INFORMATION TECHNOLOGY BOOK PDF
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this combination of traditional computer and com- munication technologies. The purpose of this book is to help you use and understand information technology. Introduction to Information Technology incorporates the major changes that have taken place in the field of information technology, including not only the latest. Browse science publications on Computers and Information Technology from the Viewing 1 - 10 of books in Computers and Information Technology.
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.
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.
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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 buy 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. Banks, supermarkets, leisure centres, libraries and even the police ply us with more.
Newspapers, television and the radio present us with their own ideas of what information should be. In many instances, however, we may not agree with their conclusions. We all understand and deal with this accordingly when extracting news from the media, for example. Yet many of our organizations consider information to be something more. They see it as a vital resource, to be managed like any other valuable resource. How it is used and disseminated through the available technology can determine how efficient, and indeed effective, an organization is.
Information is important, we cannot operate without it. But more than this, we are discovering that our ability to process it by increasingly sophisticated technological means is fundamentally changing the way that employees perceive their organizational environment. The consequences of this could be either to break down established functional controls or indeed to enhance them by becoming super-efficient. Much will depend upon the characteristics of the organization before implementation.
How, for instance, can we possibly design an adequate information system if we do not understand the nature of information? The answer to this lies, in part, with the conventional wisdom of the day. Managers, like everybody else, develop their views through exposure to established ideas. Thus, the way in which they understand information will influence the way in which they treat it. Anecdotal prescriptions abound as guidelines to the way presented for all who care to listen.
These arise from a blanket of professional and academic 24 A Handbook of Information Technology thinking which surrounds the business environment and provides remedies for action. We could categorize all these ideas into two bodies of thought, two paradigms. The first could be termed the resource-driven paradigm.
This is because its central theme in understanding information is the continuity and consistency of the information itself.
It is very much in vogue at present. The second body of thought is the perception-driven paradigm. Information is seen as an abstract concept, the product of individual perception. It is a temporary phenomenon and as such belongs only to the receiver.
The difference is not merely one of academic debate. Managements adopting one or the other can affect the design of their organizations.
If information is considered to be a resource then resulting systems are usually more centrally controlled, the assumption being that all information is corporate property. Whereas information considered to be personally owned is seen as being outside the formal structure.
Within the framework of this paradigm the view of information is coloured by its use as a resource. Like any other resource it can be tapped at any time with the certainty of achieving a predictable value from it.
There are a range of propositions available which seeks to explain information. Each proposition has a consequence for organizational design.
Listed below are those major themes and what their implications might be on business. Herbert A. Simon took the view that information, along with energy, constitute the two basic currencies of our society. We need energy to breathe, to move, to think, to live. But this alone is not enough. We need to know when to breathe, when to move and how to think. Information provides us with that knowledge.
To adopt this perspective is to interpret information as an independent entity. It is all about us waiting to be picked up and used. There may be minor variations in its interpretation by different individuals, but consistency can be easily achieved through better training.
Specific sets of information, such as finance information, are given a unique value by organizations which are usually based upon departmental rather than individual needs. Particular information is thus attached to particular departments.
This allows information to be generally accessible because perceptions of it are bound by the formal departmental framework. Information is then tied into that framework and cannot be used legitimately within any other context, thus guarding its consistency. What is excluded, therefore, is an important role for the individual receiver. This is not to suggest that information cannot be perceived by individuals. However, information can be received automatically without an individual having to understand it.
For example, through training an employee could process production statistics without knowing what they mean. In this case it is the functional process through its formal procedure that is acting as the receiver rather than the individual. An accounting process, for instance, responds to specific inputs without anyone having to understand them.
A motor car responds to certain information transmitted through mechanisms such as the throttle, steering wheel or brake. Both of these examples are designed to act as receivers to specific information. By implication, information can be transmitted to any receiver that logs into the particular transmission.
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In the same way as a radio picks up a station when it is switched on, the right form will pick up the right information. And like radio waves, information is omnipresent, only needing the correct tuning. Such a view allows information the continuity and consistency required to be regarded as a resource. It also allows a further proposition.
The design of any formal information system must assume that information does not change during transmission. It can, however, be transformed from data or other information sets before transmission. Within such a framework it is the transmitting functions departments, processes, etc. The information receiving functions also departments, processes, etc. An information network between functions Each function, however, can be both transmitter and receiver of information, and together with other functions will form part of an integrated network Figure 1.
The functions are tied by their simultaneous roles as information receivers and transmitters, thereby being prevented as much as possible from deviancy in their information usage. Consequently, business organizations are driven by those functions which transmit information. The higher the value that a particular set of information is given, the more important will be its relating transmitter function.
For 26 A Handbook of Information Technology example, the finance department could both transmit and receive information. Indeed, each job function within that department could also do the same. A cost clerk, for instance, receives information from the factory floor which he then processes into other information and transmits to some other source, perhaps management. The value of the information he processes will depend upon the utility his organization has placed upon it. If the utility is high, then the prestige attached to the transmitting function will also be high irrespective of job complexity.
In the same way, if a department has a great number of important information transmitters within its control, then it too will be prestigious and possess influence. Perception-driven Paradigm The perception-driven paradigm does not consider information to be a resource. Individuals or groups are seen to own their information.
What belongs to the organization are the data sets, the facts and figures specific to certain functions. For instance, data on how an organization is performing in its market quite obviously belong to that firm. Management can control this indirectly through training, but they cannot directly control the thought processes which turns data into information. Once again, there is a collection of propositions or ideas about information which formulate a general approach.
Adherence to this paradigm, as in the previous paradigm, may not necessarily be by conviction but rather by default because people not treating information as a resource automatically form part of this group.
However, there are others who are members by conviction. Information is said to be receiver-dependent, in that, any set of information can be considered to be information only if it is recognised as having value by a particular individual. Thus, a river flooding may be information to someone who lives on its banks but of no consequence to someone living several miles away. It would be difficult, therefore, to understand information as a group or organizations property since its determination is subjective.
Management teams have implemented computer technology and in so doing also developed their information sets into a resource. Information is no longer seen as a resource; indeed its treatment as such is often seen as the culprit and not the technology itself. Computer personnel, for example, have long known of the distinction. Information is seen by them as processed data. The two are interrelated, data being the input to a process, and information the output.
In the same way that an output of one system can form the input of another, information from one system can form the data of another. This is consistent with treating information as a resource.
Perceptually-conceived information on the other hand is not the consequence of a formalized process. Data are a factor, but then so are other aspects such as individual traits, culture, structure and political processes. The relationship between data and information is, therefore, not so strong. This contradicts the objectives implied by the creation of management information systems and data processing.
The former allows the individual access to established information, whilst the latter converts data into information. Since the production of information cannot be formalized there is no point in trying to achieve it. Systems should, therefore, be designed to produce the most accurate and readable data in order to enhance easy conversion into information. When Ligomenides describes information as a fundamental force, he should be referring to data. Levitan, on the other hand, is correct in claiming information to be dynamic and continuously evolving.
The logic of these two views can be seen when data and information are differentiated. It is only data which is time-independent, and therefore unchanging and static— a fundamental force. By this we mean that data retains a constant empirical value: a fact is a fact and cannot be altered. Information, on the other hand, can be altered and changed.
It is time-dependent and thus its value can alter from one moment to the next. It is, indeed, time and utility which transform data into information. If at a particular time a set of data is useful to an individual then it can be described as information.
Equally, at another time the same set of data may not have utility and therefore not be information.
The data themselves have not changed in any way, remaining always constant. Information is in reality the consequence of a complex psychological process which transforms perceived data, into usable thought inputs.
It is, therefore, data which the individual receives from the environment, the brain which transforms these data into information. No formal system can directly pre-empt this stage; thus no formal system can transform data into information. Data can be transformed into different data, transmitted and received. For example, production data submitted to the cost department and processed 28 A Handbook of Information Technology into second generation costed production data, which are in turn submitted to the financial director.
Information is transformed, in part, from data; it can only be received and never transmitted. The financial director may attach value to costed production data and thus receive it as information.
There cannot be information systems because information is so transient. At another time that perception may be different. Information systems cannot work in this way.
Their assumption must be that information is not transient but consistent. Quite obviously information systems do exist in one form or another.
They may not be what they claim to be but they are nevertheless working. Is it worth arguing the difference? The answer to that lies within ourselves. Our actions and behaviour, and consequently our organizations, are governed by our perceptions. If, therefore, we understand information to be permanent rather than transient then how we organize ourselves will be coloured by that.
We will design systems which use information as a resource and expect it to be totally consistent. Structural Implications The difference between these two paradigms may seem subtle, and in terms of information usage it may well be. However, NBS research indicates that the effects upon organizational design can be major. Structural characteristics consequent upon individually-owned information, for instance, can adopt two extremes.
On the one hand they can be organic and informal adhocracies whereby all members are seen as contributing equally, each possessing a particular range of techniques to interpret data, whilst at the other extreme there are formal and mechanistic organizations bureaucracies.
The rigidities of structure stifle any use of information as a resource, so by default such processes are left to the individual. These contrast with the resource-driven paradigm in which the structural characteristics of organizations are seen to be centrally orientated, with spheres of influence at the periphery, their importance dependent upon the perceived value of particular sets of information.
Storage Devices Secondary Memory: These are also known as auxiliary memory or backup storage device. These are the slowest memories in memory hierarchy.
They are very cheap and are used in bulk usually in terms in Giga Bytes. These are normally used for storage the big programs and huge software. The secondary memory is permanent in nature i. Secondary storage devices being permanent in nature can also be used for transportation of data from one computer to another.
Magnetic Disk: Magnetic Disk is a rigid plastic disk coated with an oxide for easy magnetization. The working principle is similar to the functioning of the gramophone records. The sound waves are converted to electromagnetic signals and stored on the Information Technology for Managers record surface and while playing reverse process occurs. In magnetic disk the data stored is in the form of magnetic spots.
Magnetic disk is, infact, a pack of many plastic disks. These disks are placed together over one another to form a hard disk. One magnetic disk pack may consist of 5 or more disk which can be used from both the sides.
All these disks are covered by a metallic shield to form one hard disk. Hard Disk: A hard disk is a magnetic disk on which one can store computer data. Hard disk hold more data and a faster than floppy disk. A single hard disk usually consists of several platters. Each platter has the same number of tracks, and the track location that cuts across all platters is called a cylinder. Hard disks are less portable than floppies, although it is possible to buy removable hard disk.
Usually they consist of a single removable plastic or metal disk coated on one side with tellurium. They are protected by a 1 mm layer of transparent plastic. In this storage device the information is stored in compact form.The amended program is given in Figure 3. Recoverability as a First-Class Security Objective: Taking you from installation on Windows or Linux through to advanced virtual machine features, you'll be setting up a test environment in no time.
The capacity of hard-disk drive ranges from 10 MB to MB in a single drive. They are very cheap and are used in bulk usually in terms in Giga Bytes. Opportunities and Options Consensus Study Report.
Both information and size are considered to be contingents, that is variables which affect the characteristics of an organization. The probable future has become one of millions of small yet powerful computers, controlling virtually every machine and appliance.
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