Computer Fundamentals - 8th Edition

Concepts, Systems & Applications

Pradeep K.Sinha

• Editorial: BPB Publications
• Año: 2004
• ISBN:
  9788176567527
• Categoría: Computer Science
• Categoría: Operating Systems

Dive into the fundamental, evolving, and emerging Applications of computer

Key Features
? Characteristics, Generations, Classification, and Basic Organization of computers.
? Number systems, Computer codes, Binary arithmetic, Boolean algebra, and Logic circuits.
? Internal structure and functioning of CPUs, Memory, Secondary storage devices, and I/O devices.
? Computer software, its various types with examples, and commonly used tools and techniques for planning,
development, implementation, and operation of software systems.
? Computer languages, Computer networks, Operating systems, and Database technologies.
? The internet, Internet of Things (IoT), Multimedia computing systems, its applications, and many more

Description
The eighth edition of this widely popular book is designed to introduce its readers to important concepts in Computer Science, Computer Applications, and Information Technology, through a single book. With numerous illustrative diagrams, practical examples, chapter summaries, end-of-chapter questions, and glossary of important terms, and lecture notes presentation in slides, the book is designed to serve as an ideal textbook.

What you will learn
The new edition has several new topics such as Python, Internet of Things (IoT), 4G, 5G, iOS, Android OS, Watch OS, 3D printing, Solid State Drive (SSD), etc., thereby introducing the readers to the latest trends in computing.

Who this book is for
Anyone who wishes to develop a clear understanding of computer hardware, software and applications including? Undergraduate students of all disciplines (science, commerce, management, arts, etc.)
? Engineering students of all branches
? Applicants preparing for various competitive examinations
? All types of professionals who use computers in their jobs
? Participants of various training programs in computing

Table of Contents
1. Introduction
2. Basic computer organization
3. Number systems
4. Computer codes
5. Computer arithmetic
6. Boolean algebra and logic circuits
7. Processor and memory
8. Secondary storage devices
9. Input-output devices
10. Computer software
11. Planning the computer program
12. Computer languages
13. System implementation and operation
14. Operating systems
15. Application software packages
16. Business data processing
17. Data communications and computer networks
18. The internet and internet of things
19. Multimedia
20. Classification of computers
21. Introduction to C programming language

CHAPTER 1

Introduction

The word “computer” comes from the word “compute”, which means, “to calculate”. Hence, people usually consider a computer to be a calculating device that can perform arithmetic operations at high speed. Although the original objective of inventing a computer was to create a fast calculating device, we now define a computer as a device that operates upon data because more than 80% of work done by today's computers is data processing. Data can be anything like bio-data of applicants including their photographs, when computer is used for short listing candidates for recruiting; marks obtained by students in various subjects when used for preparing results; details (name, age, sex, etc.) of passengers when used for making airline or railway reservations; or number of different parameters when used for solving scientific research problems, etc. Notice from the examples that data can be numerical (only digits), alphabetic (only alphabets), alpha-numerical (mixture of digits, alphabets and special characters), text, image, voice or video.

A computer is often referred to as a data processor because it can store, process, and retrieve data whenever desired. The name data processor is more inclusive because modern computers not only compute in the usual sense but also perform other functions with data that flows to and from them. For example, data processors may gather data from various incoming sources, merge (process of mixing or putting together) them all, sort (process of arranging in some sequence - ascending or descending) them in the desired order, and finally print them in desired format. Notice that none of these operations involves arithmetic computations in the usual sense but a computer is the most suitable device for performing them.

The activity of processing data using a computer is called data processing. Data processing consists of three sub-activities: capturing input data, manipulating the data, and managing output results. As used in data processing, information is data arranged in an order and form that is useful to people receiving it. Hence, data is raw material used as input to data processing and information is processed data obtained as output of data processing (see Figure 1.1).

Figure 1.1. A computer (also known as data processor) converts data into information.

CHARACTERISTICS OF COMPUTERS

Increasing popularity of computers has proved that it is a very powerful and useful tool. The power and usefulness of this popular tool are mainly due to its following characteristics:

1. Automatic. An automatic machine works by itself without human intervention. Computers are automatic machines because once started on a job, they carry out the job (normally without any human assistance) until it is finished. However, computers being machines cannot start themselves and cannot go out and find their own problems and solutions. We need to instruct a computer using coded instructions that specify exactly how it will do a particular job. Some of the other characteristics of computers (such as speed and accuracy) are because they are automatic and work on a problem without any human intervention.
2. Speed. A computer is a very fast device. It can perform in a few seconds, the amount of work that a human being can do in an entire year - if he/she worked day and night and did nothing else. In other words, a computer can do in a few minutes what would take a man his entire lifetime.
   While talking about the speed of a computer we do not talk in terms of seconds or even milliseconds (10-3) but in terms of microseconds (10-6), nanoseconds (10-9), and even picoseconds (10-12). A powerful computer is capable of performing several billion (109), even trillion (1012), simple arithmetic operations per second.
3. Accuracy. In addition to being very fast, computers are very accurate. Accuracy of a computer is consistently high and the degree of its accuracy depends upon its design. A computer performs every calculation with the same accuracy.
   However, errors can occur in a computer. These errors are mainly due to human rather than technological weaknesses. For example, errors may occur due to imprecise thinking by a programmer (a person who writes instructions for a computer to solve a particular problem) or incorrect input data. We often refer to computer errors caused due to incorrect input data or unreliable programs as garbage-in-garbage-out (GIGO).
4. Diligence. Unlike human beings, a computer is free from monotony, tiredness, and lack of concentration. It can continuously work for hours without creating any error and without grumbling. Hence, computers score over human beings in doing routine type of jobs that require great accuracy. If ten million calculations have to be performed, a computer will perform the last one with exactly the same accuracy and speed as the first one.
5. Versatility. Versatility is one of the most wonderful things about a computer. One moment it is preparing results of an examination, next moment it is busy preparing electricity bills, and in between, it may be helping an office secretary to trace an important letter in seconds. All that is required to change its talent is to slip in a new program (a sequence of instructions for the computer) into it. In brief, a computer is capable of performing almost any task, if the task can be reduced to a finite series of logical steps.
6. Power of remembering. As a human being acquires new knowledge, his/her brain subconsciously selects what it feels to be important and worth retaining in memory. The brain relegates unimportant details to back of mind or just forgets them. This is not the case with computers. A computer can store and recall any amount of information because of its secondary storage (a type of detachable memory) capability. It can retain a piece of information as long as a user desires and the user can recall the information whenever required. Even after several years, a user can recall exactly the same information that he/she had stored in the computer several years ago. A computer forgets or looses certain information only when a user asks it to do so. Hence, it is entirely up to the user to make a computer retain or forget some information.
7. No I. Q. A computer is not a magical device. It possesses no intelligence of its own. Its I. Q. is zero, at least until today. It has to be told what to do and in what sequence. Hence, only a user determines what tasks a computer will perform. A computer cannot take its own decision in this regard.
8. No feelings. Computers are devoid of emotions. They have no feelings and no instincts because they are machines. Although men have succeeded in building a memory for computer, but no computer possesses the equivalent of a human heart and soul. Based on our feelings, taste, knowledge, and experience we often make certain judgements in our day-to-day life whereas, computers cannot make such judgements on their own. They make judgements based on the instructions given to them in the form of programs that are written by us (human beings).

Figure 1.2 provides a summary of characteristics of computers.

Sr. No.	Characteristics	Description
1	Automatic	It carries out a job normally without any human intervention
2	Speed	It can perform several billion (109), even trillion (1012), simple arithmetic operations per second
3	Accuracy	It performs every calculation with the same accuracy
4	Diligence	It is free from monotony, tiredness, and lack of concentration
5	Versatility	It can perform a wide variety of tasks
6	Memory	It can store huge amount of information and can recall any piece of this information whenever required
7	No I. Q.	It cannot take its own decisions, and has to be instructed what to do and in what sequence
8	No feelings	It cannot make judgments based on feelings and instincts

Figure 1.2. Characteristics of computers.

EVOLUTION OF COMPUTERS

Necessity is the mother of invention. The saying holds true for computers too. Researchers invented computers because of man's search for fast and accurate calculating devices.

Blaise Pascal invented the first mechanical adding machine in 1642. Later, in the year 1671, Baron Gottfried Wilhelm von Leibniz of Germany invented the first calculator for multiplication. Keyboard machines originated in the United States around 1880 and we use them even today. Around the same period, Herman Hollerith came up with the concept of punched cards that computers used extensively as input medium even in late 1970s. Business machines and calculators made their appearance in Europe and America towards the end of the nineteenth century.

Charles Babbage, a nineteenth century Professor at Cambridge University, is considered the father of modern digital programmable computers. He had employed a group of clerks for preparing mathematical and statistical tables. Babbage had to spend several hours checking these tables because even utmost care and precautions could not eliminate human errors. Soon he became dissatisfied and exasperated with this type of monotonous job. As a result, he started thinking about building a machine that could compute tables guaranteed to be error-free. In this process, Babbage designed a “Difference Engine” in the year 1822 that could produce reliable tables. In 1842, Babbage came out with his new idea of a completely automatic Analytical Engine for performing basic arithmetic functions for any mathematical problem at an average speed of 60 additions per minute. Unfortunately, he was unable to produce a working model of this machine because the precision engineering required to manufacture the machine was not available during that period. However, his efforts established a number of principles that are fundamental to the design of any digital programmable computer.

A major drawback of the early automatic calculating machines was that their programs were wired on boards that made it difficult to change programs. In 1940s, Dr. John Von Neumann introduced the “stored program” concept that helped in overcoming hard-wired program problem. The basic idea behind this concept is that a sequence of instructions and data can be stored in memory of a computer for automatically directing flow of operations. This feature considerably influenced development of modern digital computers because of ease with which different programs can be loaded and executed on a single computer. Due to this feature, we often refer to modern digital computers as stored program digital computers.

Figure 1.3 provides basic information about some of the well-known early computers.

COMPUTER GENERATIONS

“Generation” in computer talk provides a framework for the growth of computer industry based on key technologies developed. Originally, it was used to distinguish between hardware technologies but was later extended to include both hardware and software technologies.

The custom of referring to computer era in terms of generations came into wide use only after 1964. There are totally five computer generations known until today. Below we describe each generation along with its identifying characteristics. Although there is some overlap between different generations, the approximate period shown against each is normally accepted.

In the description below, you will come across several new terminologies. Subsequent chapters will deal with these terminologies in detail. The idea here is to provide an overview of the major developments and technologies during the five generations of computers and not to explain them in detail. Hence, this section provides an overview of what all you are going to learn in this entire book.

First Generation (1942-1955)

The early computers of Figure 1.3 and others of their time were manufactured using vacuum tubes as electronic switching device. A vacuum tube [see Figure 1.4(a)] was a fragile glass device using filaments as a source of electronics and could control and amplify electronic signals. It was the only high-speed electronic switching device available in those days. These vacuum tube computers could perform computations in milliseconds and were known as first-generation computers.

System name	Approximate period	Built by	Key features
The Mark I Computer	1937-44	Howard A. Aiken of Harvard University in collaboration with IBM	It was an electro-mechanical device; it used over 3000 electrically actuated switches; it was about 50 feet long and 8 feet high; it could perform addition, subtraction, multiplication, division and table reference on numbers as large as 23 ...