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introduction to information technology e-528-529 sector-7 dwarka new delhi-110075 nr ramphal chowk and sector 9 metro station ph 011-47350606 m 7838010301-04 www.eduproz.in educate anytime anywhere greetings for the day about eduproz we at eduproz started our voyage with a dream of making higher education available for everyone since its inception eduproz has been working as a stepping-stone for the students coming from varied backgrounds the best part is ­ the classroom for distance learning or correspondence courses for both management mba and bba and information technology mca and bca streams are free of cost experienced faculty-members a state-of-the-art infrastructure and a congenial environment for learning are the few things that we offer to our students our panel of industrial experts coming from various industrial domains lead students not only to secure good marks in examination but also to get an edge over others in their professional lives our study materials are sufficient to keep students abreast of the present nuances of the industry in addition we give importance to regular tests and sessions to evaluate our students progress students can attend regular classes of distance learning mba bba mca and bca courses at eduproz without paying anything extra our centrally air-conditioned classrooms well-maintained library and wellequipped laboratory facilities provide a comfortable environment for learning honing specific skills is inevitable to get success in an interview keeping this in mind eduproz has a career counselling and career development cell where we help student to prepare for interviews our dedicated placement cell has been helping students to land in their dream jobs on completion of the course eduproz is strategically located in dwarka west delhi walking distance from dwarka sector 9 metro station and 4-minutes drive from the national highway students can easily come to our centre from anywhere delhi and neighbouring gurgaon haryana and avail of a quality-oriented education facility at apparently no extra cost why choose edu proz for distance learning · · · · · · edu proz provides class room facilities free of cost in eduproz class room teaching is conducted through experienced faculty class rooms are spacious fully air-conditioned ensuring comfortable ambience course free is not wearily expensive placement assistance and student counseling facilities edu proz unlike several other distance learning courses strives to help and motivate pupils to get eduproz page 1

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introduction to information technology high grades thus ensuring that they are well placed in life students are groomed and prepared to face interview boards mock tests unit tests and examinations are held to evaluate progress special care is taken in the personality development department · · · have a good day eduproz page 2

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introduction to information technology karnataka state open university ksou was established on 1st june 1996 with the assent of h.e governor of karnataka as a full fledged university in the academic year 1996 vide government notification no/edi/uov/dated 12th february 1996 karnataka state open university act ­ 1992 the act was promulgated with the object to incorporate an open university at the state level for the introduction and promotion of open university and distance education systems in the education pattern of the state and the country for the co-ordination and determination of standard of such systems keeping in view the educational needs of our country in general and state in particular the policies and programmes have been geared to cater to the needy karnataka state open university is a ugc recognised university of distance education council dec new delhi regular member of the association of indian universities aiu delhi permanent member of association of commonwealth universities acu london uk asian association of open universities aaou beijing china and also has association with commonwealth of learning col karnataka state open university is situated at the north­western end of the manasagangotri campus mysore the campus which is about 5 kms from the city centre has a serene atmosphere ideally suited for academic pursuits the university houses at present the administrative office academic block lecture halls a well-equipped library guest house cottages a moderate canteen girls hostel and a few cottages providing limited accommodation to students coming to mysore for attending the contact programmes or term-end examinations eduproz page 3

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introduction to information technology unit1 computer fundamentals · this unit deals with generations of computers this unit also includes classification of computers according to their size and capabilities the different input-output devices used with the computers it deals with central processing unit memory unit terms hardware software computer languages the advantages and disadvantages of computers are also discussed in this unit today computers have become part of our life usage of computers in different fields has become a necessity in the present competitive world lot of work and evolutions has transpired from the initial computer systems to the present day computer systems computers are made up of electrical electronic and mechanical components computers are just the machines and you must specify the work that is to be carried out by the computer thus to carry out a specific task series of instructions must be given to the computer in a particular order objectives to understand · generations of computers · classification of computers · organization of computers · input-output devices · central processing unit · memory unit primary and secondary memory · the terms hardware and software · computer languages · application of computers · advantages and disadvantages of computers history eduproz page 4

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introduction to information technology the tool known as abacus was the age-old tool used by man to count and calculate was designed and developed by chinese some 5000 years ago blaise pascal designed a working mechanical calculator in 1642 these devices were able to add and subtract directly whereas multiplication and division were performed through repeated addition and subtraction respectively gottfried von leibnitz a german modified pascal s calculating machine which could multiply numbers directly in 1833 charles babbage an english scientist designed analytical engine using tooth wheels so that it could perform all mathematical operations in a predetermined sequence using a set of operational instructions so he is called as father of modern computers lady ada lovelace is considered as the first lady computer programmer as she has developed the concept of writing systematic operational instructions for the analytical engine in 1850 george boole an english mathematician proposed logic theory of using the binary two number system this number system had only two numbers 0 and 1 in this procedures all the quantities are represented in terms of o and 1 for example 9 is represented as 00001001 bool proposed a logic popularly known as boolean algebra computer processors are designed on this system of logic a statistician dr herman hollerith developed a punched card that would contain data coded in form of punched holes self assessment questions 1 who is the first lady computer programmer 2 what is logic proposed by an english mathematician george bool generations of computers evolution of modern computer is commonly considered in terms of generation of computers first generation 1940-1956 vacuum tubes the computers of this generation were made of vacuum tubes for circuitry and magnetic drums for memory this made computers bulky and heavy punched cards were used to feed the information magnetic tapes were used as external storage devices they were very expensive to operate and in addition to using a great deal of electricity generated a eduproz page 5

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introduction to information technology lot of heat and occupied a large amount of space these machines used machine and assembly level language the univac and eniac computers are examples of first-generation computing devices second generation 1956-1963 transistors the computers of this generation made up of transistors replacing vacuum tubes these are small in size so the machines occupied a less amount of space the use transistors made the computers work much faster 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 the development of higher-level languages like fortran cobol and basic was possible third generation 1965-1971 integrated circuits the computers of these generations were made up of ic integrated circuits integrated circuits mean incorporation of hundred of transistors on a single silicon chip these were still smaller than the computers of second-generation machines heat generated was also less and occupied less space 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 microprocessors the computers of this generation saw the advent of large scale integration lsi and very large scale integration vlsi which incorporated several thousands transistors in a single chip the main characteristic of this generation computers is the evolution of the use of microprocessors microprocessors had thousands of integrated circuits were built onto a single silicon chip 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 self assessment questions 1 what are the components used in second and third generation computers eduproz page 6

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introduction to information technology 2 give example for first generation computers classification of computers computers are classified according to their sizes and their capabilities broadly they may be categorized as personal computers lap top computers minicomputers mainframes and supercomputers personal computers a microcomputer is the smallest general purpose processing system functionally it is similar to any other large system microcomputers are selfcontained units and usually designed for use by one person at a time minicomputers a minicomputer is medium sized computer that is more powerful than a microcomputer an important distinction between a microcomputer and a minicomputer is that a minicomputer is usually to serve multiple users simultaneously mainframes computers computers with large storage capacities and very high speed of processing are known as mainframes they support a large number of terminals for simultaneous use by a number of users super computers these have extremely large storage area and computing speeds which are many times faster than earlier discussed machines while the speed of earlier discussed computers measured in turns of million instructions per second whereas in supercomputers speed is measured as tens of millions of operations per second an operation is made of many instruction these have more than one processor in it and the processing is carried out in parallel the super computers are used in applications include large scale numerical problems in scientific and engineering disciplines like weather forecasting atomic research space research etc lap top note book computers these are the computers which are small in size and weigh few kgs these computers can be carried from one place to another easily the people who are always on the move mostly use these this has all the capabilities of a personal computer it has an lcd screen and has rechargeable batteries eduproz page 7

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introduction to information technology now you can even get computers which can be placed on you palm hence the name palm top computers self assessment questions 1 classify the computers according to their size and capabilities organization of a computer a computer is a fast and accurate device which can accept data store data process them and give desired results as output the computer is organized into four units as shown in the following diagram 1.4.1 input unit any device designed to assist in the entry of data into a computer is known as input device input devices convert data from any convenient external format into binary codes that a computer can store and manipulate internally some of the most common most popularly used devices are discussed below mouse this input device is categorized as an pointing device because it is used to point and select an option on the monitor it is small boxlike object that is connected to the computer by a cable and can be rolled around on the table a pointer on eduproz page 8

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introduction to information technology the screen follows the movements of the mouse rolling the mouse left moves the pointer left by an equipment amount rolling the mouse in the right direction moves the pointer in the right direction rolling the mouse in the up direction moves the pointer in the up direction rolling the mouse in the down direction moves the pointer in the down direction and you can roll the mouse in a angular direction also in order to select an option on the computer screen the user should move the pointer at the desired position and press the button on the mouse the mouse can be used to open menus select texts for editing move objects on the screen draw images or diagrams etc a mouse can be classified on the basis of the number of buttons it has the technology it uses and the kind of interface it shares with the computer a mouse may have one two or three buttons the program that uses the mouse determines the function of each button a mouse may be classified as a mechanical mouse and an optical mouse on the basis of the technology it uses in a mechanical mouse the rubber-coated ball that projects through the bottom surface rotates as the mouse is moved along a flat surface and sends electrical signals to the system unit by means of switches inside the mouse this causes the cursor or pointer to move in a corresponding fashion an optical mouse uses diodes to emit light beam instead of a rotating ball to detect movement across a specially patterned metal pad light pen this is also categorized into a pointing device which can be used only with video displays it can be used to select an option by simply pointing at it or drawing figures directly on the screen an electron beam that repeatedly scans the display screen from left to right and from top to bottom produce a video display because of this scanning action each point on the display is illuminated at a slightly different time the light pen which is a pen like device has a photo detector at its tip the detector can detect changes in the brightness of the screen the light pen is connected to the computer by a cable when the pen is pointed at a particular spot on the screen the point is scanned and the photo detector records changes in the brightness and sends electrical pulses to the computer the computer can find out the exact spot with this information light pens are useful for menu-based applications it is also useful for drawing graphics in computer aided design software touch screen touch screens are normally used when information has to be accessed with minimum effort the user need to only touch the appropriate point on the display to point out an item to the computer this is again a kind of pointing devices joy stick eduproz page 9

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introduction to information technology this is another kind of input device used to play computer games which is connected to game port keyboard keyboards are the most widely used input devices the most popular keyboards are those that look feel and possibly sound like an ordinary typewriter keyboard alternatives are membrane keyboards whose keys are merely printed on a plastic membrane a pressure sensitive two-dimensional keyboard covered with a dust proofed and dirt proofed plastic sheet are useful in dirty environments keyboards are of different varieties generally a keyboard has 105 keys it features 12 function keys arranged at the top of the keyboard and larger backspace key a numeric keypad a cursor movement keypad toggle lights shift keys alt keys ctrl keys caps lock key num lock key spacebar key enter key alphabetical keys etc scanners these are the eyes of your computer they can see images or printed text and translate them into binary code most scanners collect data from a page by recording which areas are light and which areas are dark they contain a camera which is made up of thousands of tiny cells called charge coupled devices ccd each ccd detects whether a small part of the image is either light or dark it transmits this data to the cpu which then creates the image some scanners are sensitive enough to tell the difference between colors many scanners available nowadays are capable of not only scanning texts and graphics but also integrated text and graphic files scanners are used to reproduce photographs on the computer screen businesses use scanners fro storing documents on the computer optical character readers ocr these are another kind of input devices that are used to read any printed text they can interpret hand made marks handwritten characters machine printed characters and special symbols and codes optical character readers scan text character-by-character converts them into machine-readable codes and store it in the memory since they read characters at the rate of around 2600 characters per second this reduces the organizations the data inputting time eduproz page 10

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introduction to information technology magnetic ink character reader micr this is a device that identifies a character that is written with the ink that contains particles of magnetic material this device is mainly used to read the bank cheque mark sense reader this device is used to recognize the marks made by a pencil or pen on a specially designed paper these devices are also known as optical mark readers omr these devices are used in competitive exams to carry out the survey work etc bar code reader this is used to read different kind of vertical lines known as bars which signify some information 1.4.2 output unit any peripheral device that converts the stored binary coded data into convenient external forms as text and pictures are known as output devices some of the most popularly used output devices are discussed below visual display unit the visual display unit is an output device that gives visual representation of data they are also known as monitors they are television screen like devices used for displaying the output of computers computer monitors are often called cathode ray tubes crt computer users may select from monochrome black and white or color/graphics monitors crt monitors are too bulky for portable computers instead they have flat screen monitors many of these use liquid crystal display lcd screens an lcd screen is filled with molecules tiny particles of a liquid which reflects the light when the computer scans the screen some molecules twist to shut out light the off molecules cause a pixel to go dark and so form part of image lcds are similar to the display those found in calculators and digital watches are widely used in laptop computers and pocket computers printer the printer is another output device used to store the output for later reference using printers output can be obtained on paper the printers can be divided into two categories eduproz page 11

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introduction to information technology 1 impact printers 2 non impact printers impact printers these printers print by striking the type against the ribbon and the printer the example for this kind of printers is dot matrix printers daisy wheel printers and line printers they can produce carbon copies if necessary dot matrix printer the print head comprises a matrix of tiny needles usually of seven rows and five columns they are electrically driven and punch characters in the form of patterns of tiny dots the pattern of dots for each character is dictated by the information held electronically in the printer daisy wheel printer it is a character printer and derives it s name from the shape of the print wheel the daisy shape wheel is made of metal or plastic and holds the characters on its petal the wheel rotates at a high speed and when the required character is positioned over the ribbon a tinny hammer strikes it against the ribbon thus transferring the character symbol to the paper dot matrix and daisy wheel printers are called as character printers as they can print only one character at a time line printers it prints an entire line at a time and is the fastest printer it is the fastest printer as it prints all the characters in the line simultaneously non-impact printers these create the images without striking the type against the ribbon and paper instead they are practically noiseless and create images only on one copy the example for these kind of printers is ink-jet printers laser printers and thermal printers eduproz page 12

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introduction to information technology ink-jet printers these printers print characters by spraying electrically charged ink onto the paper they are capable of producing characters of various shapes and sizes we can take colored output laser printer these are high speed high quality printers a laser beam is used to burn characters images on the rotating drum and the heated surface area picks up the toner particles which is sprinkled on the paper thermal printer these kind of printers use heated dot matrix wires to print the output on a specially treated paper the output on a thermal paper fades quickly when exposed to light plotters this is an output device used to create high quality visuals on papers which cannot be obtained using a printer it is used to create presentation visuals charts graphs table and engineering plans a plotter consists of an arm that moves across the paper on which the diagram or graph needs to be drawn a pen moves along the arm and the arm itself moves relative to the paper a combination of the two thus provides movement along the horizontal and vertical axes to draw clear high quality designs a plotter needs high quality pens with special inks of different colors a plotter is more software dependent than any other peripheral and needs much more instructions that the printer for producing output 1.4.3 central processing unit the central processing unit cpu is the heart of the computer combined with the processing system of a computer the cpu carries out actions with help of arithmeticlogic unit alu this is done following a detailed set of instructions written in the main memory it also uses the main memory for temporary storage of information through the channels of information bus the cpu instructs various parts called device controllers to transfer data between secondary memory and the main memory the cpu accepts the data from the input unit processes it and gives the result/output to the output device the data/result can be stored for the use by storing it in the secondary memory the total operations of the computer is synchronized and controlled by the cpu the processing capacity of a computer is measured in terms the amount of data processed by the cpu in one operation the cpu has three important sub units 1 arithmetic-logic unit 2 control unit 3 memory unit eduproz page 13

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introduction to information technology arithmetic-logic unit alu the alu is an electronic circuit used to carry out the arithmetic operations like addition subtraction multiplication and division this unit carries out logical operations like greater than less than equal to etc it performs the operation on the data provided by the input devices a comparison operation allows a program to make decisions based on its data input and results of the previous calculations logical operations can be used to determine whether particular statement is true or false the alu operates on the data available in the main memory and sends them back after processing again to main memory control unit the control unit coordinates the activities of all the other units in the system its main functions are to control the transfer of data and information between various units and to initiate appropriate actions by the arithmetic-logic unit conceptually the control unit fetches instructions from the memory decodes them and directs them to various units to perform the specified tasks memory unit the main memory is also called primary memory is used to store data temporarily although the cpu is the brain behind all the operations in the computer it needs to be supplied with the data to be processed and the instructions to tell it what to do once the cpu has carried out an instruction it needs the result to be stored this storage space is provided by the computer s memory data provided by the input device and the result of that processed data is also stored in the memory nit this main memory is like a scratch pad the storage capacity of the memory is generally measured in megabytes 8 bits 1 byte 1024 bytes 1 kilobyte kb 1024 kilobytes 1 megabyte mb 1024 megabytes 1 gigabyte gb different kinds of primary memory are random access memory ram and read only memory rom you can read and write data in ram but the data is volatile or temporary that is whenever the power is switched off the contents of ram is lost so its is required to store the data in the secondary memory if the data is required for the future use but you can only read the data from rom and you can not write any thing into it and the data is permanent the manufacturer himself has written the data in it initially secondary memory eduproz page 14

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introduction to information technology this is the permanent memory the data stored in it is permanent but you can delete the data if you want there are different kinds of secondary storage devices available few of them are floppy disks fixed hard disks and optical disks etc floppy disk this is one of the most common storage medium used today in computers it is flexible circular plastic disk coated with magnetic material the disk has two surfaces and data will be stored/retrieved from both the surfaces circular tracks are recorded on each of the surfaces a track is further subdivided into sectors these tracks sectors and surfaces of disks are used to identify the place where the data will be written/retrieved the information can be stored or retrieved by inserting the floppy disk in the disk drive present in the computer the above shown floppy disk is 3.5-inch floppy disk which has the capacity of 1.44 mb fixed hard disk these are smooth metal plates coated with a thin film of magnetic material a set of such magnetic plates is fixed to a spindle one below the other to make up a set of disks this disk pack is sealed and mounted on a disk drive the disk drive consists of a motor to rotate the disk pack around its axis at the speed of about 7200 rotations per minute rpm the drive also has a set of magnetic heads mounted on arms the arm assembly is capable of moving in and out in radial direction information is recorded on the surface of a disk as it rotates about its axis circular tracks are recorded on each of the surfaces a set of corresponding tracks in all surfaces of disks is called a cylinder a track is further subdivided into sectors these cylinders sectors and surfaces of disks are used to identify the place where the data will be written/read these have the capacities in 40 giga bytes gb 80 gb etc eduproz page 15

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