 kW) electric motor. From the IBM Archives: The Automatic Sequence Controlled Calculator (Harvard Mark I) was the first operating machine that could execute long computations automatically. A project conceived by Harvard University's Dr. Howard Aiken, the Mark I was built by IBM engineers in Endicott, N.Y.

The first computer bug The lady is U.S. Rear Admiral Dr. Grace Murray Hopper, who worked with Howard Aiken from 1944 and used his machine for gunnery and ballistics calculation for the US Bureau of Ordnance's Computation project. One day, the program she was running gave incorrect results and, upon examination, a moth was found blocking one of the relays. The bug was removed and the program performed to perfection. Since then, a program error in a computer has been called a bug.

Electronic digital computers The Turing Machine

The "Turing" machine was described by Alan Turing in 1936, who called it an "automatic-machine". The Turing machine is not intended as a practical computing technology, but rather as a hypothetical device representing a computing machine. Turing machines help computer scientists understand the limits of mechanical computation. A Turing machine is a device that manipulates symbols on a strip of tape according to a table of rules. Despite its simplicity, a Turing machine can be adapted to simulate the logic of any computer algorithm, and is particularly useful in explaining the functions of a CPU inside a computer.

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Atanasoff-Berry Computer The ABC was built by Dr. Atanasoff and graduate student Clifford Berry in the basement of the physics building at Iowa State College during 1939-42.

The Atanasoff-Berry Computer (ABC) was the first electronic digital computing device. Conceived in 1937, the machine was not programmable, being designed only to solve systems of linear equations. It was successfully tested in 1942. However, its intermediate result storage mechanism, a paper card writer/reader, was unreliable, and when inventor John Vincent Atanasoff left Iowa State College for World War II assignments, work on the machine was discontinued. The ABC pioneered important elements of modern computing, including binary arithmetic and electronic switching elements, but its special-purpose nature and lack of a changeable, stored program distinguish it from modern computers.

Colossus computer Colossus was the world's first electronic, digital, programmable computer. Colossus and its successors were used by British codebreakers to help read encrypted German messages during World War II. They used thermionic valves (vacuum tubes) to perform the calculations.

Colossus was designed by engineer Tommy Flowers with input from Sidney Broadhurst, William Chandler, Allen Coombs and Harry Fensom. at the Post Office Research Station, Dollis Hill to solve a problem posed by mathematician Max Newman at Bletchley Park. The prototype, Colossus Mark 1, was shown to be working in December 1943 and was operational at Bletchley Park by February 1944. An improved Colossus Mark 2 first worked on 1 June 1944, just in time for the Normandy Landings. Ten Colossus computers were in use by the end of the war. The Colossus computers were used to help decipher teleprinter messages which had been encrypted using the Lorenz SZ40/42 machine—British codebreakers referred to encrypted German teleprinter traffic as "Fish" and called the SZ40/42 machine and its traffic "Tunny". Colossus compared two data streams, counting each match based on a programmable Boolean function. The encrypted message was read at high speed from a paper tape. The other stream was generated internally, and was an electronic simulation of the Lorenz machine at various trial settings. If the match count for a setting was above a certain threshold, it would be sent as output to an electric typewriter. 10

ENIAC ENIAC (Electronic Numerical Integrator And Computer) was conceived and designed by John Mauchly and J. Presper Eckert of the University of Pennsylvania. The team of design engineers assisting the development included Robert F. Shaw (function tables), Jeffrey Chuan Chu (divider/square-rooter), Thomas Kite Sharpless (master programmer), Arthur Burks (multiplier), Harry Huskey (reader/printer) and Jack Davis (accumulators).

ENIAC was the first general-purpose electronic computer. It was a Turing-complete digital computer capable of being reprogrammed to solve a full range of computing problems. ENIAC was designed to calculate artillery firing tables for the United States Army's Ballistic Research Laboratory. When ENIAC was announced in 1946 it was heralded in the press as a "Giant Brain". It boasted speeds one thousand times faster than electro- mechanical machines, a leap in computing power that no single machine has since matched. This mathematical power, coupled with general-purpose programmability, excited scientists and industrialists. The inventors promoted the spread of these new ideas by conducting a series of lectures on computer architecture.

Generations of Computers 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 process. 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. Each generation of computers is characterized by major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices. Read about each generation and the developments that led to the current devices that we use today.

First Generation - 1940-1956: Vacuum Tubes The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions. First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts. The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951. Second Generation (1956-1963) Transistors Transistors replaced vacuum tubes and ushered in the second generation of computers. The transistor was invented in 1947 but did not see widespread use in computers until the late 1950s. 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. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output. Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed

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programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.

Third Generation (1964-1971) Integrated Circuits The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers. Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors. Fourth Generation (1971-Present) Microprocessors The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the components of the computer—from the central processing unit and memory to input/output controls—on a single chip. In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors. As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices. Fifth Generation (Present and Beyond) Artificial Intelligence 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. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.

Space measurement units Computer speed and Measurement Unit The size of device in computers does not reflect the space available to store data in it. There are larger devices that can store only a few data where as many tiny devices that stores unbelievable amount of data. Because how long, how thick etc cannot determine how much we can store inside, we need to find some other way to measure space. Almost all of the computers use binary numbering systems (though there are some exceptions). Binary numbering system consists of only two digits - 0 and 1 to represent any quantity. 10 in binary is equal to the 2 and 100 to 5. We will be learning this numbering system after some days. Everything in computers is represented in strings of binary numbers. For example capital A is interpreted by computer as 0100 0001 and B is 0100 0010. All characters, numbers, symbols, images, sounds, animations, videos and everything, yes everything is converted into suitable binary code to store in computer or process by computer. So if there is any device that can store one binary digit (whether 0 or 1), its storage capacity is 1 bit. We've already learned that bit is the abbreviation of binary digit. Any device that has storage space to accommodate 5 binary digits has 5 bits space. You require thousands and millions of bits for a file and expressing the space available in bits only is really inconvenient because it will be an extremely large number. So, we have larger units that represent a group of lower units. A group of 4 binary digits is called a nibble (4 bits = 1 Nibble). Similarly a group of 8 bits is called a byte (1 byte = 8 bits). As you have seen the example above, each character requires 8 bits which is 1 byte. So 1 character requires 1 byte space. Now, if you have a text file whose size is 32 bytes, it means there are 32 x 8 binary digits (0s and 1s) stored in it. In the metric system 1000 lifts up the unit to the higher such as 1000 meter is 1 kilometer, 1000 liter is 1 kiloliter etc. In binary numbering system it is 1024 (=2^ 10) that converts to higher unit. Following table lists the different units and their values: 12

Space Measurement Units Units 0 or 1 = 1 Bit 4 bits = 1 Nible 8 bits = 1 Byte 1024 bytes 1 Kilobytes 1024KB=1 Megabytes 1024 Megabytes = 1 Giga Byte 1024 GB=1 Terabytes 1024 TB=1 Petabytes 1024 Petabytes=1 ExaByte

Speed Measurement Units Speed is related to time. Computer can perform millions of tasks in one second. So to compare the speed of computer operation (execution of programs and instructions) we require some units that can represent a very small fraction of time. The unit of measurement used to measure a computer's clock speed is called a hertz (Hz). This denotes one cycle per second and measures a clock's speed. In computer clock speed, one hertz is equivalent to one tick per second. A computer's clock speed is normally measured in MHz (megahertz) or GHz (gigahertz). 1 Hertz 1000Hz=1 Kilohertz 1000 Kilohertz= 1 Megahertz 1000 Megahertz=1 Gigahertz 1000 Gigahertz=1 Terahertz

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CLASSIFICATION OF COMPUTER

On the basis of size

The digital computers that are available nowadays vary in their sizes and types. The computers are broadly classified into four categories (Figure) based on their size and type—(1) Microcomputers, (2) Minicomputers, (3) Mainframe computers, and (4) Supercomputer. Microcomputers

Classification of computers based on size and typeMicrocomputers are small, lowcost and single-user digital computer. They consist of CPU, input unit, output unit, storage unit and the software. Although microcomputers are stand-alone machines, they can be connected together to create a network of computers that can serve more than one user. IBM PC based on Pentium microprocessor and Apple Macintosh are some examples of microcomputers. Microcomputers include desktop computers, notebook computers or laptop, tablet computer, handheld computer, smart phones and notebook. Desktop Computer or Personal Computer (PC) is the most common type of microcomputer. It is a stand-alone machine that can be placed on the desk. Externally, it consists of three units—key-board, monitor, and a system unit containing the CPU, memory, hard disk drive, etc. It is not very expensive and is suited to the needs of a single user at home, small business units, and organizations. Apple, Microsoft, HP, Dell and Lenovo are some of the PC manufacturers. Notebook Computers or Laptop resemble a notebook. They are portable and have all the features of a desktop computer. The advantage of the laptop is that it is small in size (can be put inside a briefcase), can be carried anywhere, has a battery backup and has all the functionality of the desk-top. Laptops can be placed on the lap while working (hence the name). Laptops are costlier than the desktop machines. Netbook These are smaller notebooks optimized for low weight and low cost, and are designed for accessing web-based applications. Starting with the earliest netbook in late 2007, they have gained significant popularity now. Netbooks deliver the performance needed to enjoy popular activities like streaming videos or music, emailing, Web surfi ng or instant messaging. The word netbook was created as a blend of Internet and notebook. Tablet Computer has features of the notebook computer but it can accept input from a stylus or a pen instead of the keyboard or mouse. It is a portable computer. Tablet computer are the new kind of PCs. Handheld Computer or Personal Digital Assistant (PDA) is a small computer that can be held on the top of the palm. It is small in size. Instead of the keyboard, PDA uses a pen or a14stylus for input. PDAs do not have a disk drive. They have a limited memory and are less powerful. PDAs can be connected to the Internet via a wireless connection. Casio and Apple are some of the manufacturers of PDA. Over the last few years, PDAs have merged into mobile phones to create smart phones.

Smart Phones are cellular phones that function both as a phone and as a small PC. They may use a stylus or a pen, or may

have a small keyboard. They can be connected to the Internet wirelessly. They are used to access the electronic-mail, download music, play games, etc. Blackberry, Apple, HTC, Nokia and LG are some of the manufacturers of smart phones. Minicomputers

Minicomputers are digital computers, generally used in multi-user systems. They have high processing speed and high storage capacity than the microcomputers. Minicomputers can support 4-200 users simultaneously. The users can access the minicomputer through their PCs or terminal. They are used for real-time applications in industries, research centers, etc. PDP 11, IBM (8000 series) are some of the widely used minicomputers. Mainframe Computers

Mainframe computers are multi-user, multi-programming and high performance computers. They operate at a very high speed, have very large storage capacity and can handle the workload of many users. Mainframe computers are large and powerful systems generally used in centralized databases. The user accesses the mainframe computer via a terminal that may be a dumb terminal, an intelligent terminal or a PC. A dumb terminal cannot store data or do processing of its own. It has the input and output device only. An intelligent terminal has the input and output device, can do processing, but, cannot store data of its own. The dumb and the intelligent terminal use the processing power and the storage facility of the mainframe computer. Mainframe computers are used in organizations like banks or companies, where many people require frequent access to the same data. Some examples of mainframes are CDC 6600 and IBM ES000 series. Supercomputers

Supercomputers are the fastest and the most expensive machines. They have high processing speed compared to other computers. The speed of a supercomputer is generally measured in FLOPS (Floating point Operations Per Second). Some of the faster supercomputers can perform trillions of calculations per second. Supercomputers are built by interconnecting thousands of processors that can work in parallel. Supercomputers are used for highly calculation intensive tasks, such as, weather forecasting, climate research (global warming), molecular research, biological research, nuclear research and

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aircraft design. They are also used in major universities, military agencies and scientific research laboratories. Some examples of supercomputers are IBM Roadrunner, IBM Blue gene and Intel ASCI red. PARAM is a series of supercomputer assembled in India by C-DAC (Center for Development of Advanced Computing), in Pune. PARAM Padma is the latest machine in this series. The peak computing power of PARAM Padma is 1 Tera FLOP (TFLOP).

On the basis of working principle Digital computers:

Digital computers operates on inputs which are on-off type (being digit 1 and 0) and its outputs is also in form of on-off signals. Digital computers are based on counting operation. Any data to be manipulated by a digital computer must first be converted to a discrete(1, 0) representation. Digital describes electronic technology that generates, stores, and processes data in terms of two states: positive and non-positive. Positive is expressed or represented by the number 1 and nonpositive by the number 0. Thus, data transmitted or stored with digital technology is expressed as a string of 0's and 1's. Each of these state digits is referred to as a bit (and a string of bits that a computer can address individually as a group is a byte). There is a practical limit to the accuracy of the readings of analog devices, usually to the nearest tenth of the unit of measure. Thus if water in a beaker was being heated and its temperature rose from 50 C to 51 C ,someone observing the thermometer might only be able to distinguish the temperature 50.0, 50.1, 50.2... 50.9, 51.0. However, on a digital computer, we could simulate to rise in temperature whatever degree of accuracy we want; so that if we wish, we could let the increment be 0.1, 0.01, 0.001,etc.there digital computers are more accurate than analog computers. Analog computers:

The analog computer operate by measuring rather than counting. It measure continually, usually of a physical nature data such as lengths, voltages, or currents. It does not produce number but produces its results in the form of graph. It is more efficient in continues calculations. Analog machines are usually special purpose devices, dedicated to a single task.

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Hybrid computers:

A hybrid computer is combination of both analog and digital computer i.e. a part of processing is done on analog computer and a part on digital computer. A hybrid computer combines the best characteristics of both analog and digital computer. It can accept input data in both analog and digital form. It is used for simulation application.

On the basis of brand On the basis of brand , the computer can be classified as IBM PC, IBM compatibles and Apple/Macintosh computer. IBM PC:

IBM PC is the largest computer manufacturing company establishing USA. The computer manufactures by IBM PC or branded computer. Personal Computer (PC) is the most important type of microcomputer system. The microcomputer manufacture by IBM company are called IBM PC. These computers are reliable, durable and have better quality but they are costly.

IBM compatibles: The computers that have some functional characteristics and principles of IBM computer are called IBM compatibles. In other word, all the computer are manufactured by the another companies rather than IBM company are Known as IBM compatibles. All the software and hardware of IBM compatibles. These are cheaper and Their Parts are easily available in Market. they are also duplicate or assemble computer. Apple/Macintosh Computer:

All the computers manufacture by apple cooperation, a leading computers manufacturing computer of USA are known as apple/Macintosh computers. These computer use their own software and hardware. They are totally different than that of IBM computers, In terms of both hardware and software. For e.g. software developed for apple computer can't run or IBM computers and vice -versa. Similarly, floppy disk formatting in IBM computer can't be recognized by apple Macintosh computer and vice -versa. It is popularly used in desktop publishing (DTP) houses a s they provide better quality of graphic output.

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On the Basis of Model On the basis of model computer is classified as: XT (Extended / Extra Technology) Computer The computers that use 8086, 8088 microprocessor are called XT computers. The time periods for this computer are from 1975 - 1982. XT computers have processing speed of 4.77 MHz and are comparatively slow in speed. These processors are of 4, 8 or 16 bits of word length. AT (Advanced Technology) Computer With the development of 80286 microprocessor AT computer were introduced in the field of computers. The processors are of 8, 16, 32 or 64 bits of word length. The computers using Pentium I, Pentium pro & Pentium II are the examples of AT computers. The time periods for these computers are from 1982 - 1995. These computers can run any type of soft wares including text based as well as graphical base and processor speed of these computers is up to 233 MHz. PS/2 (Personal System / 2) Computer IBM started manufacturing next model of computer since 1990. This model is called PS? 2 computers. Most of the computers manufactured after 1990 including laptop, belongs to this model. These computers are refinement of AT computers. These computers can run almost all software & programs.

Mobile Computing Mobile computing' is a form of human -computer interaction by which a computer is expected to be transported during normal usage. Mobile computing has three aspects: mobile communication, mob ile hardware, and mobile software. The first aspect addresses communication issues in ad -hoc and infrastructure networks as well as communication properties, protocols, data formats and concrete technologies. The second aspect is on the hardware, e.g., mob ile devices or device components. The third aspect deals with the characteristics and requirements of mobile applications.

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UNIT II, Input Devices In computing, an input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or other information appliance. Many input devices can be classified according to: • • •

Modality of input (e.g. mechanical motion, audio, visual, etc.) the input is discrete (e.g. key presses) or continuous (e.g. a mouse's position, though digitized into a discrete quantity, is fast enough to be considered continuous) the number of degrees of freedom involved (e.g. two-dimensional traditional mice, or three-dimensional navigators designed for CAD applications)

Keyboards It is a text base input device that allows the user to input alphabets, numbers and other characters. It consists of a set of keys mounted on a board. Alphanumeric Keypad It consists of keys for English alphabets, 0 to 9 numbers, and special characters like + - / * ( ) etc. Function Keys There are twelve function keys labeled F1, F2, F3... F12. The functions assigned to these keys differ from one software package to another. These keys are also user programmable keys. Special-function Keys These keys have special functions assigned to them and can be used only for those specific purposes. Functions of some of the important keys are defined below.

Enter It is similar to the 'return' key of the typewriter and is used to execute a command or program. Spacebar It is used to enter a space at the current cursor location. Backspace This key is used to move the cursor one position to the left and also delete the character in that position. Delete It is used to delete the character at the cursor position. Insert Insert key is used to toggle between insert and overwrite mode during data entry. Shift This key is used to type capital letters when pressed along with an alphabet key. Also used to type the special characters located on the upper-side of a key that has two characters defined on the same key. Caps Lock Cap Lock is used to toggle between the capital lock features. When 'on', it locks the alphanumeric keypad for capital letters input only. Tab Tab is used to move the cursor to the next tab position defined in the document. Also, it is used to insert indentation into a document. Ctrl Control key is used in conjunction with other keys to provide additional functionality on the keyboard. Alt Also like the control key, Alt key is always used in combination with other keys to perform specific tasks. Esc This key is usually used to negate a command. Also used to cancel or abort executing programs. Numeric Keypad Numeric keypad is located on the right side of the keyboard and consists of keys having numbers (0 to 9) and mathematical operators (+ - * /) defined on them. This keypad is provided to support quick entry for numeric data. Cursor Movement Keys These are arrow keys and are used to move the cursor in the direction indicated by the arrow (up, down, left, right).

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Mouse

The mouse is a small device used to point to a particular place on the screen and select in order to perform one or more actions. It can be used to select menu commands, size windows, start programs etc. The most conventional kind of mouse has two buttons on top: the left one being used most frequently. Mouse Actions Left Click : Used to select an item. Double Click : Used to start a program or open a file. Right Click : Usually used to display a set of commands. Drag and Drop : It allows you to select and move an item from one location to another. To achieve this place the cursor over an item on the screen, click the left mouse button and while holding the button down move the cursor to where you want to place the item, and then release it.

Joystick The joystick is a vertical stick which moves the graphic cursor in a direction the stick is moved. It typically has a button on top that is used to select the option pointed by the cursor. Joystick is used as an input device primarily used with video games, training simulators and controlling robots.

Scanner Scanner is an input device used for direct data entry from the source document into the computer system. It converts the document image into digital form so that it can be fed into the computer. Capturing information like this reduces the possibility of errors typically experienced during large data entry. Hand-held scanners are commonly seen in big stores to scan codes and price information for each of the items. They are also termed the bar code readers. Light Pen

It is a pen shaped device used to select objects on a display screen. It is quite like the mouse (in its functionality) but uses a light pen to move the pointer and select any object on the screen by pointing to the object. Users of Computer Aided Design (CAD) applications commonly use the light pens to directly draw on screen. 20

Touch Screen It allows the user to operate/make selections by simply touching the display screen. Common examples of touch screen include bank ATM, touch pad etc. Digital camera A digital camera can store many more pictures than an ordinary camera. Pictures taken using a digital camera are stored inside its memory and can be transferred to a computer by connecting the camera to it. A digital camera takes pictures by converting the light passing through the lens at the front into a digital image. The Speech Input Device The "Microphones - Speech Recognition" is a speech Input device. To operate it we require using a microphone to talk to the computer. Also we need to add a sound card to the computer. The Sound card digitizes audio input into 0/1s .A speech recognition program can process the input and convert it into machine-recognized commands or input. OMR(Optical Mark Recognition)

Many traditional OMR (Optical Mark Recognition) devices work with a dedicated scanner device that shines a beam of light onto the form paper. The contrasting reflectivity at predetermined positions on a page is then utilized to detect the marked areas because they reflect less light than the blank areas of the paper. This device is designed to be able to read markings that have been placed in specific places on a form or card. The person filling out the form/card will either color in a series of small squares or perhaps make a cross within the square. The device then scans the card and senses where marks have been placed.

In contrast to the dedicated OMR device, desktop OMR software allows a user to create their own forms in a word processor and print them on a laser printer. The OMR software then works with a common desktop image scanner with a document feeder to process the forms once filled out. OCR(Optical character recognition)

Optical character recognition, usually abbreviated to OCR, is the mechanical or electronic translation of scanned images of handwritten, typewritten or printed text into machine-encoded text. It is widely used to convert books and documents into electronic files, to computerize a record-keeping system in an office, or to publish the text on a website. OCR makes it possible to edit the text, search for a word or phrase, store it more compactly, display or print a copy free of scanning artifacts, and apply techniques such as machine translation, text-to-speech and text mining to it. OCR is a field of research in pattern recognition, artificial intelligence and computer vision. OCR systems require calibration to read a specific font; early versions needed to be programmed with images of each

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character, and worked on one font at a time. "Intelligent" systems with a high degree of recognition accuracy for most fonts are now common. Some systems are capable of reproducing formatted output that closely approximates the original scanned page including images, columns and other non-textual components.

BCR(bar code reader)

A barcode reader (or barcode scanner) is an electronic device for reading printed barcodes. Like a flatbed scanner, it consists of a light source, a lens and a light sensor translating optical impulses into electrical ones. Additionally, nearly all barcode readers contain decoder circuitry analyzing the barcode's image data provided by the sensor and sending the barcode's content to the scanner's output port.

MICR

MICR (magnetic ink character recognition) is a technology used to verify the legitimacy or originality of paper documents, especially checks. Special ink, which is sensitive to magnetic fields, is used in the printing of certain characters on the original documents. Information can be encoded in the magnetic characters. The use of MICR can enhance security and minimize the losses caused by some types of crime. If a document has been forged for example, a counterfeit check produced using a color photocopying machine, the magnetic-ink line will either not respond to magnetic fields, or will produce an incorrect code when scanned using a device designed to recover the information in the magnetic characters. Even a legitimate check can be rejected if the MICR reader indicates that the owner of the account has a history of writing bad checks. Retailers commonly use MICR readers to minimize their exposure to check fraud. Corporations and government agencies also use the technology to speed up the sorting of documents. 22

UNIT III Output devices An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) to the outside world. In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world. Inputs are the signals or data sent to the system, and outputs are the signals or data sent by the system to the outside.

Monitor A monitor or display (also called screen or visual display unit) is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) thin panel, while older monitors use a cathode ray tube about as deep as the screen size. Different image techniques have been used for Computer monitors. Until the 21st century most monitors were CRT but they have been phased out for LCD monitors. Types of monitors: 1, CRT 2,Flat Panel Monitors 3, LCD (liquid crystal display) 4, LED (light-emitting diodes) 5, plasma display panel (PDP)

1, CRT (cathode ray tube) monitors

This monitor uses a Cathode Ray Tube (CRT). CRT tube creates an image on the screen using a beam of electrons. CRT consists of one or more guns that fire a beam of electrons inside the screen. The screen is coated with very tiny Phosphor dots from inside. The beam of electrons repeatedly falls on the surface of screen. Every beam fall takes only a fraction of second. CRT in color monitors consists of three guns. These guns generate red, green and blue (RGB) colors. The other colors are generated with a combination of these three colors. Nowadays, most of the CRT monitors are replaced by Flat Panel Monitors. 2, Flat Panel Monitors

Flat Panel Monitors take less space and are lightweight. These monitors use much less power than CRTs. It does not produce harmful radiations. It is much expensive than CRT. Notebook computers, PDA and cellular phones use flat panel monitors. Flat panel monitors are available in different sizes such as 15”, 17”, 18” & 19” etc. Flat panel display is made up of two plates of glass. These plates contain a substance between them. The substance is activated in different ways. There are 3 types of technologies used in flat panel display screens:

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• Liquid Crystal Display • LED (light-emitting diodes) • Gas plasma Display 2.1, Liquid Crystal Display

Liquid crystal display screen contains a substance called liquid crystal. The molecules of this substance lineup in such a way that the light behind the screens blocked or allowed to create an image. LCDs provide a sharper picture than CRTs and emit less radiation. LCD displays requires less power and take up less space than CRT. 2.2, LED (light-emitting diodes)

LED monitors are the latest types of monitors on the market today. These are flat panel, or slightly curved displays which make use of light-emitting diodes for back-lighting, instead of cold cathode fluorescent (CCFL) back-lighting used in LCDs. LED monitors are said to use much lesser power than CRT and LCD and are considered far more environmentally friendly. The advantages of LED monitors are that they produce images with higher contrast, have less negative environmental impact when disposed, are more durable than CRT or LCD monitors, and features a very thin design. They also don’t produce much heat while running. The only downside is that they can be more expensive, especially for the high-end monitors like the new curved displays that are being released. 24

2.3, Gas plasma Display

Gas plasma display uses gas plasma technology. This technology uses a layer of gas between two glass plates. The gas release ultraviolet light when voltage is applied. The pixels on the screen glow due to this ultraviolet light and form an image. Plasma display is available in the sizes of upto 150 inches wide. It provides richer colors than LCD monitors but are more expensive. That is why, it is not commonly used. It provides higher display quality. This type of monitor can hand directly on a wall. 3, Touch Screen Monitors Touch screen monitors are used for input as well as output. A touch screen is a special type of visual display unit. It has a grid of light beams or fine wires on the screen. It lets the user to interact with a computer by the touch of a finger rather than typing on a keyboard or moving a mouse. The user enters data by touching icons or menus identified on the screen. Most touch screen computers use sensors to detect touch of a finger. Touch screen is well suited for simple applications like ATM. It has also become common in department stores and supermarkets. Types of touch Screen Monitors There are different types of touch screen technology: • Resistive Touch Screen • Surface acoustic wave (SAW) touch panels • Surface capacitive touch panels • Projected capacitive touch panels • Optical touch panels (infrared optical imaging touch panels) 3.1 Resistive Touch Screen

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This monitor usually has a coat of thin electrically conductive and resistive layer of metal. A change in electrical current occurs when it is pressed. The input can be processed by a computer. These monitors are the most popular types of touch screen monitors used today. They are usually not affected by dust or liquids which make them very reliable. 3.2 Surface acoustic wave (SAW) touch panels

These monitors use ultrasonic waves to process input from the screen. These waves flow over the touch screen. The wave is absorbed and processed by computer when a person touches the pad. 3.3 Surface capacitive touch panels

These screens are coated with indium tin oxide. This material provides continuous current across the screen. The current can be measure by the processor when the pad is touched. It is usually used with a bare finger 26

instead of stylus. These screens have high clarity and are not affected by dust. Nowadays most of the smartphones have Capacitive Touch screens. 3.4 Projected capacitive touch panels

Projected capacitive touch panels are often used for smaller screen sizes than surface capacitive touch panels. They've attracted significant attention in mobile devices. The iPhone, iPod Touch, and iPad use this method to achieve high-precision multi-touch functionality and high response speed. A unique characteristic of a projected capacitive touch panel is the fact that the large number of electrodes enables accurate detection of contact at multiple points (multi-touch). The internal structure of these touch panels consists of a substrate incorporating an IC chip for processing computations, over which is a layer of numerous transparent electrodes is positioned in specific patterns. The surface is covered with an insulating glass or plastic cover. When a finger approaches the surface, electrostatic capacity among multiple electrodes changes simultaneously, and the position were contact occurs can be identified precisely by measuring the ratios between these electrical currents. 3.5 Optical touch panels (infrared optical imaging touch panels)

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The category of optical touch panels includes multiple sensing methods. The number of products employing infrared optical imaging touch panels based on infrared image sensors to sense position through triangulation has grown in recent years, chiefly among larger panels. A touch panel in this category features one infrared LED each at the left and right ends of the top of the panel, along with an image sensor (camera). Retroreflective tape that reflects incident light along the axis of incidence is affixed along the remaining left, right, and bottom sides. When a finger or other object touches the screen, the image sensor captures the shadows formed when the infrared light is blocked. The coordinates of the location of contact are derived by triangulation. Printer

Printers are used to produce paper (commonly known as hardcopy) output. When we talk about printers we refer to two basic qualities associated with printers resolution and speed. Print resolution is measured in terms of number of dots per inch (dpi). Print speed is measured in terms of number of characters printed in a unit of time and is represented as characters-per-second (cps), lines-per- minute (lpm), or pages-per-minute (ppm). Based on the technology used, they can be classified as Impact or Non-impact printers. Impact printers

Impact printers use the typewriting printing mechanism wherein a hammer strikes the paper through a ribbon in order to produce output. Dot-matrix and Character printers fall under this category. Non-impact printers

Non-impact printers do not touch the paper while printing. They use chemical, heat or electrical signals to etch the symbols on paper. Inkjet, Deskjet, Laser, Thermal printers fall under this category of printers. Plotter

Plotters are used to print graphical output on paper. It interprets computer commands and makes line drawings on paper using multicolored automated pens. It is capable of producing graphs, drawings, charts, maps etc. Computer Aided Engineering (CAE) applications like CAD (Computer Aided Design) and CAM (Computer Aided Manufacturing) are typical usage areas for plotters. Audio Output: Sound Cards and Speakers:

The Audio output is the ability of the computer to output sound. Two components are needed: Sound card - Plays contents of digitized recordings, Speakers - Attached to sound card.

Computer Peripherals A peripheral is a device attached to a host computer, but not part of it, and is more or less dependent on the host. It expands the host's capabilities, but does not form part of the core computer architecture. Examples are computer printers, image scanners, tape drives, 28 microphones, loudspeakers, webcams, and digital cameras etc.

UNIT IV Storage Devices or Computer Memory

In computing, memory refers to the physical devices used to store programs (sequences of instructions) or data (e.g. program state information) on a temporary or permanent basis for use in a computer or other digital electronic device. The term primary memory is used for the information in physical systems which are fast (i.e. RAM), as a distinction from secondary memory, which are physical devices for program and data storage which are slow to access but offer higher memory capacity. Primary memory stored on secondary memory is called "virtual memory". Processor register (CPU Register)

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In computer architecture, a processor register is a small amount of storage available as part of a digital processor, such as a central processing unit (CPU). Such registers are typically addressed by mechanisms other than main memory and can be accessed faster. Almost all computers, load-store architecture or not, load data from a larger memory into registers where it is used for arithmetic, manipulated or tested by machine instructions. Manipulated data is then often stored back into main memory, either by the same instruction or a subsequent one. Modern processors use either static or dynamic RAM as main memory, with the latter usually accessed via one or more cache levels. Cache-Memory

In computer engineering, a cache is a component that transparently stores data so that future re quests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere. If requested data is contained in the cache (cache hit), this requ est can be served by simply reading the cache, which is comparatively faster. Otherwise (cache miss), the data has to be recomputed or fetched from its original storage location, which is comparatively slower. Hence, the greater the number of requests that can be served from the cache, the faster the overall system performance becomes. To be cost efficient and to enable an efficient use of data, caches are relatively small. Nevertheless, caches have proven themselves in many areas of computing because access patterns in typical computer applications have locality of reference. References exhibit temporal locality if data is requested again that has been recently requested already. References exhibit spatial locality if data is requested that is physically stored close to data that has been requested already.

Cache (L1) The Level 1 cache, or primary cache, is on the CPU and is used for temporary storage of instructions and data organized in blocks of 32 bytes. Primary cache is the fastest form of storage. Because it's built in to the chip with a zero wait-state (delay) interface to the processor's execution unit, it is limited in size. For all L1 cache designs the control logic of the primary cache keeps the most frequently used data and code in the cache and updates external memory only when the CPU hands over control to other bus masters, or during direct memory access by peripherals. Cache (L2) Most PCs are offered with a Level 2 cache to bridge the processor/memory performance gap. Level 2 cache - also referred to as secondary cache) uses the same control logic as Level 1 cache. The aim of the Level 2 cache is to supply stored information to the processor without any delay (wait-state). For this purpose, the bus interface of the processor has a special transfer protocol called burst mode. A burst cycle consists of four data transfers where only the address of the first 64 is output on the address bus. The most common Level 2 cache is synchronous pipeline burst.

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Primary memory Primary memory (or main memory or internal memory), often referred to simply as memory, is the only one directly accessible to the CPU. The CPU continuously reads instructions stored there and executes them as required. Any data actively operated on is also stored there in uniform manner. It can be divided into two essential types: RAM and ROM. RAM(Volatile memory) RAM (random access memory) is the place in a computer where the operating system, application programs, and data in current use are kept so that they can be quickly reached by the computer's processor. RAM is much faster to read from and write to than the other kinds of storage in a computer, the hard disk, floppy disk, and CD- ROM. However, the data in RAM stays there only as long as your computer is running. When you turn the computer off, RAM loses its data. When you turn your computer on again, your operating system and other files are once again loaded into RAM, usually from your hard disk. There are two different types of RAM: DRAM (Dynamic Random Access Memory) SRAM (Static Random Access Memory) DRAM (Dynamic Random Access Memory) Dynamic RAM is a type of RAM that only holds its data if it is continuously accessed by special logic called a refresh circuit. Many hundreds of times each second, this circuitry reads the contents of each memory cell, whether the memory cell is being used at that time by the computer or not. Due to the way in which the cells are constructed, the reading action itself refreshes the contents of the memory. If this is not done regularly, then the DRAM will lose its contents, even if it continues to have power supplied to it. This refreshing action is why the memory is called dynamic. SRAM (Static Random Access Memory Static RAM is a type of RAM that holds its data without external refresh, for as long as power is supplied to the circuit. This is contrasted to dynamic RAM (DRAM), which must be refreshed many times per second in order to hold its data contents. SRAMs are used for specific applications within the PC, where their strengths outweigh their weaknesses compared to DRAM: • Simplicity: SRAMs don't require external refresh circuitry or other work in order for them to keep their data intact. • Speed: SRAM is faster than DRAM. In contrast, SRAMs have the following weaknesses, compared to DRAMs: • Cost: SRAM is, byte for byte, several times more expensive than DRAM. • Size: SRAMs take up much more space than DRAMs (which is part of why the cost is higher). Read-Only Memory (ROM) One major type of memory that is used in PCs is called read-only memory, or ROM for short. ROM is a type of memory that normally can only be read, as opposed to RAM which can be both read and written. There are two main reasons that read-only memory is used for certain functions within the PC: Permanence: The values stored in ROM are always there, whether the power is on or not. A ROM can be removed from the PC, stored for an indefinite period of time, and then replaced, and the data it contains will still be there. For this reason, it is called non-volatile storage. Security: The fact that ROM cannot easily be modified provides a measure of security against accidental (or malicious) changes to its contents. Read-only memory is most commonly used to store system-level programs that we want to have available to the PC at all times. The most common example is the system BIOS program, which is stored in a ROM called (amazingly enough) the system BIOS ROM. Having this in a permanent ROM means it is available when the power is turned on so that the PC can use it to boot up the system. Remember that when you first turn on the PC the system memory is empty, so there has to be something for the PC to use when it starts up. There are several ROM variants that can be changed under certain circumstances; the following are the different types of ROMs with a description of their relative modifiability:

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• ROM:

A regular ROM is constructed from hard -wired logic, encoded in the silicon itself, much the way that a processor is. It is designed to perform a specific function and cannot be changed. This is inf lexible and so regular ROMs are only used generally for programs that are static (not changing often) and mass -produced. This product is analogous to a commercial software CD -ROM that you purchase in a store. • Programmable ROM (PROM):

This is a type of ROM that can be programmed using special equipment; it can be written to, but only once. This is useful for companies that make their own ROMs from software they write,because when they change their code they can create new PROMs without requiring expensive e quipment. This is similar to the way a CD - ROM recorder works by letting you "burn" programs onto blanks once and then letting you read from them many times. In fact, programming a PROM is also called b urni ng , just like burning a CD-R, and it is comparable in terms of its flexibility. • Erasable Programmable ROM (EPROM):

An E PR OM is a ROM that can be erased and reprogrammed. A little glass window is installed in the top of the ROM package, through which you can actually see the chip that holds the memory. Ult raviolet light of a specific frequency can be shined through this window for a specified period of time, which will erase the EPROM and allow it to be reprogrammed again. Obviously this is much more useful than a regular PROM, but it does require the erasi ng light. Continuing the "CD" analogy, this technology is analogous to a reusable CD -RW. 32

• Electrically Erasable Programmable ROM (EEPROM): The next level of eras ability is the E E PR OM , which can be

erased under software control. This is the most flexible type of ROM, and is now commonly used for holding BIOS programs. Electrically Erasable Programmable Read-Only Memory (EEPROM) is a stable, non-volatile memory storage system that is used for storing minimal data quantities in computer and electronic systems and devices, such as circuit boards. This data may be stored, even without a permanent power source, as device configuration or calibration tables. If storing higher volumes of data that is static (like in USB drives), certain types of EEPROM (like flash memory) are more cost-effective than conventional EEPROM devices.

Secondary memory Secondary memory (also known as external memory or auxiliary storage or Secondary Storage), differs from primary storage in that it is not directly accessible by the CPU. The computer usually uses its input/output channels to access secondary storage and transfers the desired data using intermediate area in primary storage. Secondary storage does not lose the data when the device is powered down—it is non-volatile. Per unit, it is typically also two orders of magnitude less expensive than primary storage. Consequently, modern computer systems typically have two orders of magnitude more secondary storage than primary storage and data are kept for a longer time there. Some examples of secondary storage technologies are: Hard Disk, Floppy Disk, magnetic tape etc.

Storage Device Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data. Data storage is a core function and fundamental component of computers. Storage Device Types: Magnetic Tape, Hard Disk, Floppy Disk, Flash Memory, Optical Disk(CD,VCD,DVD), External Storage Device Magnetic Tape:

Magnetic tapes are used for large computers like mainframe computers where large volume of data is stored for a longer time. In PC also can use tapes in the form of cassettes. The storage of data in tapes is inexpensive. Tapes consist of

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magnetic materials that store data permanently. It can be 12.5 mm to 25 mm wide plastic film-type and 500 meter to 1200 meter long, which is coated with magnetic material. The tape unit is connected to the central processor and information is fed into or read from the tape through the processor. It is similar to a cassette tape recorder. Magnetic Disk (HDD): Magnetic disks used in computer are made on the circular disk and coated with magnetic material.

It rotates with very high speed inside the computer drive. Data is stored on both the surfaces of the disk. Magnetic disks are most popular as direct access storage device. Each disk consists of a number of invisible concentric circles called tracks. Information is recorded on tracks of a disk surface in the form of tiny magnetic spots. The presence of a magnetic spot represents one bit and its absence represents zero bit. The information stored in a disk can be read many times without affecting the stored data. So the reading operation is non-destructive. But if you want to write a new data, then the existing data is erased from the disk and new data is recorded.

Floppy Disk: It is similar to magnetic disk. It is 3.5 inch in diameter. These come in single or double density and recorded on one or both surface of the diskette. The capacity of a high-density 3.5 inch floppy it is 1.44 megabytes. It is cheaper than any other storage devices and is portable. The floppy is a low cost device particularly suitable for personal computer system. Optical Disk: With every new application and software there is greater demand for memory capacity. It is the necessity to store large volume of data that has led to the development of optical disk storage medium. Optical disks read and write the data using light. Optical disks can be divided into the following categories: 1. Compact Disk/Read Only Memory (CD-ROM): CD-ROM disks are made of reflective metals. CD-ROM is written during the process of manufacturing by high power laser beam. Here the storage density is very high, storage cost is very low and access time is relatively fast. Each disk is approximately 4 A inches in diameter and can have over 600 MB of data. As the CD-ROM can be read only we cannot write or make changes into the data contained in it. 34

2. Write Once, Read Many (WORM): The inconvenience that we cannot write anything onto a CD-ROM is avoided in WORM. A WORM allows the user to write data permanently on to the disk. Once the data is written it can never be erased without physically damaging the disk. Here data can be recorded from keyboard, video scanner, OCR equipment and other devices. The advantage of WORM is that it can store vast amount of data amounting to gigabytes (10' bytes). Any document in a WORM can be accessed very fast, say less than 30 seconds. 3. Erasable Optical Disk: These are optical disks where data can be written, erased and re-written. This makes use of a laser beam to write and re-write the data. These disks may be used as alternatives to traditional disks. Erasable optical disks are based on a technology known as magneto-optico (MO). To write a data bit on to the erasable optical disk the MO drive's laser beam heats a tiny, precisely defined point on the disk's surface and magnetizes it. 4. A DVD ("digital versatile disc" or "digital video disc") is an optical disc storage media format, invented and developed by Philips, Sony,Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions. Pre-recorded DVDs are mass-produced using molding machines that physically stamp data onto the DVD. Such discs are known as DVD-ROM, because data can only be read and not written nor erased. Blank recordable DVDs (DVD- R and DVD+R) can be recorded once using optical disc recording technologies and supported by optical disc drives and DVD recorder sand then function as a DVD-ROM. Rewritable DVDs (DVD-RW, DVD+RW, and DVD-RAM) can be recorded and erased multiple times. 5. Flash memory Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM (electrically erasable programmable read-only memory) and must be erased in fairly large blocks before these can be rewritten with new data. Example applications of both types of flash memory include personal computers, PDAs, digital audio players, digital cameras, mobile phones, synthesizers, video games, scientific instrumentation, industrial robotics, medical electronics, and so on. In addition to being non-volatile, flash memory offers fast read access times, as fast as dynamic RAM, although not as fast as static RAM or ROM. Its mechanical shock resistance helps explain its popularity over hard disks in portable devices; as does its high durability etc. 6. External Storage Device or auxiliary Storage device In computing, external storage comprises devices that temporarily store information for transporting from computer to computer. Such devices are not permanently fixed inside a computer. Semiconductor memories are not sufficient to provide the whole storage capacity required in computers. The major limitation in using semiconductor memories is the cost per bit of the stored information. So to fulfill the large storage requirements of computers, magnetic disks, optical disks are generally used. Advantages of external storage: • External storage provides additional storage other than that available in a computer. • Data can be transported easily from one place to another. • It is useful to store software and data that is not needed frequently. • External storage also works as data backup. • This back up may prove useful at times such as fire or theft because important data is not lost.

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UNIT V Computer rchitecture Computer architecture is the design which deals with the operational activities of the computer. The computer architecture is also known as the digital computer organizational design which deals with the computer system and for that the fundamental operations needs to be identified. All the requirement which are needed for the computer architecture are to be listed down and at times the blueprint technique is also used by the computer architecture so that all things could be performed in a much better way. The implementations requirement must also be known so that they could be implemented on to the different parts of the computer. Represents the attributes associated with computer systems for Example: Set the instruction, the arithmetic is used, addressing technique, the mechanism of I / O. Computer architecture is related to Computer Organization. Computer organization is the part that is closely related to operational units. Example: Technology hardware, interface devices, memory technology, system memory, and control signal s.

processing giving out processed data. Therefore, the input unit takes data from us to the computer in an organized manner for processing. 1) It accepts data or instruction 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: This is the process of entering data and programs in to the computer system. You should know that computer is an electronic machine like any other machine, which takes as input raw data and performs some 2. Storage: The process of saving data and instructions permanently is known as storage. Data has to be fed into the system before the actual processing starts. It is because the processing speed of Central Processing Unit (CPU) is so fast that the data has to be provided to CPU with the same speed. Therefore the data is first stored in the storage unit for faster access and processing. This storage unit or the primary storage of the computer system is designed to do the above functionality. It provides space for storing data and instructions. 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 processing. The Central Processing Unit (CPU) takes data and instructions from the storage unit and makes all sorts of calculations based on the instructions given and the type of data provided. The result is then sent back to the storage unit. 36

4. Output: This is the process of producing results from the data for getting useful information. The results could either be displayed on the screen or may be printed for future reference. The output unit therefore allows the results to be either stored inside the computer for further processing or may give you the results in human readable form. 5. Control: The process of input, output, processing and storage is performed under the supervision of a unit called ‘Control Unit’. It decides when to start receiving data, when to stop it, where to store data, etc. It takes care of step-by-step processing of all operations inside the computer. FUNCTIONAL UNITS (CPU)

In order to carry out the operations mentioned in the previous section the computer allocates the task between its various functional units. The computer system is divided into three separate units for its operation. These are: • Arithmetic ogical Unit, • Control unit, and • Central processing unit. a) Control Unit (CU) This unit controls the operations of all parts of computer but does not carry out any actual data processing operations. Functions of this unit are: • It is responsible for controlling the transfer of data and instructions among other units of a computer. • It manages and coordinates all the units of the computer. • It obtains the instructions from the memory, interprets them, and directs the operation of the computer. • It communicates with Input/Output devices for transfer of data or results from storage. • It does not process or store data. b) Arithmetic Logical Unit (ALU) Arithmetic Section: Function of arithmetic section is to perform arithmetic operations like addition, subtraction, multiplication and division. All complex operations are done by making repetitive use of above operations. Logic Section: Function of logic section is to perform logic operations such as comparing, selecting, matching and merging of data. 37

c) Memory Unit This unit can store instructions, data and intermediate results. This unit supplies information to the other units of the computer when needed. It is also known as internal storage unit or main memory or primary storage or Random access memory(RAM). Its size affects speed, power and capability. Primary memory and secondary memory are two types of memories in the computer. Functions of memory unit are: • It stores all the data and the instructions required for processing. • It stores intermediate results of processing. • It stores final results of processing before these results are released to an output device. • All inputs and outputs are transmitted through main memory. Concept of System Buses: Basically, it is a means of getting data from one point to another, point A to point B, one device to another device, or one device to multiple devices. The bus includes not only the actual capability to transfer data between devices, but also all appropriate signaling information to ensure complete movement of the data from point A to point B. To avoid loss of data, a bus must include a means of controlling the flow of data between two devices, in order to insure that both devices are ready to send and/or receive information. Finally, both ends must understand the speed with which data is to be exchanged. A bus provides for all of these elements, and it includes a port definition to allow physical interfacing or connecting of two or more devices. The system bus consists of three types of buses: • Data Bus: Carries the data that needs processing • Address Bus: Determines where data should be sent • Control Bus: Determines data processing

Data Bus

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A data bus is a computer subsystem that allows for the transferring of data from one component to another on a motherboard or system board, or between two computers. This can include transferring data to and from the memory, or from the central processing unit (CPU) to other components. Each one is designed to handle so many bits of data at a time. The amount of data a data bus can handle is called bandwidth. A typical data bus is 32-bits wide. This means that up to 32 bits of data can travel through a data bus every second. Newer computers are making data buses that can handle 64-bit and even 96-bit data paths. At the same time they are making data buses to handle more bits, they are also making devices that can handle those higher bitrates.

Address bus

An address bus is a computer bus (a series of lines connecting two or more devices) that is used to specify a physical address. A collection of wires connecting the CPU with main memory that is used to identify particular locations (addresses) in main memory. The width of the address bus (that is, the number of wires) determines how many unique memory locations can be addressed. Control Bus The control bus is used by the CPU to direct and monitor the actions of the other functional areas of the computer this manages the information flow between components indicating whether the operation is a read or a write and ensuring that the operation happens at the right time.

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UNIT VI Operating System

An operating system, or OS, is a software program that enables the computer hardware to communicate and operate with the computer software. Without a computer operating system, a computer would be useless. Operating Systems are resource managers. The main resource is computer hardware in the form of processors, storage, input/output devices, communication devices, and data. Some of the operating system functions are: implementing the user interface, sharing hardware among users, allowing users to share data among themselves, preventing users from interfering with one another, scheduling resources among users, facilitating input/output, recovering from errors, accounting for resource usage, facilitating parallel operations, organizing data for secure and rapid access, and handling network communications. Objectives of Operating Systems Modern Operating systems generally have following three major goals. Operating systems generally accomplish these goals by running processes in low privilege and providing service calls that invoke the operating system kernel in high-privilege state. • To hide details of hardware by creating abstraction An abstraction is software that hides lower level details and provides a set of higher-level functions. An operating system transforms the physical world of devices, instructions, memory, and time into virtual world that is the result of abstractions built by the operating system. There are several reasons for abstraction. First, the code needed to control peripheral devices is not standardized. Operating systems provide subroutines called device drivers that perform operations on behalf of programs for example, input/output operations. Second, the operating system introduces new functions as it abstracts the hardware. For instance, operating system introduces the file abstraction so that programs do not have to deal with disks. Third, the operating system transforms the computer hardware into multiple virtual computers, each belonging to a different program. Each program that is running is called a process. Each process views the hardware through the lens of abstraction.

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Fourth,

the operating system can enforce security through abstraction.

•

To allocate resources to processes (Manage resources) An operating system controls how processes (the active agents) may access resources (passive entities). • Provide a pleasant and effective user interface The user interacts with the operating systems through the user interface and usually interested in the "look and feel" of the operating system. The most important components of the user interface are the command interpreter, the file system, on-line help, and application integration. The recent trend has been toward increasingly integrated graphical user interfaces that encompass the activities of multiple processes on networks of computers. One can view Operating Systems from two points of views: Resource manager and Extended machines. Form Resource manager point of view Operating Systems manage the different parts of the system efficiently and from extended machines point of view Operating Systems provide a virtual machine to users that is more convenient to use. The structurally Operating Systems can be design as a monolithic system, a hierarchy of layers, a virtual machine system, using the client-server model. The basic concepts of Operating Systems are processes, memory management, I/O management, the file systems, and security.

Process Management The operating system manages many kinds of activities ranging from user programs to system programs like printer spooler, name servers, file server etc. Each of these activities is encapsulated in a process. A process includes the complete execution context (code, data, PC, registers, OS resources in use etc.). It is important to note that a process is not a program. A process is only ONE instant of a program in execution. There are many processes can be running the same program. The five major activities of an operating system in regard to process management are • Creation and deletion of user and system processes. • Suspension and resumption of processes. • A mechanism for process synchronization. • A mechanism for process communication. • A mechanism for deadlock handling. Main-Memory Management Primary-Memory or Main-Memory is a large array of words or bytes. Each word or byte has its own address. Main-memory provides storage that can be access directly by the CPU. That is to say for a program to be executed, it must in the main memory. The major activities of an operating in regard to memory-management are: • Keep track of which part of memory are currently being used and by whom. • Decide which process are loaded into memory when memory space becomes available. • Allocate and deallocate memory space as needed.

File Management A file is a collected of related information defined by its creator. 41 Computer can store files on the disk (secondary storage),

which provide long term storage. Some examples of storage media are magnetic tape, magnetic disk and optical disk. Each of these media has its own properties like speed, capacity, data transfer rate and access methods. A file systems normally organized into directories to ease their use. These directories may contain files and other directions. The five main major activities of an operating system in regard to file management are 1. The creation and deletion of files. 2. The creation and deletion of directions. 3. The support of primitives for manipulating files and directions. 4. The mapping of files onto secondary storage. 5. The backup of files on stable storage media. I/O System Management I/O subsystem hides the peculiarities of specific hardware devices from the user. Only the device driver knows the peculiarities of the specific device to whom it is assigned. Secondary-Storage Management Generally speaking, systems have several levels of storage, including primary storage, secondary storage and cache storage. Instructions and data must be placed in primary storage or cache to be referenced by a running program. Because main memory is too small to accommodate all data and programs, and its data are lost when power is lost, the computer system must provide secondary storage to back up main memory. Secondary storage consists of tapes, disks, and other media designed to hold information that will eventually be accessed in primary storage (primary, secondary, cache) is ordinarily divided into bytes or words consisting of a fixed number of bytes. Each location in storage has an address; the set of all addresses available to a program is called an address space. The three major activities of an operating system in regard to secondary storage management are: 1. Managing the free space available on the secondary-storage device. 2. Allocation of storage space when new files have to be written. 3. Scheduling the requests for memory access.

Networking A distributed systems is a collection of processors that do not share memory, peripheral devices, or a clock. The processors communicate with one another through communication lines called network. The communication- network design must consider routing and connection strategies, and the problems of contention and security. Protection System If a computer systems has multiple users and allows the concurrent execution of multiple processes, then the various processes must be protected from one another's activities. Protection refers to mechanism for controlling the access of programs, processes, or users to the resources defined by a computer systems. Command Interpreter System A command interpreter is an interface of the operating system with the user. The user gives commands with are executed by operating system (usually by turning them into system calls). The main function of a command interpreter is to get and execute the next user specified command. Command-Interpreter is usually not part of the kernel, since multiple command interpreters (shell, in UNIX terminology) may be support by an operating system, and they do not really need to run in kernel mode. There are two main advantages to separating the command interpreter from the kernel. 1. If we want to change the way the command interpreter looks, i.e., I want to change the interface of command interpreter, I am able to do that if the command interpreter is separate from the kernel. I cannot change the code of the kernel so I cannot modify the interface. 2. If the command interpreter is a part of the kernel it is possible for a malicious process to gain access to certain part of the kernel that it showed not have to avoid this ugly scenario it is advantageous to have the command interpreter separate from kernel.

Features Operating Systems Following are the five services provided by an operating systems to the convenience of the users. Program Execution 42

The purpose of a computer systems is to allow the user to execute programs. So the operating systems provides an environment where the user can conveniently run programs. The user does not have to worry about the memory allocation or multitasking or anything. These things are taken care of by the operating systems. Running a program involves the allocating and deallocating memory, CPU scheduling in case of multiprocess. These functions cannot be given to the userlevel programs. So user-level programs cannot help the user to run programs independently without the help from operating systems. I/O Operations Each program requires an input and produces output. This involves the use of I/O. The operating systems hides the user the details of underlying hardware for the I/O. All the user sees is that the I/O has been performed without any details. So the operating systems by providing I/O makes it convenient for the users to run programs. For efficiently and protection users cannot control I/O so this service cannot be provided by user-level programs. File System Manipulation The output of a program may need to be written into new files or input taken from some files. The operating systems provides this service. The user does not have to worry about secondary storage management. User gives a command for reading or writing to a file and sees his her task accomplished. Thus operating systems makes it easier for user programs to accomplished their task. This service involves secondary storage management. The speed of I/O that depends on secondary storage management is critical to the speed of many programs and hence I think it is best relegated to the operating systems to manage it than giving individual users the control of it. It is not difficult for the user-level programs to provide these services but for above mentioned reasons it is best if this service s left with operating system. Communications There are instances where processes need to communicate with each other to exchange information. It may be between processes running on the same computer or running on the different computers. By providing this service the operating system relieves the user of the worry of passing messages between processes. In case where the messages need to be passed to processes on the other computers through a network it can be done by the user programs. The user program may be customized to the specifics of the hardware through which the message transits and provides the service interface to the operating system. Error Detection An error is one part of the system may cause malfunctioning of the complete system. To avoid such a situation the operating system constantly monitors the system for detecting the errors. This relieves the user of the worry of errors propagating to various part of the system and causing malfunctioning. This service cannot allowed to be handled by user programs because it involves monitoring and in cases altering area of memory or de-allocation of memory for a faulty process or may be relinquishing the CPU of a process that goes into an infinite loop. These tasks are too critical to be handed over to the user programs. A user program if given these privileges can interfere with the correct (normal) operation of the operating systems.

Types of Operating Systems An operating system is a software component of a computer system that is responsible for the management of various activities of the computer and the sharing of computer resources. It hosts several applications that run on a computer and handles the operations of computer hardware. Users and application programs access the services offered by the operating systems, by means of system calls and application programming interfaces. Users interact with a computer operating system through Command Line Interfaces (CLIs) or Graphical User Interfaces known as GUIs. In short, an operating system enables user interaction with computer systems by acting as an interface between users or application programs and the computer hardware. Here is an overview of the different types of operating systems. Networking operating system A network operating system is an operating system designed for the sole purpose of supporting workstations, database sharing, application sharing and file and printer access sharing among multiple computers in a network. Certain standalone operating systems, such as Microsoft Windows NT and Digital’s OpenVMS, come with multipurpose capabilities and can also act as network operating systems. Some of the most well-known network operating systems include Microsoft Windows Server 2003, Microsoft Windows Server 2008, Linux and Mac43OS X.

Real-time Operating System: Real-time systems are usually used to control complex systems that require a lot of processing like machinery and industrial systems. It is a multitasking operating system that aims at executing realtime applications. Real- time operating systems often use specialized scheduling algorithms so that they can achieve a deterministic nature of behavior. The main object of real-time operating systems is their quick and predictable response to events. They either have an event-driven or a time-sharing design. An event-driven system switches between tasks based of their priorities while time- sharing operating systems switch tasks based on clock interrupts. Multi-user and Single-user Operating Systems: Computer operating systems of this type allow multiple users to access a computer system simultaneously. Time-sharing systems can be classified as multi-user systems as they enable a multiple user access to a computer through time sharing. Single-user operating systems, as opposed to a multi-user operating system, are usable by only one user at a time. Being able to have multiple accounts on a Windows operating system does not make it a multi-user system. Rather, only the network administrator is the real user. But for a Unix-like operating system, it is possible for two users to login at a time and this capability of the OS makes it a multi-user operating system. This type of operating system is seen everywhere today and is the most common type of OS, the Windows operating system would be an example. Multi-tasking and Single-tasking Operating Systems: When a single program is allowed to run at a time, the system is grouped under the single-tasking system category, while in case the operating system allows for execution of multiple tasks at a time, it is classified as a multi-tasking operating system. Multi-tasking can be of two types namely, pre-emptive or cooperative. In pre-emptive multitasking, the operating system slices the CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and Linux support preemptive multitasking. If you are aware of the multi-threading terminology, you can consider this type of multitasking as similar to interleaved multi-threading. Cooperative multitasking is achieved by relying on each process to give time to the other processes in a defined manner. This kind of multi-tasking is similar to the idea of block multi-threading in which one thread runs till it is blocked by some other event. MS Windows prior to Windows 95 used to support cooperative multitasking. Distributed Operating System: In a distributed system, software and data maybe distributed around the system, programs and files maybe stored on different storage devices which are located in different geographical locations and maybe accessed from different computer terminals. The development of networked computers that could be linked and made to communicate with each other, gave rise to distributed computing. Distributed computations are carried out on more than one machine. When computers in a group work in cooperation, they make a distributed system. Embedded System: The operating systems designed for being used in embedded computer systems are known as embedded operating systems. They are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources. They are very compact and extremely efficient by design. Windows CE, FreeBSD ect. are some examples of embedded operating systems. Mobile Operating System: Though not a functionally distinct kind of operating system, mobile OS is definitely an important mention in the list of operating system types. A mobile OS controls a mobile device and its design supports wireless communication and mobile applications. It has built-in support for mobile multimedia formats. Tablet PCs and smart-phones run on mobile operating systems. Batch Processing and Interactive Systems: Batch processing refers to execution of computer programs in 'batches' without manual intervention. In batch processing systems, programs are collected, grouped and processed on a later date. There is no prompting the user for inputs as input data are collected in advance for future processing. Input data are collected and processed in batches, hence the name batch processing. IBM's z/OS has batch processing capabilities. As against this, interactive operating requires user intervention. The process cannot be executed in the user's absence. Online and Offline Processing: In online processing of data, the user remains in contact with the computer and processes are executed under control of the computer's central processing unit. When processes are not executed under direct control of the CPU, the processing is referred to as offline. Let's take the example of batch processing. Here, the batching or grouping of data can be done without user and CPU intervention; it can be done offline. But the actual process execution may happen under direct control of the processor, that is online. 44

Operating systems contribute to simplifying human interaction with the computer hardware. They are responsible for linking application programs with the hardware, thus achieving easy user access to computers. Ever imagined a computer without an OS? It wouldn't be so user-friendly then!

Operating System Based on User Interface Every computer that is to be operated by an individual requires a user interface. The user interface is not actually a part of the operating system—it generally runs in a separate program usually referred to as a shell, but is essential if human interaction is to be supported. The user interface requests services from the operating system that will acquire data from input hardware devices, such as a keyboard, mouse or credit card reader, and requests operating system services to display prompts, status messages and such on output hardware devices, such as a video monitor or printer. The two most common forms of a user interface have historically been the command-line interface, where computer commands are typed out line-by-line, and the graphical user interface, where a visual environment is present. i) Command-line interface A command-line interface (CLI) is a mechanism for interacting with a computer operating system or software by typing commands to perform specific tasks. This text-only interface contrasts with the use of a mouse pointer with a graphical user interface (GUI) to click on options, or menus on a text user interface (TUI) to select options. This method of instructing a computer to perform a given task is referred to as "entering" a command: the system waits for the user to conclude the submitting of the text command by pressing the "Enter" key (a descendant of the "carriage return" key of a typewriter keyboard). A commandline interpreter then receives, parses, and executes the requested user command. Upon completion, the command usually returns output to the user in the form of text lines on the CLI. This output may be an answer if the command was a question, or otherwise a summary of the operation. ii) Graphical user interface A graphical user interface (GUI) is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and office equipment. A GUI represents the information and actions available to a user through graphical icons and visual indicators such as secondary notation, as opposed to text-based interfaces, typed command labels or text navigation. The actions are usually performed through direct manipulation of the graphical elements.

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UNIT VII

Computer Network A computer network is a set of computers or devices that are connected with each other to carry on data and share information. In computing, it is called a network as a way to interconnect two or more devices to each other using cables, signals, waves or other methods with the ultimate goal of transmitting data, share information, resources and services.

Purpose of networking: The purpose of a network is, generally, to facilitate and expedite communications between two or more instances on the same physical space or connected remotely. Such systems also allow cost savings and time. The most known type of network is the Intranet, which is a private network that uses Internet as a basic architecture in order to connect various devices. Internet, however, is a technology that connects devices throughout the world, and that is why it is called “network of networks.” Classifications of Networks: The networks are classified by range (personal, local, campus, metropolitan or wide area), as well as by method of connection (cable, fiber optics, radio, infrared, wireless, etc..) or by functional relationship (client – server or peer‐to‐peer). Also in the topology field there is a classification to be aware of (bus, star, ring, mesh, tree etc.) and directional (simplex, half duplex or full duplex). Use of a network: The use of a network in an office, for example, in which all employees have the same access to resources such as programs and applications or devices like a printer or scanner. Moreover, configuring a large‐scale network facilitates communication among different geographic locations, so a company with multiple branches in the world can keep in communication with its members in a simple and quick. Finally, a network can be used as a home to share files or maximize the available space. Pros and Cons of Networking (Advantages and Disadvantages of Network) Advantages of Computer Networking 1. Easy Communication and Speed It is very easy to communicate through a network. People can communicate efficiently using a network with a group of people. They can enjoy the benefit of emails, instant messaging, telephony, video conferencing, chat rooms, etc. 2. Ability to Share Files, Data and Information This is one of the major advantages of networking computers. People can find and share information and data because of networking. This is beneficial for large organizations to maintain their data in an organized manner and facilitate access for desired people. 3. Sharing Hardware Another important advantage of networking is the ability to share hardware. For an example, a printer can be shared among the users in a network so that there’s no need to have individual printers for each and every computer in the company. This will significantly reduce the cost of purchasing hardware. 46

4. Sharing Software Users can share software within the network easily. Networkable versions of software are available at considerable savings compared to individually licensed version of the same software. Therefore large companies can reduce the cost of buying software by networking their computers. 5. Security Sensitive files and programs on a network can be password protected. Then those files can only be accessed by the authorized users. This is another important advantage of networking when there are concerns about security issues. Also each and every user has their own set of privileges to prevent them accessing restricted files and programs. 6. Speed Sharing and transferring files within networks is very rapid, depending on the type of network. This will save time while maintaining the integrity of files. Disadvantages of Networking 1. Breakdowns and Possible Loss of Resources One major disadvantage of networking is the breakdown of the whole network due to an issue of the server. Such breakdowns are frequent in networks causing losses of thousands of dollars each year. Therefore once established it is vital to maintain it properly to prevent such disastrous breakdowns. The worst scenario is such breakdowns may lead to loss of important data of the server. 2. Expensive to Build Building a network is a serious business in many occasions, especially for large scale organizations. Cables and other hardware are very pricey to buy and replace. 3. Security Threats Security threats are always problems with large networks. There are hackers who are trying to steal valuable data of large companies for their own benefit. So it is necessary to take utmost care to facilitate the required security measures. 4. Bandwidth Issues In a network there are users who consume a lot more bandwidth than others. Because of this some other people may experience difficulties. Although there are disadvantages to networking, it is a vital need in today’s environment. People need to access the Internet, communicate and share information and they can’t live without that. Therefore engineers need to find alternatives and improved technologies to overcome issues associated with networking. Therefore we can say that computer networking is always beneficial to have even if there are some drawbacks.

Types of Networks

There are several different types of computer networks. Computer networks can be characterized by their size as well as their purpose. The size of a network can be expressed by the geographic area they occupy and the number of computers that are part of the network. Networks can cover anything from a handful of devices within a single room to millions of devices spread across the entire globe. Some of the different networks based on size are: • Personal area network, or PAN • Campus Area Network (CAN) • Local area network, or LAN • Metropolitan area network, or MAN • Wide area network, or WAN 47

Personal Area Network (PAN)

A personal area network, or PAN, is a computer network organized around an individual person within a single building. This could be inside a small office or residence. A typical PAN would include one or more computers, telephones, peripheral devices, video game consoles and other personal entertainment devices. If multiple individuals use the same network within a residence, the network is sometimes referred to as a home area network, or HAN. In a very typical setup, a residence will have a single wired Internet connection connected to a modem. This modem then provides both wired and wireless connections for multiple devices. The network is typically managed from a single computer but can be accessed from any device. This type of network provides great flexibility. For example, it allows you to: • Send a document to the printer in the office upstairs while you are sitting on the couch with your laptop. • Upload the photo from your cell phone to your desktop computer. • Watch movies from an online streaming service to your TV. Campus Area Network (CAN)

A Campus Area Network (CAN) is a computer network that links the buildings and consists of two or more local area networks (LANs) within the limited geographical area. It can be the college campus, enterprise campus, office buildings, military base, and industrial complex. CAN is one of the type of MAN (Metropolitan Area Network) on the area smaller than MAN. Local Area Network (LAN): A local area network (LAN) is a computer network that connects computers and devices in a limited geographical area such as home, school, computer laboratory or office building. The defining characteristics of LANs, in contrast to wide area networks (WANs), include their usually higher data transfer rates, smaller geographic area, and lack of a need for leased 48

telecommunication lines. The Local Area Network is also referred as LAN. This system spans on a small area like a small office or home. The computer systems are linked with cables. In LAN system computers on the same site could be linked. Metropolitan area network (MAN):

A metropolitan area network (MAN) is a computer network that usually spans a city or a large campus. A MAN usually interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks (or WAN) and the Internet. Wide Area Network (WAN):

A wide area network (WAN) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries). This is in contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a 49

room, building, campus or specific metropolitan area (e.g., a city) respectively. A Wide Area Network or WAN is a type of networking where a number of resources are installed across a large area such as multinational business. Through WAN offices in different countries can be interconnected. The best example of a WAN could be the Internet that is the largest network in the world. In WAN computer systems on different sites can be linked.

Network topology Network topology is the layout pattern of interconnections of the various elements (links, nodes, etc.) of a computer network. Network topologies may be physical or logical. Physical topology refers to the physical design of a network including the devices, location and cable installation. Logical topology refers to how data is actually transferred in a network as opposed to its physical design. In general physical topology relates to a core network whereas logical topology relates to basic network. Topology can be understood as the shape or structure of a network. This shape does not necessarily correspond to the actual physical design of the devices on the computer network. The computers on a home network can be arranged in a circle but it does not necessarily mean that it represents a ring topology. Bus Topology: In local area networks where bus topology is used, each node is connected to a single cable. Each computer or server is connected to the single bus cable. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data does match the machine address, the data is accepted. Since the bus topology consists of only one wire, it is rather inexpensive to implement when compared to other topologies. However, the low cost of implementing the technology is offset by the high cost of managing the network. Additionally, since only one cable is utilized, it can be the single point of failure. If the network cable breaks, the entire network will be down.

Advantages • Easy to implement and extend. • Easy to install. • Well-suited for temporary or small networks not requiring high speeds (quick setup), resulting in faster networks. • Less expensive than other topologies (But in recent years has become less important due to devices like a switch) • Cost effective; only a single cable is used. • Easy identification of cable faults. Disadvantages • Limited cable length and number of stations. • If there is a problem with the cable, the entire network breaks down. • Maintenance costs may be higher in the long run. • Performance degrades as additional computers are added or on heavy traffic (shared bandwidth). • Proper termination is required (loop must be in closed path). • Significant Capacitive Load (each bus transaction must be able to stretch to most distant link). 50

• It works best with limited number of nodes. • Commonly has a slower data transfer rate than other topologies. • Only one packet can remain on the bus during one clock pulse Star Topology: Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages. This consists of a central node, to which all other nodes are connected; this central node provides a common connection point for all nodes through a hub.

Advantages • Better performance: star topology prevents the passing of data packets through an excessive number of nodes. At most, 3 devices and 2 links are involved in any communication between any two devices. Although this topology places a huge overhead on the central hub, with adequate capacity, the hub can handle very high utilization by one device without affecting others. • Isolation of devices: Each device is inherently isolated by the link that connects it to the hub. This makes the isolation of individual devices straightforward and amounts to disconnecting each device from the others. This isolation also prevents any non-centralized failure from affecting the network. • Benefits from centralization: As the central hub is the bottleneck, increasing its capacity, or connecting additional devices to it, increases the size of the network very easily. Centralization also allows the inspection of traffic through the network. This facilitates analysis of the traffic and detection of suspicious behavior. • Easy to detect faults and to remove parts. • No disruptions to the network when connecting or removing devices. Disadvantages • High dependence of the system on the functioning of the central hub • Failure of the central hub renders the network inoperable

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Ring Topology: A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring. Data travels from node to node, with each node along the way handling every packet. Because a ring topology provides only one pathway between any two nodes, ring networks may be disrupted by the failure of a single link. A node failure or cable break might isolate every node attached to the ring.

Advantages • Very orderly network where every device has access to the token and the opportunity to transmit • Performs better than a bus topology under heavy network load • Does not require network server to manage the connectivity between the computers Disadvantages • One malfunctioning workstation can create problems for the entire network • Moves, adds and changes of devices can affect the network • Network adapter cards much more expensive than Ethernet cards and hubs • Much slower than an Ethernet network under normal load Tree Topology: The type of network topology in which a central 'root' node (the top level of the hierarchy) is connected to one or more other nodes that are one level lower in the hierarchy (i.e., the second level) with a point-to point link between each of the second level nodes and the top level central 'root' node, while each of the second level nodes that are connected to the top level central 'root' node will also have one or more other nodes that are one level lower in the hierarchy (i.e., the third level) connected to it, also with a point-to-point link, the top level central 'root' node being the only node that has no other node above it in the hierarchy (The hierarchy of the tree is symmetrical.) Each node in the network having a specific fixed Number, of nodes connected to it at the next lower level in the hierarchy, the number, being referred to as the 'branching factor' of the hierarchical tree. This tree has individual peripheral nodes. A network that is based upon the physical hierarchical topology must have at least three levels in the hierarchy of the tree, since a network with a central 'root' node and only one hierarchical level below it would exhibit the physical topology of a star. 52

Advantages • It is the best topology for a large computer network for which a star topology or ring topology are unsuitable due to the sheer scale of the entire network. Tree topology divides the whole network into parts that are more easily manageable. • Tree topology makes it possible to have a point to point network. • All computers have access to their immediate neighbors in the network and also the central hub. This kind of network makes it possible for multiple network devices to be connected with the central hub. • It overcomes the limitation of star network topology, which has a limitation of hub connection points and the broadcast traffic induced limitation of a bus network topology. • A tree network provides enough room for future expansion of a network. Tree topology disadvantages • Dependence of the entire network on one central hub is a point of vulnerability for this topology. A failure of the central hub or failure of the main data trunk cable, can cripple the whole network. • With increase in size beyond a point, the management becomes difficult. Mesh Topology: A mesh network can be designed using a flooding technique or a routing technique. When using a routing technique, the message propagates along a path, by hopping from node to node until the destination is reached. To ensure all its paths' availability, a routing network must allow for continuous connections and reconfiguration around broken or blocked paths, using self-healing algorithms. A mesh network whose nodes are all connected to each other is a fully connected network. Mesh networking (topology) is a type of networking where each node must not only capture and disseminate its own data, but also serve as a relay for other sensor nodes, that is, it must collaborate to propagate the data in the network.

Advantages of Mesh Topology • There are dedicated links used in the topology, which guarantees, that each connection is able to carry its data load, thereby eliminating traffic problems, which are common, when links are shared by multiple devices. • It is a robust topology. When one link in the topology becomes unstable, it does not cause the entire system to halt. • If the network is to be expanded, it can be done without causing any disruption to current users of the network. 53

• It is possible to transmit data, from one node to a number of other nodes simultaneously • Troubleshooting, in case of a problem, is easy as compared to other network topologies. • This topology ensures data privacy and security, as every message travels along a dedicated link. Disadvantages of Mesh Topology • The first disadvantage of this topology is that, it requires a lot more hardware (cables, etc.) as compared to other Local Area Network (LAN) topologies. • The implementation (installation and configuration) of this topology is very complicated and can get very messy. A large number of Input / Outout (I/O) ports are required. • It is an impractical solution, when large number of devices are to be connected to each other in a network. • The cost of installation and maintenance is high, which is a major deterrent. Hybrid network topology

Hybrid network topology is a combination of two or more different basic network topologies. For example, it can be starring, star-bus topologies, etc. It must be certainly different topologies, because for example two star topologies form the star topology. The resulting hybrid topology has the features and limitations of its components. Hybrid network topology has many advantages. Hybrid topologies are flexible, reliable, have increased fault tolerance. The new nodes can be easily added to the hybrid network, the network faults can be easily diagnosed and corrected without affecting the work of the rest of network. But at the same time hybrid topologies are expensive and difficult for managing.

Guided media and Unguided media Guided Media or Wired links or Bound media Guided Transmission Media uses a cabling system that guides the data signals along a specific path . The data signals are bound by the cabling system. Guided Media is also known as Bound Media or Wired media. There are three basic types of Guided Media: 1. Twisted Pair 2. Coaxial Cable 3. Optical Fiber 1. Twisted Pair Cable Twisted pair cable consists of a pair of insulated wires twisted together. It is a cable type used in telecommunication for very long time. Cable twisting helps to reduce noise pickup from outside sources and crosstalk on multi-pair cables. The most commonly used form of twisted pair is unshielded twisted pair (UTP). It is just two insulated wires twisted together. Any data communication cables and normal telephone cables are this type. Shielded twisted pair (STP) differs from UTP in that it has a foil jacket that helps prevent crosstalk and noise from outside source. In data communications there is a cable type called FTP (foil shielded pairs) which consists of four twisted pair inside one common shield (made of aluminum foil).

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2. Coaxial Cable Coaxial cables are a type of cable that is used by cable TV and that is common for data communications. Taking an around cross-section of the cable, one would find a single center solid wire symmetrically surrounded by a braided or foil conductor. Between the center wire and foil is a insulating dielectric. This dielectric has a large effect on the fundamental characteristics of the cable. In this lab, we show the how the permittivity and permeability of the dielectric contributes to the cable's inductance and capacitance. Also, these values affect how quickly electrical data is travels through the wire. Data is transmitted through the center wire, while the outer braided layer serves as a line to ground. Both of these conductors are parallel and share the same axis. This is why the wire is called coaxial

3. Optical Fiber Optical fiber (or "fiber optic") refers to the medium and the technology associated with the transmission of information as light pulses along a glass or plastic strand or fiber. Optical fiber carries much more information than conventional copper wire and is in general not subject to electromagnetic interference and the need to retransmit signals. Most telephone company long-distance lines are now made of optical fiber. Transmission over an optical fiber cable requires repeaters at distance intervals. The glass fiber requires more protection within an outer cable than copper. For these reasons and because the installation of any new cabling is labor-intensive, few communities have installed optical fiber cables from the phone company's branch office to local customers (known as local loops). A type of fiber known as single mode fiber is used for longer distances; multimode fiber is used for shorter distances.

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Unbound Media or Unguided Media:

Unguided Media: It is one that does not guide the data signals instead it uses the multiple paths for transmitting data signals. In this type the data cable are not bounds to a cable media. So it is called “Unbound media” basically there are 2 types. a) Microwave b) Satellite Technology. a) Microwave:

Microwaves are radio waves that are used to provide high‐speed transmission. Both voice and data can be transmitted through microwave. Data is transmitted through the air form one microwave station to other similar to radio signals. Microwave uses line‐of‐sight transmission. It means that the signals travel in straight path and cannot bend. Microwave stations or antennas are usually installed on high towers or buildings. Microwave stations are placed within 20 to 30 miles to each other. Each station receives signal from previous station and transfer to next station. In this way, data transferred from one place to another. There should be no buildings on mountains between microwave stations.

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b) Satellite Communication:

Communication satellite is a space station. It receives microwave signals from earth station. It amplifies the signal and retransmits them back to earth. Communication satellite is established in space about 22,300 miles above the earth. The data transfer speed of communication satellite is very high. The transmission from earth station to satellite is called uplink. The transmission from satellite to earth station is called downlink. An important advantage at satellite is that a large volume of data can be communicated at once. The disadvantage is that bad weather can severely affect the quality of satellite transmission.

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Communication Protocol

A communications protocol is a formal description of digital message formats and the rules for exchanging those messages in or between computing systems and in telecommunications. Protocols may include signaling, authentication and error detection and correction capabilities. A protocol defines the syntax, semantics, and synchronization of communication, and the specified behaviour is typically independent of how it is to be implemented. A protocol can therefore be implemented as hardware or software or both. Communicating systems use well‐defined formats for exchanging messages. Each message has an exact meaning intended to provoke a defined response of the receiver. A protocol therefore describes the syntax, semantics, and synchronization of communication. The layering scheme in use on the Internet is called the TCP/IP model. The actual protocols are collectively called the Internet protocol suite. The group responsible for this design is called the Internet Engineering Task Force (IETF).

TCP/IP

TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). TCP/IP is a two‐layer program. The higher layer, Transmission Control Protocol, manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer, Internet Protocol, handles the address part of each packet so that it gets to the right destination. Each gateway computer on the network checks this address to see where to forward the message. Even though some packets from the same message are routed differently than others, they'll be reassembled at the destination. As with all other communications protocol, TCP/IP is composed of layers: • IP ‐ is responsible for moving packet of data from node to node. IP forwards each packet based on a four byte destination address (the IP number). The Internet authorities assign ranges of numbers to different organizations. The organizations assign groups of their numbers to departments. IP operates on gateway machines that move data from department to organization to region and then around the world. • TCP ‐ is responsible for verifying the correct delivery of data from client to server. Data can be lost in the intermediate network. TCP adds support to detect errors or lost data and to trigger retransmission until the data is correctly and completely received.

IP addresses (IPv4 and IPv6)

Every machine on a network has a unique identifier. Just as you would address a letter to send in the mail, computers use the unique identifier to send data to specific computers on a network. Most networks today, including all computers on the Internet, use the TCP/IP protocol as the standard for how to communicate on the network. In the TCP/IP protocol, the unique identifier for a computer is called its IP address. There are two standards for IP addresses: (1) IP Version 4 (IPv4) (2) IP Version 6 (IPv6)

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IP Version 4 (IPv4)

In IPv4 an address consists of 32 bits which limits the address space to 4294967296 (232) possible unique addresses. IPv4 reserves some addresses for special purposes such as private networks or multicast addresses. IPv4 addresses are basically represented in dot-decimal notation, which consists of four decimal numbers, each ranging from 0 to 255, separated by dots, e.g., 172.16.254.1. Each part represents a group of 8 bits (octet) of the address. IP Version 6 (IPv6)

The rapid exhaustion of IPv4 address space prompted the Internet Engineering Task Force (IETF) to explore new technologies to expand the addressing capability in the Internet. The permanent solution was deemed to be a redesign of the Internet Protocol itself. This new generation of the Internet Protocol was eventually named Internet Protocol Version 6 (IPv6) in 1995. The address size was increased from 32 to 128 bits, providing up to 2128 (approximately 3.403×1038) addresses. This is deemed sufficient for the foreseeable future. The large number of IPv6 addresses allows large blocks to be assigned for specific purposes. All modern desktop and enterprise server operating systems include native support for the IPv6 protocol, but it is not yet widely deployed in other devices, such as residential networking routers, voice over IP (VoIP) and multimedia equipment, and network peripherals.

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Computer Software and Classification Computer software, or just software, is a collection of computer programs and related data that provide the instructions for telling a computer what to do and how to do it. In other words, software is a conceptual entity which is a set of computer programs, procedures, and associated documentation concerned with the operation of a data processing system. We can also say software refers to one or more computer programs and data held in the storage of the computer for some purposes. In other words software is a set of programs, procedures, algorithms and its documentation. Program software performs the function of the program it implements, either by directly providing instructions to the computer hardware or by serving as input to another piece of software. In contrast to hardware, software "cannot be touched". ■ ■ ■ ■ ■

Application software Middleware Programming languages System software Firmware

Types of software

Application software Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with documents. Apps may be bundled with the computer and its system software, or may be published separately. Some users are satisfied with the bundled apps and need never install one. Practical: MS-Word, MS-Excel and MS-PowerPoint

Utility software, Utility software helps to manage, maintain and control computer resources. Operating systems typically contain the necessary tools for this, but separate utility programs can provide improved functionality. Utility software is often somewhat technical and targeted at users with a solid knowledge of computers.

Middleware Middleware is computer software components or people and their applications. The software consists of a set of services that allows multiple processes running on one or more machines to interact. This technology evolved to provide for interoperability in support of the move to coherent distributed architectures, which are most often used to support and simplify complex distributed applications. It includes web servers, application servers, and similar tools that support application development and delivery. Middleware is especially integral to modern information technology based on XML, SOAP, Web services, and service-oriented architecture. 60

Programming languages A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely. System software System software is computer software designed to operate the computer hardware and to provide a platform for running application software. The most basic types of system software are: The operating system (prominent examples being Microsoft Windows, Mac OS X and Linux), which allows the parts of a computer to work together by performing tasks like transferring data between memory and disks or rendering output onto a display device. It also provides a platform to run high-level system software and application software. Servers, in this context, are computer programs running to serve the requests of other programs, the "clients". The server performs some computational task on behalf of clients which may run on either the same computer or on other computers connected through a network. Window systems are components of a graphical user interface (GUI), and more specifically of a desktop environment, which supports the implementation of window managers, and provides basic support for graphics hardware, pointing devices such as mice, and keyboards. The mouse cursor is also generally drawn by the windowing system. In some publications, the term system software is also used to designate software development tools (like a compiler, linker or debugger). Firmware In electronic systems and computing, firmware is a term often used to denote the fixed, usually rather small, programs and/or data structures that internally control various electronic devices. Typical examples of devices containing firmware range from end-user products such as remote controls or calculators, through computer parts and devices like hard disks, keyboards, TFT screens or memory cards, all the way to scientific instrumentation and industrial robotics. Also more complex consumer devices, such as mobile phones, digital cameras, synthesizers, etc., contain firmware to enable the device's basic operation as well as implementing higher-level functions.

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UNIT IX Utility software Utility software helps to manage, maintain and control computer resources. Operating systems typically contain the necessary tools for this, but separate utility programs can provide improved functionality. Utility software is often somewhat technical and targeted at users with a solid knowledge of computers. •

 

The Device Manager is a Control Panel applet in Microsoft Windows operating systems. It allows users to view and control the hardware attached to the computer. When a piece of hardware is not working, the offending hardware is highlighted for the user to deal with. The list of hardware can be sorted by various criteria. For each device, users can: Supply device drivers Enable or disable devices Tell Windows to ignore malfunctioning devices View other technical properties

• • • •

Anti-virus utilities scan for computer viruses. Data compression utilities output a shorter stream or a smaller file when provided with a stream or file. Disk checkers can scan operating hard drive. Disk cleaners can find files that are unnecessary to computer operation, or take up considerable amounts of

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Disk compression utilities can transparently compress/uncompressed the contents of a disk, increasing the

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Disk defragmenters can detect computer files whose contents are scattered across several locations on the

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Registry cleaners clean and optimize the Windows Registry by removing old registry keys that are no longer

  

space. Disk cleaner helps the user to decide what to delete when their hard disk is full. capacity of the disk. hard disk, and move the fragments to one location to increase efficiency. in use..

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spyware scanner, spyware scanner scans the spyware and clean from hard disk.

Device drivers In computing, a device driver (commonly referred to as a driver) is a computer program that operates or controls a particular type of device that is attached to a computer. A driver provides a software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions without needing to know precise details of the hardware being used. Language Translator This types of software translate the one language to another language. For example, Google translate (http://translate.google.com/) Computer Virus A computer virus is a computer program that can replicate itself and spread from one computer to another. The term "virus" is also commonly but erroneously used to refer to other types of malware, including but not limited to adware and spyware programs that do not have the reproductive ability. A true virus can spread from one computer to another (in some form of executable code) when its host is taken to the target computer; for instance because a user sent it over a network or the Internet, or carried it on a removable medium such as a floppy disk, CD, DVD, or USB drive. Viruses can increase their chances of spreading to other computers by infecting files on a network file system or a file system that is accessed by another computer. Types of Viruses Not all computer viruses behave, replicate, or infect the same way. There are several different categories of viruses and malware. Below I list and discuss some of the most common types of computer viruses.

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Trojan horse: A Trojan horse program has the appearance of having a useful and desired function. While it may advertise its activity after launching, this information is not apparent to the user beforehand. Secretly the program performs other, undesired functions. A Trojan horse neither replicates nor copies itself, but causes damage or compromises the security of the computer. A Trojan horse must be sent by someone or carried by another program and may arrive in the form of a joke program or software of some sort. The malicious functionality of a Trojan Horse may be anything undesirable for a computer user, including data destruction or compromising a system by providing a means for another computer to gain access, thus bypassing normal access controls. Worms: A worm is a program that makes and facilitates the distribution of copies of itself; for example, from one disk drive to another, or by copying itself using email or another transport mechanism. The worm may do damage and compromise the security of the computer. It may arrive via exploitation of system vulnerability or by clicking on an infected e-mail. Bootsector Virus: A virus which attaches itself to the first part of the hard disk that is read by the computer upon bootup. These are normally spread by floppy disks. Macro Virus: Macro viruses are viruses that use another application's macro programming language to distribute themselves. They infect documents such as MS Word or MS Excel and are typically spread to other similar documents. Memory Resident Viruses: Memory Resident Viruses reside in a computers volatile memory (RAM). They are initiated from a virus which runs on the computer and they stay in memory after it's initiating program closes. Rootkit Virus: A rootkit virus is an undetectable virus which attempts to allow someone to gain control of a computer system. The term rootkit comes from the linux administrator root user. These viruses are usually installed by Trojans and are normally disguised as operating system files. Polymorphic Viruses: A polymorphic virus not only replicates itself by creating multiple files of itself, but it also changes it's digital signature every time it replicates. This makes it difficult for less sophisticated antivirus software to detect. Logic Bombs/Time Bombs: These are viruses which are programmed to initiate at a specific date or when a specific event occurs. Some examples are a virus which deletes your photos on Halloween, or a virus which deletes a database table if a certain employee gets fired.

Spyware: "Spyware" is mostly classified into four types: system monitors, trojans, adware, and tracking cookies. Spyware is mostly used for the purposes of tracking and storing Internet users' movements on the Web and serving up pop-up ads to Internet users. Whenever spyware is used for malicious purposes, its presence is typically hidden from the user and can be difficult to detect. Some spyware, such as keyloggers, may be installed by the owner of a shared, corporate, or public computer intentionally in order to monitor users.

Anti-virus Anti-virus software that can detect and eliminate known viruses after the computer downloads or runs the executable. There are two common methods that an anti-virus software application uses to detect viruses. The first, and by far the most common method of virus detection is using a list of virus signature definitions. This works by examining the content of the computer's memory (its RAM, and boot sectors) and the files stored on fixed or removable drives (hard drives, floppy drives), and comparing those files against a database of known virus "signatures". The disadvantage of this detection method is that users are only protected from viruses that pre-date their last virus definition update. The second method is to use a heuristic algorithm to find viruses based on common behaviors. This method has the ability to detect novel viruses that anti-virus security firms have yet to create a signature for.

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UNIT X

Information Technology (IT)

Information technology (IT) is the use of any computers, storage, networking and other physical devices, infrastructure and processes to create, process, store, secure and exchange all forms of electronic data. Typically, IT is used in the context of enterprise operations as opposed to personal or entertainment technologies. The commercial use of IT encompasses both computer technology and telephony. IT includes several layers of physical equipment (hardware), virtualization and management or automation tools, operating systems and applications (software) used to perform essential functions. User devices, peripherals and software, such as laptops, smartphones or even recording equipment, can be included in the IT domain. IT can also refer to the architectures, methodologies and regulations governing the use and storage of data. Importance of IT Information technology pertains to the study, design, and development of computer systems (hardware and software) and networks, which are used for obtaining, processing, and distributing data. In the world of globalization, Information system is such where data are collected, classified and put into process interpreting the result thereon in order to provide an integrated series of information for further communicating and analyzing. In a progressively more spirited worldwide atmosphere, Information System plays the role as 'enabler and facilitator', which endows with tactical values to the officialdom and considerable step up to the excellence of administration. 'An Information System is a particular type of work system that uses information technology to detain, put on the air, store, retrieve, manipulate or display information, thereby partisan one or more other work structure'. Application of IT □Education Computers are extensively used, as a tool and as an aid, for imparting education. Educators use computers to prepare notes and presentations of their lectures. Computers are used to develop computer-based training packages, to provide distance education using the e-learning software, and to conduct online examinations. Researchers use computers to get easy access to conference and journal details and to get global access to the research material. □Entertainment Computers have had a major impact on the entertainment industry. The user can download and view movies, play games, chat, book tickets for cinema halls, use multimedia for making movies, incorporate visual and sound effects using computers, etc. The users can also listen to music, download and share music, create music using computers, etc. □ Sports A computer can be used to watch a game, view the scores, improve the game, play games (like chess, etc.) and create games. They are also used for the purposes of training players. □Advertising Computer is a powerful advertising media. Advertisement can be displayed on different websites, electronicmails can be sent and reviews of a product by different customers can be posted. Computers are also used to create an advertisement using the visual and the sound effects. For the advertisers, computer is a medium via which the advertisements can be viewed globally. Web advertising has become a significant factor in the marketing plans of almost all companies. In fact, the business model of Google is mainly dependent on web advertising for generating revenues. □Medicine Medical researchers and practitioners use computers to access information about the advances in medical research or to take opinion of doctors globally. The medical history of patients is stored in the computers. Computers are also an integral part of various kinds of sophisticated medical equipment like ultrasound machine, CAT scan machine, MRI scan machine, etc. Computers also provide assistance to the medical surgeons during critical surgery operations like laparoscopic operations, etc. □ Science and Engineering Scientists and engineers use computers for performing complex scientific calculations, for designing and making drawings (CAD/CAM applications) and also for simulating and testing the designs. Computers are used for storing the complex data, performing complex calculations and for visualizing 3-dimensional objects. Complex scientific applications like the launch of the rockets, space exploration, etc., are not possible without the computers. □ Government The government uses computers to manage its own operations and also for e- governance. The websites of 53

the different government departments provide information to the users. Computers are used for the fi ling of income tax return, paying taxes, online submission of water and electricity bills, for the access of land record details, etc. □Home Computers have now become an integral part of home equipment. At home, people use computers to play games, to maintain the home accounts, for communicating with friends and relatives via Internet, for paying bills, for education and learning, etc. Microprocessors are embedded in house hold utilities like, washing machines, TVs, food processors, home theatres, security devices, etc. The list of applications of computers is so long that it is not possible to discuss all of them here. In addition to the applications of the computers discussed above, computers have also proliferated into areas like banks, investments, stock trading, accounting, ticket reservation, military operations, meteorological predictions, social networking, business organizations, police department, video conferencing, book publishing, web newspapers, and information sharing.

Application Package

Word Processor A word processor, or word processing program, does exactly what the name implies. It processes words. It also processes paragraphs, pages, and entire papers. Some examples of word processing programs include Microsoft Word, WordPerfect (Windows only), AppleWorks (Mac only), and OpenOffice.org. The first word processors were basically computerized typewriters, which did little more than place characters on a screen, which could then be printed by a printer. Modern word processing programs, however, include features to customize the style of the text, change the page formatting, and may be able to add headers, footers, and page numbers to each page. Some may also include a "Word Count" option, which counts the words and characters within a document. Word processing Using a computer to create, edit, and print documents. Of all computer applications, word processing is the most common. To perform word processing, you need a computer, a special program called a word processor, and a printer. A word processor enables you to create a document, store it electronically on a disk, display it on a screen, modify it by entering commands and characters from the keyboard, and print it on a printer. The great advantage of word processing over using a typewriter is that you can make changes without retyping the entire document. If you make a typing mistake, you simply back up the cursor and correct your mistake. If you want to delete a paragraph, you simply remove it, without leaving a trace. It is equally easy to insert a word, sentence, or paragraph in the middle of a document. Word processors also make it easy to move sections of text from one place to another within a document, or between documents. When you have made all the changes you want, you can send the file to a printer to get a hardcopy. Word processors vary considerably, but all word processors support the following basic features: • insert text: Allows you to insert text anywhere in the document. • delete text: Allows you to erase characters, words, lines, or pages as easily as you can cross them out on paper. • cut and paste : Allows you to remove (cut) a section of text from one place in a document and insert ( p a s t e ) it somewhere else. • copy : Allows you to duplicate a section of text. • page size and margins : Allows you to define various page sizes and margins, and the word processor will automatically readjust the text so that it fits. • search and replace : Allows you to direct the word processor to search for a particular word or phrase. You can also direct the word processor to replace one group of characters with another everywhere that the first group appears. • word wrap : The word processor automatically moves to the next line when you have filled one line with text, and it will readjust text if you change the margins. • print: Allows you to send a document to a printer to get hardcopy. Word processors that support only these features (and maybe a few others) are called text editors. Most word processors, however, support additional features that enable you to manipulate and format documents in more sophisticated ways. These more advanced word processors are sometimes called full-featured word processors. Full-featured word processors usually support the following features: 54

• file management : Many word processors contain file management capabilities that allow you to create, delete, move,

and search for files. font specifications: Allows you to change fonts within a document. For example, you can specify bold, italics, and underlining. Most word processors also let you change the font size and even the typeface. • footnotes and cross-references: Automates the numbering and placement of footnotes and enables you to easily cross-reference other sections of the document. • graphics graphics: Allows you to embed illustrations and graphs into a document. Some word processors let you create the illustrations within the word processor; others let you insert an illustration produced by a different program. • headers , footers , and page numbering: Allows you to specify customized headers and footers that the word processor will put at the top and bottom of every page. The word processor automatically keeps track of page numbers so that the correct number appears on each page. • layout : Allows you to specify different margins within a single document and to specify various methods for indenting paragraphs. • macros : A macro is a character or word that represents a series of keystrokes. The keystrokes can represent text or commands. The ability to define macros allows you to save yourself a lot of time by replacing common combinations of keystrokes. • merges: Allows you to merge text from one file into another file. This is particularly useful for generating many files that have the same format but different data. Generating mailing labels is the classic example of using merges. • spell checker : A utility that allows you to check the spelling of words. It will highlight any words that it does not recognize. • tables of contents and indexes: Allows you to automatically create a table of contents and index based on special codes that you insert in the document. • thesaurus: A built-in thesaurus that allows you to search for synonyms without leaving the word processor. • windows : Allows you to edit two or more documents at the same time. Each document appears in a separate window. This is particularly valuable when working on a large project that consists of several different files. • WYSIWYG (what you see is what you get): With WYSIWYG, a document appears on the display screen exactly as it will look when printed.

The line dividing word processors from desktop publishing systems is constantly shifting. In general, though, desktop publishing applications support finer control over layout, and more support for full-color documents. Open:- This tools is used for displaying a dialogue box for opening existing files from the directory we specify. The shortcut command for open is Ctrl+O Save:- This tools is used for saving our current files that we are working with it or if we have not saved, i.e., our file if it is a new one, then it prompts us to save as -where we need to specify the directory and the file name . The shortcut key for save is Ctrl+S Print:- This tools is used for printing our document or the document which we choose to print .The shortcut key for print is Ctrl+P Undo:- This tools is used for canceling any commands that we have used recently . The shortcut key for undo is Ctrl+Z Redo: This tools is used for redoing whatever command or action we undo. The shortcut key for redo is Ctrl+Y Text justification: - when we click on this tools the text we type or selected will be justified, i.e., aligned on both sides. In other word it is the combination of left and right alignment. The text appear to be balanced between left and right Find and replace: - The tools Find is used for searching any text in the document, if such text is found we can replaced by another text which we want to using the tools Replace. The shortcut key for find is Ctrl+F. The shortcut key for Replace is Ctrl+H Document formatting Formatting a document is the way or process of changing the outlook of the document that means making the outlook of the document attractive as per our desire using different document formatting tools such as changing font styles, changing font sizes , changing alignment (right , left, centered, justified) making text bold, italic and putting underline for headings , putting background on the pages, putting header and footer notes, inserting bullet and numbering where necessary etc Speller and thesaurus Speller is a tool available in any word processing software by which we can check the spelling and grammar after each word or after finishing the whole document. It got the facility of using different English language and even now it has gone further including different international language, we can even include local words into its custom dictionary which can be used so easily whereas thesaurus is a tool which is used to see the word meanings, synonyms, antonyms etc of any words and even can change the meanings and can add our own meanings to it.

Templates/Style Sheets After designing a document, its format can be used again. Layout codes (margins, tabs, fonts, etc.) can be stored in a template file (style sheet) and applied to a new document.

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Mail Merge Creates customized letters from a form letter and a list of names and addresses. The list can be created as a document or can be imported from popular database formats.

Columns Columns can be created in all word processors by tabbing to a tab stop. However, true column capability wraps words to the next line within each column. Columns are required for writing resumes with employer information on the left and work history on the right. Script writing also requires column capability. Magazine-style columns flow words from the bottom of one column to the top of the next.

Graphics Vs. Text Based Graphics-based programs (Windows, Macintosh, etc.) show a close facsimile on screen of the typefaces that will be printed. Earlier text-based DOS programs always show the same type size on screen. Text-based word processors are fine for typing letters and documents with a simple format. They are also very responsive and good for creative writing. Some authors still use ancient DOS word processors because they are more flexible than many GUI-based products, and they run fine under Windows. Graphics-based systems are necessary for preparing newsletters and brochures that contain a variety of font styles and sizes.

The User Interface Word processing programs run from the ridiculous to the sublime. Some of the most awkward programs have sold well. As a novice, it is difficult to tell a good one from a bad one. It takes time to explore the nuances. Also, what is acceptable for the slow typist can be horrendous for the fast typist. Repetitive functions such as centering and changing display attributes (bold, italic, etc.) should be a snap. Changing margins, tabs, indents and fonts should also be easy. The most important component in word processing has nothing to do with software. The keyboard is the primary interface between the user and the machine, and the feel of the keys is critical. Key placement is also important. Document Collaboration

Document and file collaboration is a term used to describe tools or systems set up to help multiple people work together on a single document or file to achieve a single final version. Normally, this refers to software which allows teams to work on a single document, such as a Word document, at the same time from different computer terminals or mobile devices. Hence, document or file collaboration today is a system allowing people to collaborate across different locations using an Internet, or "cloud", enabled approach. Word Art WordArt is a text-styling feature that is available in the Microsoft Office suite of products. It allows users to create stylized text with various "special effects" such as textures, outlines, and many other manipulations that are not available through the standard font formatting. For example, one can create shadows, rotate, "bend" and "stretch" the shape of the text.

Spread Sheet A spreadsheet is a computer application with tools that increase the user's productivity in capturing, analyzing, and sharing tabular data sets. It displays multiple cells usually in a two-dimensional matrix or grid consisting of rows and columns (in other words, a table, hence "tabular"). Each cell contains alphanumeric text, numeric values, or formulas. A formula defines how the content of that cell is to be calculated from the contents of any other cell (or combination of cells) each time any cell is updated. A pseudo third dimension to the matrix is sometimes applied as another layer, or layers/sheets, of two-dimensional data. Spreadsheets developed as computerized simulations of paper accounting worksheets. They boost productivity because of their ability to re-calculate the entire sheet automatically after a change to a single cell is made (which was a manual process in the days of paper ledgers). Spreadsheets have now replaced paper-based systems throughout the business world, with any exceptions being rare, because of the much greater productivity that they make possible, and thus the competitive disadvantage of spreadsheet illiteracy. Although they were first developed for accounting or bookkeeping tasks, they now are used extensively in any context where tabular lists are built, sorted, and shared.

Spread Sheet Concepts The main concepts are those of a grid of cells, called sheet, with either raw data, called values, or formulas in the cells. Formulas say how to mechanically compute new values from existing values. Values are generally numbers, but can be also pure text, dates, months, etc. Extensions of these concepts include logical spreadsheets. Various tools for programming sheets, visualizing data, remotely connecting sheets, displaying cells dependencies, etc. are commonly provided. Cells A "cell" can be thought of as a box for holding a datum. A single cell is usually referenced by its column and row (A2 would represent the cell below containing the value 10). Usually rows, representing the dependant variables, are referenced in decimal notation 56

starting from 1, while columns representing the independent variables using the letters A-Z as numerals. Its physical size can usually be tailored for its content by dragging its height or width at box intersections (or for entire columns or rows by dragging the column or rows headers). Cell formatting Depending on the capability of the spreadsheet application, each cell (like its counterpart the "style" in a word processor) can be separately formatted using the attributes of either the content (point size, color, bold or italic) or the cell (border thickness, background shading, color). To aid the readability of a spreadsheet, cell formatting may be conditionally applied to data - for example, a negative number may be displayed in red. A cell's formatting does not typically affect its content and depending on how cells are referenced or copied to other worksheets or applications, the formatting may not be carried with the content. Cell reference In place of a named cell, an alternative approach is to use a cell (or grid) reference. Most cell references indicate another cell in the same spreadsheet, but a cell reference can also refer to a cell in a different sheet within the same spreadsheet, or (depending on the implementation) to a cell in another spreadsheet entirely, or to a value from a remote application. A typical cell reference in "A1" style consists of one or two case-insensitive letters to identify the column (if there are up to 256 columns: A-Z and AA-IV) followed by a row number (e.g. in the range 1-65536). Either part can be relative (it changes when the formula it is in is moved or copied), or absolute (indicated with $ in front of the part concerned of the cell reference). The alternative "R1C1" reference style consists of the letter R, the row number, the letter C, and the column number; relative row or column numbers are indicated by enclosing the number in square brackets. Most current spreadsheets use the A1 style, some providing the R1C1 style as a compatibility option. When the computer calculates a formula in one cell to update the displayed value of that cell, cell reference(s) in that cell, naming some other cell(s), cause the computer to fetch the value of the named cell(s). Cell ranges Likewise, instead of using a named range of cells, a range reference can be used. Reference to a range of cells is typically of the form (A1:A6) which specifies all the cells in the range A1 through to A6. A formula such as "=SUM(A1:A6)" would add all the cells specified and put the result in the cell containing the formula itself. Data format A cell or range can optionally be defined to specify how the value is displayed. The default display format is usually set by its initial content if not specifically previously set, so that for example "31/12/2007" or "31 Dec 2007" would default to the cell format of "date". Similarly adding a % sign after a numeric value would tag the cell as a percentage cell format. The cell contents are not changed by this format, only the displayed value. Some cell formats such as "numeric" or "currency" can also specify the number of decimal places. Sheets In the earliest spreadsheets, cells were a simple two-dimensional grid. Over time, the model has been expanded to include a third dimension, and in some cases a series of named grids, called sheets. The most advanced examples allow inversion and rotation operations which can slice and project the data set in various ways. Formulas A formula identifies the calculation needed to place the result in the cell it is contained within. A cell containing a formula therefore has two display components; the formula itself and the resulting value. The formula is normally only shown when the cell is selected by "clicking" the mouse over a particular cell; otherwise it contains the result of the calculation. A formula assigns values to a cell or range of cells, and typically has the format: =expression

Where the expression consists of: • values, such as 2, 9.14 or 6.67E-11; • references to other cells, such as, e.g., A1 for a single cell or B1: B3 for a range; • arithmetic operators, such as +, -, *, /, and others; • relational operators, such as >=, <, and others; and, • functions, such as SUM(), TAN(), and many others.

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Lecturer: Biran Limbu, Mahendra Multiple Campus, Dharan (BBA 1st Semester) -TU

Functions Spreadsheets usually contain a number of supplied functions, such as arithmetic operations (for example, summations, averages and so forth), trigonometric functions, statistical functions, and so forth. In addition there is often a provision for user-defined functions. Charts Many spreadsheet applications permit charts, graphs or histograms to be generated from specified groups of cells which are dynamically re-built as cell contents change. The generated graphic component can either be embedded within the current sheet or added as a separate object.

Presentation Presentation is the practice of showing and explaining the content of a topic to an audience or learner. Presentations come in nearly as many forms as there are life situations. In the business world, there are sales presentations, informational and motivational presentations, first encounters, interviews, briefings, status reports, image-building, and of course, the inevitable training sessions. Presentations can also be categorized as vocational and a vocational. In addition, they are expository or persuasive. And they can be impromptu, extemporaneous, written, or memorizes. When looking at presentations in the broadest terms, it's more important to focus on their purpose. There are three basic purposes for giving oral presentations: 1. To inform 2. To persuade (convince) 3. To build good will Presentation program A presentation program (also called a presentation graphics program) is a computer software package used to display information, normally in the form of a slide show. It typically includes three major functions: an editor that allows text to be inserted and formatted, a method for inserting and manipulating graphic images and a slide-show system to display the content. Microsoft PowerPoint Microsoft PowerPoint is a full-featured desktop presentation program. It is part of the Office suite and can be purchased separately. A presentation can be a collection of slides relating to a specific topic, which may be shown while the topic is discussed or may be shown as a continuous show. From the presentation slides, handouts, speaker notes, or outlines can also be prepared. PowerPoint contains graphic tools and many kinds of pictures and graphs to be imported. A Macintosh version is available which functions almost identically to the Windows version. Presentations created in either platform can be run from the other, without any conversion needed. Slide Slide is a page, document, or template where all the content of the presentation is written. In other word a single page in the slide show presentation is known as slide Presentation Collection of more than one slide together on a particular topic is known as presentation Presentation contain different slides, different contents, different objects and different animations Slide show Slide show is the way of presenting the slides to a mass of people in real sense. how the slides are flown from one to another is defined in the slide show. It displays all the slides in full screen .This are the real world happening of the presentation. All the graphics, text flows, picture, animation can only seen in this show or views but can't be added or modified Transactions In Microsoft PowerPoint, slide transitions are motion effects that occur in Slide Show view when you move from one slide to the next during a presentation. You can control the speed, add sound, and even customize the properties of transition effects. To add a transition first of all select a slide in the left hand panel that contains the Slides and Outline tabs (I'd keep it simple and work in the Slides tab). The transition will occur immediately before the selected slide is displayed. Click Transitions > Transition To This Slide, and then click on the transition you want to use. If you want to see a larger selection of transitions, click on the more button (the down arrow at the bottom right of the group. 59

Lecturer By: Biran Limbu, CODES Computer Consultant, Dharan, Nepal. Email:[email protected]

Features of PowerPoint presentation: Creating A New And Opening An Existing Presentation • Creating A New Presentation • Creating A New Presentation Based On A Template • Opening An Existing Presentation PowerPoint Basic Tasks • Adding New Slides • Deleting Slides • Moving Slides • PowerPoint Views • Modifying Backgrounds Templates • Applying PowerPoint Templates • Creating Your Own PowerPoint Template PowerPoint Text • Using Textboxes • Content Placeholders • Formatting Text Graphics • Insert Powerpoint Image • Using Clipart Images • PowerPoint Transitions • Creating Animations • Adding Sounds Miscellaneous PowerPoint Tasks • Powerpoint Spell Check • Running The Slideshow • Pointer Options • Saving Presentations • Saving As A Web Page • Printing Presentations

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Lecturer: Biran Limbu, Mahendra Multiple Campus, Dharan (BBA 1st Semester) -TU

UNIT XI Financial information system Financial Management Information Systems accumulate and analyze financial data in order to make good financial management decisions in running the business. The basic objective of the financial information system is to meet the firm's financial obligations as they come due, using the minimal amount of financial resources consistent with an established margin of safety. Outputs generated by the system include accounting reports, operating and capital budgets, working capital reports, cash flow forecast, and various Analysis reports. The evaluation of financial data may be performed through ratio analysis, trend evaluation, and financial planning modeling. Financial planning and forecasting are facilitated if used in conjunction with a Decision Support System (DSS). Financial Information System should: • Collect accurate, timely, complete, reliable, consistent information • Provide sufficient management reporting • Support government-wide and agency policy decisions • Support budget preparation and execution • Facilitate financial statement preparation • Provide information for central agency budgeting, analysis and government-wide reporting • Provide complete audit trail to facilitate audits. FIS Building Blocks An FMIS will consist of several elements with different functions. In the description that follows, the term “module” will imply that the system is a sub-element in a FMIS. The core of an FMIS could be expected to include the following modules and systems: • General ledger • Budgetary accounting • Accounts payable • Accounts receivable The noncore or other modules are, inter alia: • Payroll system • Budget development • Procurement • Project ledger • Asset module. Financial Information Software Financial software is a type of software that is specifically designed to automate, assist and store financial information of a personal or business nature. It handles the storage, analysis, management and processing of a set of financial transactions, records and processes. Financial software is built on the principles of financial information management. It may be executed as standalone software or as part of a financial information system (IS). Most financial software incorporates all facets of personal or business finance and provides numerous features, including: 61

Lecturer By: Biran Limbu, CODES Computer Consultant, Dharan, Nepal. Email:[email protected]

• • • • •

Basic financial data management Financial transactions and management Budgeting Account management Financial assets management

Financial software may be classified as business financial software or personal financial software. Moreover, financial software also may provide other related services, such as accounting and/or bookkeeping, and be integrated within other enterprise information systems. Components of Financial information systems An information system is essentially made up of five components: 1. People 2. Data 3. Procedures 4. Hardware 5. Software People The computer based information system is developed by the people and for the people. Computer users are people who will use the computer system. The developers are the people, who will develop the system on basis of requirement. Data Data is a collection of raw facts and figures. There are several ways the organize data e.g. DataBase Management System, File Management System. A computer based information system is used to process data into information. Procedures Procedures are the actions that are used by the people to process the data into information. Operating procedures are used to operate the computer, Data entry, Maintenance, Back up and error recovery. Emergency procedures are used to trouble shoot. Hardware Different types of Hardware used for Computer Based Information System. Input hardware (Keyboard, mouse, etc.), Processing hardware (Processor, Memory, etc), Output hardware (Monitor, printer, etc) and Storage hardware etc. Software Different types of software used in CBIS. Application software includes Word processing, electronic spreadsheets, graphical packages and databases. System software includes operation systems and communication software. Features of Financial information system An effective financial management system improves short- and long-term business performance by streamlining invoicing and bill collection, eliminating accounting errors, minimizing record-keeping redundancy, ensuring compliance with tax and accounting regulations, helping personnel to quantify budget planning, and offering flexibility and expandability to accommodate change and growth. Features of a good financial management system include: • Keeping all payments and receivables transparent. • Amortizing prepaid expenses. 62

Lecturer: Biran Limbu, Mahendra Multiple Campus, Dharan (BBA 1st Semester) -TU

• • • • • • • •

Depreciating assets according to accepted schedules. Keeping track of liabilities. Coordinating income statements, expense statements, and balance sheets. Balancing multiple bank accounts. Ensuring data integrity and security. Keeping all records up to date. Maintaining a complete and accurate audit trail. Minimizing overall paperwork.

Classification of Information System In any given organization information system can be classified based on the usage of the information. Therefore, an information system in an organization can be divided into operations support system and management support system. Operations support system In an organization, data input is done by the end user which is processed to generate information products i.e. reports, which are utilized by internal and or external users. Such a system is called operation support system. The purpose of the operation support system is to facilitate business transaction, control production, support internal as well as external communication and update organization central database. The operation support system is further divided into a transaction-processing system, processing control system and enterprise collaboration system. Transaction Processing System (TPS) In manufacturing organization, there are several types of transaction across department. Typical organizational departments are Sales, Account, Finance, Plant, Engineering, Human Resource and Marketing. Across which following transaction may occur sales order, sales return, cash receipts, credit sales; credit slips, material accounting, inventory management, depreciation accounting, etc. These transactions can be categorized into batch transaction processing, single transaction processing and real time transaction processing. Process Control System In a manufacturing organization, certain decisions are made by a computer system without any manual intervention. In this type of system, critical information is fed to the system on a real-time basis thereby enabling process control. This kind of systems is referred as process control systems. Enterprise Collaboration System In recent times, there is more stress on team effort or collaboration across different functional teams. A system which enables collaborative effort by improving communication and sharing of data is referred to as an enterprise collaboration system. Management Support System Managers require precise information in a specific format to undertake an organizational decision. A system which facilitates an efficient decision making process for managers is called management support system. Management support systems are essentially categorized as management information system, decision support system, expert system and accounting information system.

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Lecturer By: Biran Limbu, CODES Computer Consultant, Dharan, Nepal. Email:[email protected]

UNIT XII Marketing Information System A marketing information system (MIS) is a management information system designed to support marketing decision making. It brings together many different kinds of data, people, equipment and procedures to help an organization make better decisions . American academic Philip Kotler has defined it more broadly as "people, equipment, and procedures to gather, sort, analyze, evaluate, and distribute needed, timely, and accurate information to marketing decision makers. " Not to be confused for a management information system, marketing information systems are designed specifically for managing the marketing aspects of the business. MIS not only indicates how things are going, but also why and where performance is failing to meet the plan. These reports include near real-time performance of cost centers and projects with detail sufficient for individual accountability. MISs produce fixed, regularly scheduled reports to middle and operational level managers to identify and inform structured and semi-structured decision problems. Some of these benefits include: • It enables managers to share information and work together virtually. • It helps marketers collaborate with customers on product designs and customer requirements. • It addresses operational needs through customer management systems that focus on the day-to-day processing of customer transactions from the initial sale through customer service. • The availability of the customer data and feedback can help the company align their business processes according to the needs of the customers. The effective management of customer data can help the company perform direct marketing and promotional activities. • Information is considered to be an important asset for any company in the modern competitive world. The consumer buying trends and behaviors can be predicted by the analysis of sales and revenue reports from each operating region of the company. Decision Making Decision making is often seen as the center of what managers do, something that engages most of a managers time. It is one of the areas that information systems have sought most of all to affect (with mixed success). Decision making can be divided into 3 types: strategic, management control and operations control. Strategic decision making: This level of decision making is concerned with deciding on the objectives, resources and policies of the organization. A major problem at this level of decision making is predicting the future of the organization and its environment, and matching the characteristics of the organization to the environment. This process generally involves a small group of high-level managers who deal with very complex, non-routine problems. For example, some years ago, a medium-sized food manufacturer in an East African country faced strategic decisions concerning its range of pasta products. These products constituted a sizeable proportion of the company's sales turnover. However, the company was suffering recurrent problems with the poor quality of durum wheat it was able to obtain resulting in a finished product that was too brittle. Moreover, unit costs were shooting up due to increasingly frequent breakdowns in the ageing equipment used in pasta production. The company faced the decision whether to make a very large investment in new machinery or to accept the offer of another 64

Lecturer: Biran Limbu, Mahendra Multiple Campus, Dharan (BBA 1st Semester) -TU

manufacturer of pasta products, in a neighboring country, that it should supply the various pasta products and the local company put its own brand name on the packs. The decision is strategic since the decision has implications for the resource base of the enterprise, i.e. its capital equipment, its work force, its technological base etc. The implications of strategic decisions extend over many years, often as much as ten to fifteen years. Management control decisions: Such decisions are concerned with how efficiently and effectively resources are utilized and how well operational units are performing. Management control involves close interaction with those who are carrying out the tasks of the organization; it takes place within the context of broad policies and objectives set out by strategic planners. An example might be where a transporter of agricultural products observes that his/her profits are declining due to a decline in the capacity utilization of his/her two trucks. The manager (in this case the owner) has to decide between several alternative courses of action, including: selling of trucks, increasing promotional activity in an attempt to sell the spare carrying capacity, increasing unit carrying charges to cover the deficit, or seeking to switch to carrying products or produce with a higher unit value where the returns to transport costs may be correspondingly higher. Management control decisions are more tactical than strategic. Operational control decisions: These involve making decisions about carrying out the " specific tasks set forth by strategic planners and management. Determining which units or individuals in the organization will carry out the task, establishing criteria of completion and resource utilization, evaluating outputs - all of these tasks involve decisions about operational control. The focus here is on how the enterprises should respond to day-to-day changes in the business environment. In particular, this type of decision making focuses on adaptation of the marketing mix, e.g. how should the firm respond to an increase in the size of a competitor's sales force? should the product line be extended? should distributors who sell below a given sales volume be serviced through wholesalers rather than directly, and so on. Within each of these levels, decision making can be classified as either structured or unstructured. Unstructured decisions are those in which the decision maker must provide insights into the problem definition. They are novel, important, and non-routine, and there is no well-understood procedure for making them. In contrast, structured decisions are repetitive, routine, and involve a definite procedure for handling them so that they do not have to be treated each time as if they were new. Structured and unstructured problem solving occurs at all levels of management. In the past, most of the success in most information systems came in dealing with structured, operational, and management control decisions. However, in more recent times, exciting applications are occurring in the management and strategic planning areas, where problems are either semi-structured or are totally unstructured. The literature has described 4 stages in decision making: • Intelligence • Design • choice • implementation That is, problems have to be perceived and understood; once perceived solutions must be designed; once solutions are designed, choices have to be made about a particular solution; finally, the solution has to be implemented. 65

Lecturer By: Biran Limbu, CODES Computer Consultant, Dharan, Nepal. Email:[email protected]

Intelligence involves identifying the problems in the organization: why and where they occur with what effects. This broad set of information gathering activities is required to inform managers how well the organization is performing and where problems exist. Management information systems that deliver a wide variety of detailed information can be useful, especially if they are designed to report exceptions. For instance, consider a commercial organization marketing a large number of different products and product variations. Management will want to know, at frequent intervals, whether sales targets are being achieved. Ideally, the information system will report only those products/product variations which are performing substantially above or below target. Designing many possible solutions to the problems is the second phase of decision making. This phase may require more intelligence to decide if a particular solution is appropriate. Here, more carefully specified and directed information activities and capabilities focused on specific designs are required. Choosing among alternative solutions is the third step in the decision making process. Here a manager needs an information system which can estimate the costs, opportunities and consequences of each alternative problem solution. The information system required at this stage is likely to be fairly complex, possibly also fairly large, because of the detailed analytic models required to calculate the outcomes of the various alternatives. Of course, human beings are used to making such calculations for themselves, but without the aid of a formal information system, we rely upon generalization and/or intuition. Implementing is the final stage in the decision making process. Here, managers can install a reporting system that delivers routine reports on the progress of a specific solution, some of the difficulties that arise, resource constraints, and possible remedial actions.

Components of a marketing information system

A marketing information system (MIS) is intended to bring together disparate items of data into a coherent body of information. An MIS is, as will shortly be seen, more than raw data or information suitable for the purposes of decision making. An MIS also provides methods for interpreting the information the MIS provides. "A marketing information system is a continuing and interacting structure of people, equipment and procedures to gather, sort, analyze, evaluate, and distribute pertinent, timely and accurate information for use by marketing decision makers to improve their marketing planning, implementation, and control". The explanation of this model of an MIS begins with a description of each of its four main constituent parts: • the internal reporting systems 66

Lecturer: Biran Limbu, Mahendra Multiple Campus, Dharan (BBA 1st Semester) -TU

• marketing research system • marketing intelligence system • marketing models. It is suggested that whilst the MIS varies in its degree of sophistication - with many in the industrialized countries being computerized and few in the developing countries being so - a fully-fledged MIS should have these components, the methods (and technologies) of collection, storing, retrieving and processing data notwithstanding. Internal reporting systems: All enterprises which have been in operation for any period of time nave a wealth of information. However, this information often remains under-utilized because it is compartmentalized, either in the form of an individual entrepreneur or in the functional departments of larger businesses. That is, information is usually categorized according to its nature so that there are, for example, financial, production, manpower, marketing, stockholding and logistical data. Often the entrepreneur, or various personnel working in the functional departments holding these pieces of data, do not see how it could help decision makers in other functional areas. Similarly, decision makers can fail to appreciate how information from other functional areas might help them and therefore do not request it. The internal records that are of immediate value to marketing decisions are: orders received, stockholdings and sales invoices. These are but a few of the internal records that can be used by marketing managers, but even this small set of records is capable of generating a great deal of information. Below, is a list of some of the information that can be derived from sales invoices. · Product type, size and pack type by territory · Product type, size and pack type by type of account · Product type, size and pack type by industry · Product type, size and pack type by customer · Average value and/or volume of sale by territory · Average value and/or volume of sale by type of account · Average value and/or volume of sale by industry · Average value and/or volume of sale by sales person By comparing orders received with invoices an enterprise can establish the extent to which it is providing an acceptable level of customer service. In the same way, comparing stockholding records with orders received helps an enterprise ascertain whether its stocks are in line with current demand patterns. Marketing research systems: The general topic of marketing research has been the prime ' subject of the textbook and only a little more needs to be added here. Marketing research is a proactive search for information. That is, the enterprise which commissions these studies does so to solve a perceived marketing problem. In many cases, data is collected in a purposeful way to address a well-defined problem (or a problem which can be defined and solved within the course of the study). The other form of marketing research centres not around a specific marketing problem but is an attempt to continuously monitor the marketing environment. These monitoring or tracking exercises are continuous marketing research studies, often involving panels of farmers, consumers or distributors from which the same data is collected at regular intervals. Whilst the ad hoc study and continuous marketing research differs in the orientation, yet they are both proactive.

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Lecturer By: Biran Limbu, CODES Computer Consultant, Dharan, Nepal. Email:[email protected]

Marketing intelligence systems: Whereas marketing research is focused, market intelligence is not. A marketing intelligence system is a set of procedures and data sources used by marketing managers to sift information from the environment that they can use in their decision making. This scanning of the economic and business environment can be undertaken in a variety of ways, including

Unfocused scanning The manager, by virtue of what he/she reads, hears and watches exposes him/herself to information that may prove useful. Whilst the behavior is unfocused and the manager has no specific purpose in mind, it is not unintentional Semi-focused Again, the manager is not in search of particular pieces of information that he/she is actively scanning searching but does narrow the range of media that is scanned. For instance, the manager may focus more on economic and business publications, broadcasts etc. and pay less attention to political, scientific or technological media. Informal search This describes the situation where a fairly limited and unstructured attempt is made to obtain information for a specific purpose. For example, the marketing manager of a firm considering entering the business of importing frozen fish from a neighboring country may make informal inquiries as to prices and demand levels of frozen and fresh fish. There would be little structure to this search with the manager making inquiries with traders he/she happens to encounter as well as with other ad hoc contacts in ministries, international aid agencies, with trade associations, importers/exporters etc. Formal search This is a purposeful search after information in some systematic way. The information will be required to address a specific issue. Whilst this sort of activity may seem to share the characteristics of marketing research it is carried out by the manager him/herself rather than a professional researcher. Moreover, the scope of the search is likely to be narrow in scope and far less intensive than marketing research Marketing intelligence is the province of entrepreneurs and senior managers within an agribusiness. It involves them in scanning newspaper trade magazines, business journals and reports, economic forecasts and other media. In addition it involves management in talking to producers, suppliers and customers, as well as to competitors. Nonetheless, it is a largely informal process of observing and conversing. Some enterprises will approach marketing intelligence gathering in a more deliberate fashion and will train its sales force, after-sales personnel and district/area managers to take knowledge of competitors' actions, customer complaints and requests and distributor problems. Enterprises with vision will also encourage intermediaries, such as collectors, retailers, traders and other middlemen to be proactive in conveying market intelligence back to them. Marketing models: Within the MIS there has to be the means of interpreting information in order to give direction to decision. These models may be computerized or may not. Typical tools are: · Time series sales modes · Brand switching models · Linear programming · Elasticity models (price, incomes, demand, supply, etc.) · Regression and correlation models

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Lecturer: Biran Limbu, Mahendra Multiple Campus, Dharan (BBA 1st Semester) -TU

· Analysis of Variance (ANOVA) models · Sensitivity analysis · Discounted cash flow · Spreadsheet 'what if models These and similar mathematical, statistical, econometric and financial models are the analytical subsystem of the MIS. A relatively modest investment in a desktop computer is enough to allow an enterprise to automate the analysis of its data. Some of the models used are stochastic, i.e. those containing a probabilistic element whereas others are deterministic models where chance plays no part. Brand switching models are stochastic since these express brand choices in probabilities whereas linear programming is deterministic in that the relationships between variables are expressed in exact mathematical terms. Features of Marketing Information System

Continuous system : MIS is a permanent and continuous system of collecting information. It collects information continuously. Basic objective : The basic objective of MIS is to provide the right-information at the right-time to the right-people to help them take right decisions. Computer based system : MIS is a computer-based system. It uses computers for storing, analyzing and supplying information. It also uses micro-films for storing information. Therefore, it is very quick and accurate. Future-oriented : MIS is future-oriented. It provides information for solving future problems. It is not past-oriented. Used by all levels : MIS is used by all three levels of management, i.e. top, middle and lower. It is used for making 69

Lecturer By: Biran Limbu, CODES Computer Consultant, Dharan, Nepal. Email:[email protected]

marketing plans, policies and strategies. This is used to solve marketing problems and to take advantage of business opportunities. Sources : MIS collects information from both, internal and external sources. For example, information is collected from company records, publications, etc. Collects marketing information : MIS collects all types of marketing information. It collects information about the consumer competition, marketing environment, government policies, etc. It supplies this information to the marketing managers. Helps in decision making : MIS supplies up-to-date and accurate information. It helps marketing managers to take quick and right decisions. Complex process: Designing and operating a MIS is a complex process, especially with the firms involved in global trade. It requires convincing each unit of the firm about the value of timely and accurate information. Structured reports and control over the information make the process more complicated. Thus, computer specialists are used. Economical: Creating large database is easy with a computer. However, MIS is concerned with needed and timely information. Hence, only relevant data is stored. This reduces cost and efforts in data collection. Variety: MIS uses data from a variety of sources both within and outside the organization. Thus, it helps the marketing managers in exploratory research. It uncovers useful relationships and devel•opments. Ordinarily, such meaningful relationships would have been overlooked by the managers. Flexible: The system should be flexible. New changes should be incorporated easily, quickly and smoothly. Information technology is changing rapidly. When such new techniques are used, accuracy and utility of information improve. Role of Decision Making A decision support system (DSS) is an integrated set of computer tools allowing a decision maker to interact directly with computer to retrieve information useful in making semi structured and unstructured decisions. A decision support system (DSS) is an interactive computer system that is easily accessible to, and operated by non-computer specialists to assist them in planning and decision-making functions. While DSSs may differ in their emphases on data-access and modeling functions, there is an overriding emphasis in all such systems on user accessibility to data for decision-making. This decision-making applicability permits managers to simulate problems using formal mathematical models and to test the outcomes of various alternatives for reaching the best possible decision. The term decision support system refers to a class of systems, which support the process of making decision DSS allow the decision maker to retrieve data and test alternative solutions during the process of problem solving. The meaning of DSS is based on following assumptions about the role of the computer in effective decision-making. The DSS can provide analytical models for forecasting, simulation, and optimization. DSS tools include simple spreadsheets such as Excel, statistical analysis packages such as SPSS and SAS, on-line analytical processing (OLAP) tools, data mining applications, and neural networks. The DSS provides the user with the ability to explore multiple options. Typical DSS functions include models and tools for: 1. Sensitivity analysis. Decision-makers can explore changes in a strategic variable such as price and model its impact on demand or competitive behavior. 70

Lecturer: Biran Limbu, Mahendra Multiple Campus, Dharan (BBA 1st Semester) -TU

2. What-if analysis. Can be easily accomplished with a spreadsheet. Revenues and costs can be manipulated to show the impact of each variable on profits and cash flows. 3. Goal setting. Analysis focuses on the desired result and builds the resource base necessary to accomplish the goal. 4. Exception reporting. Analysis looks for results that exceed or fall short of stated goals or benchmarks. Which products or segments exceeded sales forecasts? Sometimes called gap analysis. 5. Pareto analysis. Analysis looks for activities that generate disproportionate results. For instance, the top 20 percent of customers may account for 80 percent of sales revenues. 6. Forecasting models. Econometric models are used to analyze time series data for the purpose of predicting future sales and market share levels. 7. Simulation models. Monte Carlo simulations address marketing decision making under conditions of uncertainty. Variables such as the market price, unit variable cost, and quantity sold are not known ahead of the product investment decision. Simulation models allow the marketer to analyze risk and assess the probabilities of likely outcomes of their decisions. 8. Scorecards and dashboards. Scorecard systems can present a consistent framework for tracking the effectiveness of marketing activities. Decision-Making Decision-making is a conscious human process. A particular course of action from among a set of possible alternatives. To decide means to come to a conclusion or resolution, decision-making defined as the “conscious and human process, involving both individual and social phenomenon based upon factual and value premises, which concludes with a choice of one behavioral activity from among one or more alternatives with the intention of moving toward some desired state of affairs”. It represents a course of behavior or action about what must or must not be done. decision-making is the selecting of action from among alternatives to achieve a specific objective or solve specific problem (Donald, 1963). The art of decision-making provide us a variety of approaches, methods and techniques helpful and useful for making high quality of decision. A decision maker, as an individual, or as a member of formal organization with his own philosophy and perception of the organization, selects for optimizing values within the constraints imposed by the organization.

*Thank You*

Lecturer: Biran Limbu (TU, BBA 1st Semester) Mahendra Multiple Campus, Dharan Nepal

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