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INTRODUCTION TO INFORMATION TECHNOLOGY BOOK PDF

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Technology (IT). Dheeraj Mehrotra Information is data processed for some purpose. • Information can only be database / address book. - DVD / CD Player . The Concept of Information Technology 8th Edition. This book written by Tariq Mahmood & Imran Saeed, reviwed by Tasleem Mustafa and. Information Technologies are systems of hardware and/or software that capture, downloading airline tecket; Ordering books; Electronic banking/ stock market.

The probable future has become one of millions of small yet powerful computers, controlling virtually every machine and appliance. These are distributed in every home, on every desk, in every workshop; many of them connected in a maze of small and large networks, much like the present telephone network.

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This enables individual computers to communicate, sharing information in a gigantic distributed data-base, and gaining, through distributed processing, computational power whose extent is yet difficult to gauge; all this following the individual requirements and choices of the owner or operator of each machine.

Increasingly, we are confronted, not only with the results of the use of computers Introduction 5 throughout industry, commerce, banking, advertising, science, the communications industry, newspapers, airlines, and hospitals; but with the realistic possibility of downloading computer power for our own small enterprises, offices, and homes.

This may be done in a variety of ways; but in all of them, the real cost of computation is constantly diminishing. Computer programming is likely to become the literacy medium of the third millennium AD. Elementary schools may well be teaching it before long, and we might be well advised to gain at least a smattering of knowledge of computers and of programming competence, especially since computer languages and programming environments are becoming increasingly helpful and friendly to the uninitiated user.

A computer is a machine for the automatic processing of information.

Historically, this information was numerical, and computers were machines for doing arithmetic. Unlike the simpler calculating machines, which can perform only one elementary arithmetic operation at a time, they need to be told what to do next usually by suitable button-pushes ; computers can be given a list of operations to perform often with branching and repetitions, depending on tests of sign or value included among the operations , which they will then execute in proper sequence without further intervention.

This sequence of instructions is called a program. A digital computer stores its information in the form of words, finite ordered sets of digits, each of which can have only one of a finite set of values.

Considerations of simplicity, reliability and economy dictate that electrical engineers should design computers to consist of a great number of similar pieces of circuitry, each of which can only be in one of two states, usually denoted by 0 and 1. Such binary digits or bits are the elements of which computer digital representation is built.

A row of eight bits is called a byte, and the majority of computers have their storage of information organized in words of one, two, four, or eight bytes 8, 16, 32, or 64 bits. These may now be viewed as the 16 possible digits of a representation the hexadecimal, or hex , which is much more compact and humanly intelligible than a long string of zeroes and ones. These are, essentially, 1. The OCU keeps track of the memory location of the next instruction to be executed, and analyzes the current instruction, so as to activate the proper operation of a memory transfer, nonsequential jump by appropriately changing the address of the next instruction , input or output of information, or computation performed by the ALU , as is indicated by the instruction code.

Such registers are usually called accumulators, and they are normally double-length since the product of two k-bit numbers is a 2k-bit number. Other LM registers are used for counting eg. Originally, the CPU was a sizable piece of electronics, hand-assembled and highly complex. With the advent of micro-miniaturization of circuitry, printing, and photographic techniques, and the mass production of components only the largest computers mainframes are built in the old way.

Smaller systems generally have the entire CPU on a single chip. Among these, the name microcomputer is now applied to those with less than a million words of memory and a word length of one or two bytes; the name minicomputer applies to the larger machines, with two to four-byte words and one to a hundred million words of memory. The smallest micro is probably more powerful than the big computers used by universities and industry in the s. The main memory mm consists of magnetic or electronic components which store the information both data and instructions needed by the computer.

The individual words are directly addressable from the CPU by number rather like houses in a street , and their contents are retrievable in very short times, of the order of the operation time of the CPU ranging from fractions of a nanosecond, or one billionth of a second, for the fastest mainframes to several microseconds, or millionths of a second, for the slower micros. This is often referred to as high-speed storage or random-access memory RAM.

While most of the mm is erasable and may be changed at will, some memory is used to store constants and often-used utility programs and is not erasable by the CPU: such memory is called read-only memory ROM. Sometimes this is optional and can be plugged into the computer : this is called firmware. Thus, we write 16K for 2U and V4M for Almost all computer instructions comprise an operation code usually one byte long, allowing possible operations to be specified , followed by 8 A Handbook of Information Technology an operand reference number, index, or address of variable length since some operations require more data than others; for instance, the STOP instruction needs no operand, so it is one byte long.

Access times can be quite good for sequential access, along the tape, but random access time is poor at best, running to seconds or even minutes. Economy and a virtually unlimited total storage capacity on numerous cassettes or reels; but only as many units as one has on-line tape-drives are actually accessible without human intervention are the only advantages.

Disk Memory When we wish for practically useful EM, combining large capacity with relative economy and speed of random access, we must turn to drum or disk memory; and, nowadays, the former have been practically replaced by the latter. Disk memory is of two types: floppy disk and hard disk, the first being the cheaper, slower, smaller-capacity option. The information is stored on concentric circular tracks not on a single spiral track, as on a sound record , on one or both sides of the disk.

The number of tracks and the number of bytes per track vary the density increasing with precision of engineering, and so with cost of the drive , but the total capacity of a floppy disk is in the range of 50KB to 1MB.

The disks rotate at, typically, rpm, and access time is governed by the time required to place the movable head on the right track, a fraction of a second, plus the fifth of a second taken by the head to traverse the circumference of the track, in search of a record; thereafter, consecutive bytes are accessed at some thousands per second.

Hard disks are rigid and have larger diameters. There are drives which range from anything from one to a dozen disks, rotating at about ten times the Introduction 9 speed of floppy-disk drives and so diminishing the access time of records in a track with one or several heads. Fixed-head drives naturally must have a head for each track which costs more , but save head-movement time in random access. Winchester disks are movable-head drives with sealed-in disks, where the heads ride very close to the disk, cushioned by the layer of air between.

In floppy-disk drives, the head actually rides on the disk, eventually wearing it out. The capacity of hard-disk drive ranges from 10 MB to MB in a single drive. Some movable-head hard-disk drives have removable disks or diskpacks, allowing for greater library storage.

Increasingly in large computers, and almost universally in small ones, the main input is from the keyboard of a terminal. This is much like a typewriter keyboard, and depressing any key sends an 8-bit code to the computer. It is quite common for the computer to be connected to several terminals, all competing for its attention.

This is called time-sharing. The computer cycles around the terminals, look for their several inputs while dividing its CPU time among them. The main output of the computer is to the display devices of the terminals; these are either video displays cathode ray tubes, CRT, just like the screens of blackand-white or color TV sets; indeed, simple micros sometimes use ordinary television sets as display devices or printers in so-called hard-copy terminals.

Of course, the computer may be connected to additional video displays and printers, of different qualities, as well as to plotters, a kind of printer for drawing graphs and diagrams. Many types and speeds of printers exist. Output from the computer can similarly follow the reverse process, yielding visible or audible results, or the control of mechanical or electrical equipment. Thus, computers can draw pictures often, moving pictures , make music and other sounds, and can control appliances, machinery, and whole 10 A Handbook of Information Technology manufacturing processes.

It is also possible to connect several computers in this way. This is called the formation of a computer network. Of course, computers may also be connected by cable, fibre-optics, or microwave link. Many networks do not have a central computer at all; but are simply a collection of independent computers linked for the sharing of information and, sometimes, computing capabilities. Often, they permit the exchange of messages computer mail and the pooling of data distributed data-base.

They may also share a common bank of memory, accessible to all. Finally, since the invention of computer networks, designers have been investigating the possibilities of computers made up of an array of CPUs multicomputer, parallel processors, distributed processing. These new ideas are very powerful and farreaching: they will probably revolutionize our ideas of computers, and of their applications, in the next few years. The various peripheral devices are connected to the CPU without examining how.

In fact, this may be done in several ways. We can simply have a separate connection or port for each device, but this limits rather severely the number of devices that may be connected to the CPU.

Another way is to have a single bus or connection to which any number of devices may be attached. The information signal must then carry an appropriate address. The bus receives all signals, and individual devices including the CPU seek out and decode only those addressed to them.

It is also possible to have a switching device, which receives addressed data and directs them to the appropriate recipient device, rather like a central post office.

The decision on what communication arrangements to adopt is made on the basis of considerations of cost, capacity, and speed. It is often the case that the several devices forming a computer or a computer network have their data coded in different ways. It is then the job of the CPU s and PPs to share the work of interpreting signals into appropriate codes for each machine. This is broadly termed the Introduction 11 problem of interfacing devices. Sometimes, the solution is to have a standard code or structure for the communications device one meets the s bus, the rs serial port, the ASCII character-code, and so on.

Another interfacing problem arises from the difference in the rate at which different devices can send and receive information this is measured by the baud rate, named after Baudot, the inventor of the first five-hole papertape code; one baud is one bit transferred per second; hence kilobaud, kb, and megabaud, Mb typical rates range from baud to kb.

One solution is to send each piece of information usually one character at a time, which takes 8 to 10 bits only when the last has been acknowledged this is referred to as a handshake ; this is sure, but slow. Another way is to use a storage buffer in which a large batch of information is accumulated for fast transmission, thus not wasting the time of the faster device.

One last kind of choice must be mentioned: some channels of communication are serial they transmit one bit at a time , while others are parallel they can transmit a byte or a whole word at a time ; the latter are obviously faster, more complex, and more expensive. When devices are connected by cable, the degree of parallel communication is exhibited in the width of a flat ribbon cable, carrying several wires, side by side, and in the number of pins in the plugs and sockets by which they are connected to the machines.

Parallel transmission is a variation on multiplexing. What we have described is generally referred to as the hardware of a computer. Inevitably, there came to be programs that were hard-wired in the now outdated phrase into the computer, in the form of ROM.

These are termed firmware. A computer without software is a helpless set-of circuits, and the expertise required to create the basic software that will bring the machine to useful life is comparable to that required to design the machine itself.

Indeed, these days, computers are designed in cooperation between computer architects, who design what the computer will do, hardware engineers, who design how it will be constructed to be able to do it, and software engineers, who design and program the operating system that will run the machine.

Beyond this, the computer will also need application software of many kinds, to enable it to do a variety of jobs, such as file-handling, accounting, statistics, payrolls, inventories, complex graphic displays, games, and so on. Typically, the application software is written i. Computer Languages The CPU of any computer is designed to accept and execute a specific set of operation codes op-codes , ranging in number from a dozen or so to several hundred.

Different makes and models of computers and microprocessors may have entirely dissimilar op-codes; but the operations that they represent are much more alike than different, both through functional necessity and historical development. The interpretation of the op-codes is built into the hardware of the OCU though sometimes the details of interpretation may be modified by the user through what is called microcoding , and it is part of this interpretation that the complete instruction being decoded contains a certain amount of further information such as parameters, indices, and one or more memory addresses.

The aggregate of possible machine instructions is called the machine language. Indeed, the slightest error in a program almost always leads to an error in its output usually a fatal error! It is estimated that, in the production of a working program, the debugging time may be two to four times as long as the time it takes to plan and write the program initially. To give the reader a feeling for the nature of machine language, we present a simplified, fictitious, but typical, machine language specification.

Our computer has two bit accumulator registers acc , X and Y, which may be coupled into a single bit ace XY, with X holding the more and Y the less significant digits; these are attached to the ALU; and a program control register pc Z, also of 16 bits, attached to the OCU, which contains the address of the next instruction to be executed. Finally, a bit code b refers to each of the 16 bits in a word bit 0 being the least significant-rightmost and bit 15 the most significantleftmost. In some cases, the codes a, d, p, and b are interpreted somewhat differently, depending on the particular op-code c.

As an example of a very simple computer program, we consider the solution to the following computer problem. Our computer is to be fed a sequence of one thousand bit numbers at input port 9 these may be keyed in by hand or fed in by a digitizer connected to some experiment.

They are to be stored in memory words with addresses , , ,. Their sum is to be computed and stored in address and output to a printer through output port 2. The program is to be stored beginning at address 0 in the memory. Again, what is important about this example is not its detailed form, but the difficulty of its interpretation, and therefore also the difficulty of verification and debugging.

The programmer must deal with a mass of details that are of a purely mechanical nature and have no relevance to the problem being solved. Higher-level languages After some introductory description of an imaginary computer, and especially of its CPU, and the establishment of some essential notation. Presented with a set of arithmetic and other transformations required by potential users of a proposed new computer, the electronic and logical design engineers seek the simplest circuitry that will execute operations sufficient to 14 A Handbook of Information Technology generate all the required transformations.

Circuits must be simple to be fast, efficient, reliable, and cheap. However, when an instruction has 16 or more bits, most of which should for the sake of efficiency, have some significant effect; the exact and complete specification or the action induced by it may well be somewhat forbiddingly intricate!

And indeed, simplicity of circuitry does not usually lead to simplicity of use. An ample of a program in this machine language, which takes 16 instructions and 28 bit words of memory storage, to read in one thousand numbers, store them in consecutive memory locations, sum them, and print out the sum. However, please note that the English description of what the program does though much easier to say and comprehend itself requires characters, each equivalent to 8 bits; so that it is almost twice as long as the machine-language program.

Indeed, the difficulty of the latter lies not in its length, but in its alien and opaque form of expression of what it does. The first improvement on machine language was assembly language. This is not very different from machine language, but removes the most glaring and trivial irritations.

First, instructions may be labelled, so that one no longer needs to count lines to address jump instructions; one jumps to the label. This is also a great help when one wishes to insert additional instructions, either to correct or modify a program every jump need not be changed.

Second, memory may be labelled, so that numbers may be stored in symbolic addresses and retrieved therefrom, leaving it to a computer program to assign actual storage.

Third, the entire program becomes relocatable anywhere in the computer memory. Finally, and perhaps more trivially, the op-codes may be replaced by abbreviated mnemonics, and the instruction layout may be relaxed, using punctuation marks.

Of course, a program written in assembly language is no longer directly intelligible to the computer or executable by it. The assembly language instructions correspond, one-to-one, to machinelanguage instructions.

For example, we may denote memory locations by one, two, or three lower-case letters both for labelling instructions and naming variables.

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A numerical address will still be allowed. Absolute addresses i. With relocatable programs and symbolic addresses, they are no longer useful.

Instruction labels will precede the instruction and will be terminated by a colon :. Spaces will be ignored. Op-codes will be denoted by strings of capital letters and terminated by a comma , , which will also separate multiple arguments. A sample specification of assembly language op-codes is shown in Figure 1.

Italic letters p, x, or b denote numbers possibly in quotes, to denote absolutes or variables names possibly in parentheses, to denote indirect addressing , and are interpreted according to the op-code e. Again, the reader must remember that it is not the particular details of our specifications that are important or memorable but the kind and degree of detail occurring. Here, numbers are given in decimal notation.

Note the tremendous improvement in direct legibility of the program in comparison with the binary strings. As an exercise, the readers may wish to try to modify the program so as to allow for the possibility that the sum of the numbers might occupy more than 16 bits.

In machine language this requires no less than 12 changes and seven shifts of memory location. The amended program is given in Figure 3. All that shuffling of numbers in and out of the accumulators, counting and restricted testing, is not natural to us, and its mechanical nature suggests that an improvement is still possible.

Thus it was not long before programmers devised much more humanly natural languages, which are generically called higher-level or algebraic languages. There are more; and all come with a variety of versions and dialects. The characteristic that puts a language into this class is that one higherlevel instruction translates into several assembly or machine language instructions.

Beyond this, the languages differ according to the kind of program they are intended for. Once more, note that the details of the individual languages do not matter to us at this point though, if the reader ever intends to program, then some language will have to be thoroughly understood; but assume that many of my readers have no such intention ; it is their general flavor and appearance that is noteworthy; and the casual readability of the samples presented is their salient characteristic.

Fashions come and go in programming languages, not always fully based on rational arguments, and personal preferences vigorously touted. Given a higher-level language, it is necessary to have a translator program to turn it into machine or more frequently assembly language.

Such translators are of two kinds. An interpreter operates at execution time: beginning with the first instruction of the stored higher-level program, it translates it into one or more machine language instructions, which it proceeds to execute; then it reads and translates the next higher-level instruction and executes that; and so on.

If a jump is encountered in the source program as the higher-level language program is often called , the interpreter goes to the next instruction in accordance with the jump and proceeds to read, translate, and execute it, without taking into account whether it has already encountered it.

Thus, the same source instructions will have to be passed and translated a thousand times a very time-consuming and wasteful procedure. But the usually much longer object program need not be stored, and interpreters themselves tend to be shorter and simpler programs. This is why a BASIC interpreter is a natural adjunct to a microcomputer, which tends to be a little cramped for space; especially since many microcomputer users are riot interested in extremely lengthy computations. By contrast, a compiler is a program that translates a source program into an object program, the former being in higher-level language and the latter in machine or assembly language.

The program is translated as it sits in memory, not during execution; so that the problem of repeated translation is avoided. Speed is greatly increased, in general, at the expense of space in the computer memory. Of course, once a program has been compiled and proven to be free of bugs debugging is far easier in source code than in object code , the source program may be stored for future use and only the object program kept in main memory.

Compilers are available for almost all higher-level languages on almost all machines, and are essential for extensive applications. Introduction 19 Computer Software The programs, or software, available for computers fall into two classes, system software and application software.

The system software comprises those programs that are considered indispensable to the general operation of a given computer system, forming what is often termed the operating system of the computer, and generally are supplied by the manufacturer, though alternative operating systems are sometimes available from software houses.

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The applications software includes all those programs that are needed by one computer user but not by another, even if such programs are widely required, and while some manufacturers will sell applications software as optional additions to their systems , more often this is obtained from software specialists. We begin with the operating system.

This may be divided into a kernel of absolutely indispensable programs and a shell of almost indispensable, so-called utility programs. The kernel or nucleus is also sometimes termed the monitor. If the keyboard mechanism were to transmit the A for only one microsecond, on the other hand, the computer might will be busy elsewhere and miss it altogether. When the computer is ready to receive a new character, it checks the appropriate flag bit over and over, until it detects that it has been set.

The flag is always open, so the transmit pulse need only be sent once by the keyboard; but the character continues to be sent until it is acknowledged by the computer. Thus a keyboard character will neither be missed nor read repeatedly. In addition to the keyboard input already described, there will be short machine language programs for input from any other devices attached to the computer and corresponding programs for output to display screens, printers, and so on.

If, as is often the case, several users are connected to the computer, then the operating system must handle the tasks of Job-scheduling and Job accounting and billing, if this is appropriate , and the allocation of storage, in main and extended memory, and of other resources such as printers or communication lines , and the management of time-sharing as between several terminals.

Another task that is handled by the operating system is the management of user files, and their transfer between main memory and extended memory such as disk. Indeed, one sees frequent reference to disk operating systems, such is the importance of this function of the operating system. Another function of the kernel is to provide protection and security to users and to itself, both from authorized users encroaching on forbidden territory and from unauthorized users attempting to use the computer.

Another very congenial aspect of this concept is that some operating systems conduct their memory management function in such a way that the user need make no distinction between main and extended memory; this is referred to as a virtual memory system. The kernel program has to be able to display, move, modify, and search, at least the main memory, and to initiate execution at any given address, or activate any of the peripheral devices.

We now turn to the utilities provided by most operating systems. First, we have an assembler and perhaps also a disassembler, which translates a program written in machine language into the more intelligible assembly language; as well as a macroassembler, which allows the user to define his own macroinstructions in machine or assembly language , together with a selection Introduction 21 of translation programs, either interpreters or compilers, for the higher-level languages that the user wishes to employ.

The smaller microcomputers will provide an interpreter for some dialect of BASIC, since this a relatively simple language to learn and to interpret into machine or assembly language; beyond this, one must pay for additional languages.

There will be facilities for linking or chaining programs together. While the kernel will contain the rudiments of a file-handling system to create, destroy, list, locate, and transfer files , there will also be utilities for further management of these.

Such programs will sort, find among other files , search in a given file, for information specified , transform, edit, and combine files. Indeed, a good program editor can enormously facilitate the rapid and painless creation and modification of files, which include both text and programs. The line separating the kernel from the shell of utilities is purely conceptual and far from sharp. Similarly, the boundary of the entire operating system is far from definite.

What is available beyond the essentials mentioned above will be called part of any decent system by some, part of a compiled language by others, and just applications software by still others, depending on their point of view. Similarly, languages intended for scientific and engineering applications usually handle floating-point and multiple-precision arithmetic, though this may be provided even in computer hardware.

The same applies to routines for computing, for example, sines, cosines, logarithms, etc. A data-base management system DBMS may be just a glorified file-handling utility; or may be an elaborate program, cross-indexed and relational, with its own language of special commands, for answering any conceivable question about a large amount of intricately structured data.

Similarly, a graphics package may simply allow one to produce passable graphs, histograms i. The latter systems are a lot of fun to operate, and can be most helpful to draughtsmen, 22 A Handbook of Information Technology animators, film designers, and simulator-trainer designers; but they cost a bundle, and they require quite powerful computers to hold and run them. Again, there are statistical packages of various degrees of sophistication, from a mean-variance-covariance calculator, to systems able to analyse very complex sets of data by elaborate techniques, using a whole statistical computer language.

A table is presented on the video screen and each entry is allocated either a numerical value or a formula relating it to other entries.

When the data are sufficient, the resulting numbers are displayed. When an entry is changed, it and all entries depending on it are altered accordingly at once. This provides a representation of a given situation surpassed only by a graph in its impact, and a first-class planning aid. Margins may be set and the text right, left, or double justified, or set up in multi-column pages, with page numbering, indexing, and even the use of different sizes and styles of typeface, in the most sophisticated systems.

Here again, cost rises steeply, and one should download only what one will need. Beyond these programs, there lies an endless variety of unquestionable applications programs. There are programs for ballistics, boat design, analysis of molecular structure from x-ray diffraction data, tabulation of Bessel functions, simulation of naval battles and economic cycles, etc. Most of these are not in the market and only work on one machine; but there are very many programs available in the open market, produced or distributed by software houses, with various levels of efficiency, and sophistication.

Programming is a fascinating, intricate, rewarding, but unforgiving and at times infuriating occupation. We will encourage all of you who have the time to try it.

The sense of achievement when you have a working program is great; perhaps because the process is addictive and consumes much more time than you would believe possible.

TWO What is Information? Information is one of those misunderstood concepts. Yet it is at the same time one of the most used.

We go to the bus station to seek information from timetables. Data and Information 2. Acquisition of Numbers and Textual Data 3.

Acquiring Graphical Data 4. Acquiring Audio Data 5. Acquisition of Video 6. Data Storage 7. Central Processing Unit 8. Computer Networks 9. Output Devices Computer Software Data Organization Processing Numerical Data Processing and Displaying Textual Data Processing Multimedia Data Some Internet Applications Business Information Systems Electronic Commerce Societal Impacts of Information Technology.

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Snapshot About the book. Key Features.Post under Big Data and Data Science on Sat Jun 01, This book introduces you to advanced MapReduce concepts and teaches you everything from identifying the factors that affect MapReduce job performance to tuning the MapReduce configuration. Academic Aspects Very High-level Languages Computers for Individuals 8. The disks rotate at, typically, rpm, and access time is governed by the time required to place the movable head on the right track, a fraction of a second, plus the fifth of a second taken by the head to traverse the circumference of the track, in search of a record; thereafter, consecutive bytes are accessed at some thousands per second.

Introduction 2.