1
INTRODUCTION TO COMPUTER
Contents
Digital and analog computers
Characteristics of computer—Speed, accuracy, diligence, storage capability, versatility
History of computer—Calculating machines, Napier’s bones, slide rule, Pascal's adding
and subtraction machine, Leibniz's multiplication and dividing machine, punch card
system, Babbage's analytical engine, Hollerith's punched card tabulating machine
Generations of computer
o First generation (1940 to 1956): Using vacuum tubes
o Second generation (1956 to 1963): Using transistors
o Third generation (1964 to 1971): Using integrated circuits
o Fourth generation (1971 to present): Using microprocessors
o Fifth generation (present and next): Using artificial intelligence
Classification of computer—Microcomputers (desktop computer or Personal Computer
(PC), notebook computers or laptop, netbook, tablet computer, handheld computer or
Personal Digital Assistant (PDA), smart phones), minicomputers, mainframe computers,
supercomputers )
The computer system—Hardware, software, data, users
The Input-process-output concept
Components of computer hardware—Input/output unit, central processing unit, storage
unit
Application of computers—Education, entertainment, sports, advertising, medicine,
science and engineering, government, home
Why this chapter
Computers are an integral part of our lives. Wherever we are—sitting in our homes, working in
the office, driving on roads, sitting in a movie hall, staying in a hotel, etc.—our lives are directly
or indirectly affected by the computers. In this era of information, we are dependent on the
storage, flow and processing of data and information, which can only be possible with the help of
computers. The purpose of this chapter is to introduce you to the “computer”.
1.1 INTRODUCTION
Nowadays, computers are an integral part of our lives. They are used for the reservation of
tickets for airplanes and railways, payment of telephone and electricity bills, deposit and
withdrawal of money from banks, processing of business data, forecasting of weather conditions,
diagnosis of diseases, searching for information on the Internet, etc. Computers are also used
,extensively in schools, universities, organizations, music industry, movie industry, scientific
research, law firms, fashion industry, etc.
The term computer is derived from the word compute. The word compute means to calculate. A
computer is an electronic machine that accepts data from the user, processes the data by
performing calculations and operations on it, and generates the desired output results. Computer
performs both simple and complex operations, with speed and accuracy.
This chapter discusses the history and evolution of computer, the concept of input-process-output
and the characteristics of computer. This chapter also discusses the classification of digital
computers based on their size and type, and the application of computer in different domain
areas.
1.2 DIGITAL AND ANALOG COMPUTERS
A digital computer uses distinct values to represent the data internally. All information are
represented using the digits Os and 1s. The computers that we use at our homes and offices are
digital computers.
Analog computer is another kind of a computer that represents data as variable across a
continuous range of values. The earliest computers were analog computers. Analog computers
are used for measuring of parameters that vary continuously in real time, such as temperature,
pressure and voltage. Analog computers may be more flexible but generally less precise than
digital computers. Slide rule is an example of an analog computer.
This book deals only with the digital computer and uses the term computer for them.
1.3 CHARACTERISTICS OF COMPUTER
Speed, accuracy, diligence, storage capability and versatility are some of the key characteristics
of a computer. A brief overview of these characteristics are—
Speed The computer can process data very fast, at the rate of millions of instructions per
second. Some calculations that would have taken hours and days to complete otherwise,
can be completed in a few seconds using the computer. For example, calculation and
generation of salary slips of thousands of employees of an organization, weather
forecasting that requires analysis of a large amount of data related to temperature,
pressure and humidity of various places, etc.
Accuracy Computer provides a high degree of accuracy. For example, the computer can
accurately give the result of division of any two numbers up to 10 decimal places.
Diligence When used for a longer period of time, the computer does not get tired or
fatigued. It can perform long and complex calculations with the same speed and accuracy
from the start till the end.
Storage Capability Large volumes of data and information can be stored in the computer
and also retrieved whenever required. A limited amount of data can be stored,
temporarily, in the primary memory. Secondary storage devices like floppy disk and
compact disk can store a large amount of data permanently.
, Versatility Computer is versatile in nature. It can perform different types of tasks with the
same ease. At one moment you can use the computer to prepare a letter document and in
the next moment you may play music or print a document.
Computers have several limitations too. Computer can only perform tasks that it has been
programmed to do. Computer cannot do any work without instructions from the user. It executes
instructions as specified by the user and does not take its own decisions.
1.4 HISTORY OF COMPUTER
Until the development of the first generation computers based on vacuum tubes, there had been
several developments in the computing technology related to the mechanical computing devices.
The key developments that took place till the first computer was developed are as follows—
Calculating Machines ABACUS was the first mechanical calculating device for
counting of large numbers. The word ABACUS means calculating board. It consists of
bars in horizontal positions on which sets of beads are inserted. The horizontal bars have
10 beads each, representing units, tens, hundreds, etc. An abacus is shown in Figure 1.1
Figure 1.1 Abacus
Napier’s Bones was a mechanical device built for the purpose of multiplication in 1617
ad. by an English mathematician John Napier.
Slide Rule was developed by an English mathematician Edmund Gunter in the 16th
century. Using the slide rule, one could perform operations like addition, subtraction,
multiplication and division. It was used extensively till late 1970s. Figure 1.2 shows a
slide rule.
, Figure 1.2 Slide rule
Pascal’s Adding and Subtraction Machine was developed by Blaise Pascal. It could add
and subtract. The machine consisted of wheels, gears and cylinders.
Leibniz’s Multiplication and Dividing Machine was a mechanical device that could both
multiply and divide. The German philosopher and mathematician Gottfried Leibniz built
it around 1673.
Punch Card System was developed by Jacquard to control the power loom in 1801. He
invented the punched card reader that could recognize the presence of hole in the
punched card as binary one and the absence of the hole as binary zero. The Os and 1s are
the basis of the modern digital computer. A punched card is shown in Figure 1.3.
Figure 1.3 Punched card
Babbage’s Analytical Engine An English man Charles Babbage built a mechanical
machine to do complex mathematical calculations, in the year 1823. The machine was
called as difference engine. Later, Charles Babbage and Lady Ada Lovelace developed a
general-purpose calculating machine, the analytical engine. Charles Babbage is also
called the father of computer.
Hollerith’s Punched Card Tabulating Machine was invented by Herman Hollerith. The
machine could read the information from a punched card and process it electronically.
The developments discussed above and several others not discussed here, resulted in the
development of the first computer in the 1940s.
1.5 GENERATIONS OF COMPUTER
INTRODUCTION TO COMPUTER
Contents
Digital and analog computers
Characteristics of computer—Speed, accuracy, diligence, storage capability, versatility
History of computer—Calculating machines, Napier’s bones, slide rule, Pascal's adding
and subtraction machine, Leibniz's multiplication and dividing machine, punch card
system, Babbage's analytical engine, Hollerith's punched card tabulating machine
Generations of computer
o First generation (1940 to 1956): Using vacuum tubes
o Second generation (1956 to 1963): Using transistors
o Third generation (1964 to 1971): Using integrated circuits
o Fourth generation (1971 to present): Using microprocessors
o Fifth generation (present and next): Using artificial intelligence
Classification of computer—Microcomputers (desktop computer or Personal Computer
(PC), notebook computers or laptop, netbook, tablet computer, handheld computer or
Personal Digital Assistant (PDA), smart phones), minicomputers, mainframe computers,
supercomputers )
The computer system—Hardware, software, data, users
The Input-process-output concept
Components of computer hardware—Input/output unit, central processing unit, storage
unit
Application of computers—Education, entertainment, sports, advertising, medicine,
science and engineering, government, home
Why this chapter
Computers are an integral part of our lives. Wherever we are—sitting in our homes, working in
the office, driving on roads, sitting in a movie hall, staying in a hotel, etc.—our lives are directly
or indirectly affected by the computers. In this era of information, we are dependent on the
storage, flow and processing of data and information, which can only be possible with the help of
computers. The purpose of this chapter is to introduce you to the “computer”.
1.1 INTRODUCTION
Nowadays, computers are an integral part of our lives. They are used for the reservation of
tickets for airplanes and railways, payment of telephone and electricity bills, deposit and
withdrawal of money from banks, processing of business data, forecasting of weather conditions,
diagnosis of diseases, searching for information on the Internet, etc. Computers are also used
,extensively in schools, universities, organizations, music industry, movie industry, scientific
research, law firms, fashion industry, etc.
The term computer is derived from the word compute. The word compute means to calculate. A
computer is an electronic machine that accepts data from the user, processes the data by
performing calculations and operations on it, and generates the desired output results. Computer
performs both simple and complex operations, with speed and accuracy.
This chapter discusses the history and evolution of computer, the concept of input-process-output
and the characteristics of computer. This chapter also discusses the classification of digital
computers based on their size and type, and the application of computer in different domain
areas.
1.2 DIGITAL AND ANALOG COMPUTERS
A digital computer uses distinct values to represent the data internally. All information are
represented using the digits Os and 1s. The computers that we use at our homes and offices are
digital computers.
Analog computer is another kind of a computer that represents data as variable across a
continuous range of values. The earliest computers were analog computers. Analog computers
are used for measuring of parameters that vary continuously in real time, such as temperature,
pressure and voltage. Analog computers may be more flexible but generally less precise than
digital computers. Slide rule is an example of an analog computer.
This book deals only with the digital computer and uses the term computer for them.
1.3 CHARACTERISTICS OF COMPUTER
Speed, accuracy, diligence, storage capability and versatility are some of the key characteristics
of a computer. A brief overview of these characteristics are—
Speed The computer can process data very fast, at the rate of millions of instructions per
second. Some calculations that would have taken hours and days to complete otherwise,
can be completed in a few seconds using the computer. For example, calculation and
generation of salary slips of thousands of employees of an organization, weather
forecasting that requires analysis of a large amount of data related to temperature,
pressure and humidity of various places, etc.
Accuracy Computer provides a high degree of accuracy. For example, the computer can
accurately give the result of division of any two numbers up to 10 decimal places.
Diligence When used for a longer period of time, the computer does not get tired or
fatigued. It can perform long and complex calculations with the same speed and accuracy
from the start till the end.
Storage Capability Large volumes of data and information can be stored in the computer
and also retrieved whenever required. A limited amount of data can be stored,
temporarily, in the primary memory. Secondary storage devices like floppy disk and
compact disk can store a large amount of data permanently.
, Versatility Computer is versatile in nature. It can perform different types of tasks with the
same ease. At one moment you can use the computer to prepare a letter document and in
the next moment you may play music or print a document.
Computers have several limitations too. Computer can only perform tasks that it has been
programmed to do. Computer cannot do any work without instructions from the user. It executes
instructions as specified by the user and does not take its own decisions.
1.4 HISTORY OF COMPUTER
Until the development of the first generation computers based on vacuum tubes, there had been
several developments in the computing technology related to the mechanical computing devices.
The key developments that took place till the first computer was developed are as follows—
Calculating Machines ABACUS was the first mechanical calculating device for
counting of large numbers. The word ABACUS means calculating board. It consists of
bars in horizontal positions on which sets of beads are inserted. The horizontal bars have
10 beads each, representing units, tens, hundreds, etc. An abacus is shown in Figure 1.1
Figure 1.1 Abacus
Napier’s Bones was a mechanical device built for the purpose of multiplication in 1617
ad. by an English mathematician John Napier.
Slide Rule was developed by an English mathematician Edmund Gunter in the 16th
century. Using the slide rule, one could perform operations like addition, subtraction,
multiplication and division. It was used extensively till late 1970s. Figure 1.2 shows a
slide rule.
, Figure 1.2 Slide rule
Pascal’s Adding and Subtraction Machine was developed by Blaise Pascal. It could add
and subtract. The machine consisted of wheels, gears and cylinders.
Leibniz’s Multiplication and Dividing Machine was a mechanical device that could both
multiply and divide. The German philosopher and mathematician Gottfried Leibniz built
it around 1673.
Punch Card System was developed by Jacquard to control the power loom in 1801. He
invented the punched card reader that could recognize the presence of hole in the
punched card as binary one and the absence of the hole as binary zero. The Os and 1s are
the basis of the modern digital computer. A punched card is shown in Figure 1.3.
Figure 1.3 Punched card
Babbage’s Analytical Engine An English man Charles Babbage built a mechanical
machine to do complex mathematical calculations, in the year 1823. The machine was
called as difference engine. Later, Charles Babbage and Lady Ada Lovelace developed a
general-purpose calculating machine, the analytical engine. Charles Babbage is also
called the father of computer.
Hollerith’s Punched Card Tabulating Machine was invented by Herman Hollerith. The
machine could read the information from a punched card and process it electronically.
The developments discussed above and several others not discussed here, resulted in the
development of the first computer in the 1940s.
1.5 GENERATIONS OF COMPUTER
