1. Define computer.
Ans: A ‘computer’ is an electronic machine used for performing calculations and controlling
operations that can be expressed either in logical or numerical terms. In simple words, it is an electronic
device that performs diverse operations with the help of instructions needed to process the information
in order to achieve desired results. Using this versatile machine, millions of complex calculations can
be done in a mere fraction of time and difficult decisions can be made with more accuracy at low cost.
Although the application domain of a computer depends totally on human creativity and imagination,
it covers a huge area of applications including education, industries, government, medicine, scientific
research, law and music and arts.
2. State the characteristics of a computer in detail.
(or)
Explain the features of computer available for individuals and organizations.
Ans: Today, much of the world’s infrastructure depends on computers and it has profoundly changed
our lives, mostly for better. Some of the characteristics of the computers that make them an essential part
of every emerging technology and a desirable tool in the human development are as follows:
• Speed: Computers process data at an extremely fast rate – millions of instructions per second.
In few seconds, a computer can perform a huge task that a normal human being may take days or
even years to complete. The speed of a computer is calculated in MHz (Megahertz), that is, one
million instructions per second. At present, a powerful computer can perform billions of operations
in just one second.
• Accuracy: Besides efficiency, computers are accurate as well. The level of accuracy depends on
the instructions and the type of machine being used. Since computer is capable of doing only
what it is instructed to do, faulty instructions for data processing may lead to faulty results. This is
known as GIGO (Garbage In Garbage Out).
1
Fundamentals
of Computers
M01_ITL-ESL4791_01_SE_C01.indd 3 12/22/2012 4:52:20 PM
I-4 Computer Fundamentals
• Diligence: Computer, being a machine, does not suffer from the human traits of tiredness and lack
of concentration. If four million calculations have to be performed, then the computer will perform
the last four-millionth calculation with the same accuracy and speed as the first calculation.
• Reliability: Generally, reliability is the measurement of performance of a computer, which is mea-
sured against some predetermined standard for operation without any failure. The major reason
behind the reliability of the computers is that, at hardware level, it does not require any human
intervention between its processing operations. Moreover, computers have built-in diagnostic
capabilities, which help in continuous monitoring of the system.
• Storage capability: Computers can store large amounts of data and can recall the required infor-
mation almost instantaneously. The main memory of the computer is relatively small and it can
hold only a certain amount of information, therefore, the data is stored on secondary storage
devices such as magnetic tape or disks. Small sections of the data can be accessed very quickly
and brought into the storage devices, as and when required, for processing.
• Versatility: Computers are quite versatile in nature. They can perform multiple tasks simultane-
ously with great ease. For example, at one moment it can be used to draft a letter, another moment
it can be used to play music and in between, one can print a document as well. All this work is
possible by changing the program (computer instructions).
• Resource sharing: In the initial stages of development, computers used to be isolated machines.
With the tremendous growth in computer technologies, computers today have the capability to
connect with each other. This has made the sharing of costly resources such as printers possible.
Apart from device sharing, data and information can also be shared among groups of computers,
thus creating a large information and knowledge base.
3. Explain in detail about the evolution of computers.
Ans: The need for a device to do calculations along with the growth in commerce and other human
activities explain the evolution of computers. Computers were preceded by many devices which man-
kind developed for their computing requirements. However, many centuries elapsed before technology
was adequately advanced to develop computers. Some of the ancient time devices which led to evolution
of computers are as follows:
Sand Tables
In ancient times, people used fingers to perform the calculations such as addition and subtraction. Even
today, simple calculations are done on fingers. Soon, mankind realized that it would be easier to do cal-
culations with pebbles as compared to fingers. Consequently, pebbles were used to represent numbers,
which led to the development of sand tables. They are known to be the earliest device for computa-
tion. A sand table consists of three grooves in the sand with a maximum of 10 pebbles in each groove.
To increase the count by one, a pebble has to be added in the right-hand groove. When 10 pebbles were
collected in the right groove, they were removed and one pebble was added to the adjacent left groove.
Abacus
Abacus is a counting device devised by the people in Asia Minor to simplify the process of counting. The
word ‘abacus’ was derived from Arabic word ‘abaq’ which means ‘dust’. An abacus consists of sliding
beads arranges on a rack, which has two parts, namely, upper and lower. The upper part contains two
beads and the lower part contains five beads per wire. The numbers are represented by the position of the
beads on the rack. For example, in the upper part of the rack, a raised bead denotes 0 whereas a lowered
M01_ITL-ESL4791_01_SE_C01.indd 4 12/22/2012 4:52:20 PM
Fundamentals of Computers I-5
bead denotes digit 5. In the lower part, a raised bead stands for 1 and a lowered bead for 0. The arithmetic
operations such as addition and subtraction can be performed by positioning the beads appropriately.
Napier Bones
In 1614, a Scottish mathematician, John Napier made a more sophisticated computing machine called
‘Napier bones’. This was a small instrument made up of 10 rods, on which the multiplication table
was engraved. It was made up of the strips of ivory bones, and so the name Napier bones. This device
enabled the multiplication in a fast manner, if one of the numbers was of one digit only (e.g., 6 × 6,745).
Incidentally, Napier also played a key role in the development of logarithms, which stimulated the inven-
tion of slide rule, which substituted the addition of logarithms for multiplication. This was a remarkable
invention as it enabled to perform the multiplication and division operations by converting them into
simple addition and subtraction.
Slide Rule
The invention of logarithms influenced the development of another famous invention known as ‘slide
rule’. In AD 1620, the first slide rule came into existence. It was jointly devised by two British mathema-
ticians, Edmund Gunter and William Oughtred. It was based on the principle that the actual distances
from the starting point of the rule are directly proportional to the logarithm of the numbers printed
on the rule. The slide rule is embodied by two sets of scales that are joined together, with a marginal
space between them. This space is enough for the free movement of the slide in the groove of the rule.
The suitable alliance of two scales enabled the slide rule to perform multiplication and division by a
method of addition and subtraction.
Pascaline
In 1623, Wilhelm Schickard invented the calculating clock, which could add and subtract, and indi-
cated the overflow by ringing a bell. Subsequently, it helped in the evolution of Pascaline. In AD 1642,
French mathematician, scientist and philosopher, Blaise Pascal invented the first functional automatic
calculator. It had a complex arrangement of wheels, gears and windows for displaying numbers. It was
operated by a series of dials attached to wheels with each wheel having ten segments (numbered from
zero to nine) on its circumference. When a wheel made a complete turn, the wheel on its left advanced
by one segment. Indicators above the dial displayed the correct answer. However, usage of this device
was limited to addition and subtraction only.
Analytical Engine
Analytical engine is considered to be the first general-purpose programmable computer. Babbage’s
innovation in the design of the analytical engine made it possible to test the sign of a computed number
and take one course of action if the sign was positive and another if the sign was negative. Babbage
also designed this device to advance or reverse the flow of punched cards to permit branching to any
desired instruction within a program. Lady Ada Lovelace helped Babbage in the development of the
analytical engine. She wrote articles and programs for the proposed machine. Due to her contributions,
she is known as the first programmer. However, Babbage never completed the analytical engine, but his
proposal for this device reviewed the basic elements of modern computer such as input/output, storage,
processor and control unit.
M01_ITL-ESL4791_01_SE_C01.indd 5 12/22/2012 4:52:20 PM
I-6 Computer Fundamentals
Hollerith’s Tabulator
Herman Hollerith invented the punched-card tabulating machine to process the data collected in the
United States’ census. This electronic machine was able to read the information on the cards and pro-
cess it electronically. It consisted of a tabulator, a sorter with compartments electronically controlled
by the tabulator‘s counter and the device used to punch data onto cards. This tabulator could read the
presence or absence of holes in the cards by using spring-mounted nails that passed through the holes to
make electrical connections. In 1896, Hollerith founded the Tabulating Machine Company, which was
later named as International Business Machines (IBM).
4. Explain about the generations of computers.
Ans: The history of computer development is often discussed with reference to the different gen-
erations of computing devices. In computer terminology, the word ‘generation’ is described as a stage
of technological development or innovation. A major technological development that fundamentally
changed the way the computers operate, resulting in increasingly smaller, cheaper and more powerful
and more efficient and reliable devices characterize each generation of computer. According to the type
of processor installed in a machine, there are five generations of computers which are as follows:
First Generation (1940–1956): Vacuum Tubes
First generation computers were vacuum tubes/thermionic valves-based machines. These computers
used vacuum tubes for circuitry and magnetic drums for memory. A ‘magnetic drum’ is a metal cylin-
der coated with magnetic iron-oxide material on which data and programs can be stored. The input was
based on punched cards and paper tape and the output was in the form of printouts.
First generation computers relied on binary-coded language also called ‘machine language’ (lan-
guage of 0s and 1s) to perform operations and were able to solve only one problem at a time. These
were the fastest computing devices of their times (computation time was in milliseconds). However,
each machine was fed with different binary codes and were difficult to program. This resulted in lack
of versatility and speed. Moreover, since thousands of vacuum tubes were used, they generated a large
amount of heat. Therefore, air conditioning was essential. In addition, to run on different types of com-
puters, instructions must be rewritten or recompiled. Some examples of first generation computers are
ENIAC, EDVAC and UNIVAC.
Second Generation (1956–1963): Transistors
Second generation computers used transistors, which were superior to vacuum tubes. A ‘transistor’
is made up of semiconductor material such as germanium and silicon. It usually has three leads and
performs electrical functions such as voltage, current or power amplification with low power require-
ments. Since transistor is a small device, the physical size of computers was greatly reduced. Computers
became smaller, faster, cheaper, energy-efficient and more reliable than their predecessors. In second
generation computers, magnetic cores were used as primary memory and magnetic disks as secondary
storage devices. However, they still relied on punched cards for input and printouts for output.
One of the major developments of this generation includes the progress from machine language
to assembly language. Assembly language uses mnemonics (abbreviations) for instructions rather
than numbers, for example, ADD for addition and MULT for multiplication. As a result, program-
ming became less cumbersome. These computers were more reliable and less prone to hardware failure,
hence, they required less frequent maintenance. Moreover, these were more portable and generated less
M01_ITL-ESL4791_01_SE_C01.indd 6 12/22/2012 4:52:20 PM
Fundamentals of Computers I-7
amount of heat. However, the second generation computers still required air conditioning and manual
assembly of individual components into a functioning unit. Some examples of second generation com-
puters are
PDP-8, IBM 1401 and IBM 7090.
Third Generation (1964–early 1970s): Integrated Circuits
The development of the integrated circuit was the trait of the third generation computers. An ‘integrated
circuit’ (also called an ‘IC’) consists of a single chip (usually silicon) with many components such as
transistors and resistors fabricated on it. Integrated circuits replaced several individually wired transistors.
This development made computers smaller in size, reliable and efficient.
Instead of punched cards and printouts, users interacted with third generation computers through
keyboards and monitors and interfaced with operating system. This allowed the device to run many
different applications simultaneously with a central program that monitored the memory. For the first
time, computers became accessible to mass audience because they were smaller and cheaper than
their predecessors. The main advantage of these computers was that manual assembling of individual
components was not required, so it reduced the large requirement of labour and cost. However, highly
sophisticated technologies were required for the manufacturing of IC chips. Some examples of third
generation computers are NCR 395 and B6500.
Fourth Generation (Early 1970s–till date): Microprocessors
The fourth generation is an extension of third generation technology. Although, the technology of this
generation is still based on the integrated circuit, these have been made readily available to us because of
the development of the microprocessor (circuits containing millions of transistors). The Intel 4004 chip,
which was developed in 1971, took the IC one step further by locating all the components of a computer
(central processing unit, memory and input and output controls) on a miniscule chip. A microprocessor
is built onto a single piece of silicon, known as ‘chip’. It is about 0.5 cm along one side and no more
than 0.05 cm thick.
The fourth generation computers led to an era of Large-Scale Integration (LSI) and Very-Large-Scale
Integration (VLSI) technology. LSI technology allowed thousands of transistors to be constructed on
one small slice of silicon material, whereas VLSI squeezed hundreds of thousands of components on
to a single chip. Ultra-large-scale integration (ULSI) increased that number into millions. This way,
computers became smaller and cheaper than even before.
The fourth generation computers became more powerful, compact, reliable and affordable. As a result,
it gave rise to the personal computer (PC) revolution. During this period, magnetic core memories were
substituted by semiconductor memories that resulted in faster random access main memories. Moreover,
secondary memories such as hard disks became economical, smaller and bigger in capacity. The other
significant development of this era was that these computers could be linked together to form networks,
which eventually led to the development of the Internet. This generation also saw the development of
the ‘Graphical User Interfaces (GUIs)’, mouse and hand-held devices. Despite many advantages, this
generation required complex and sophisticated technology for the manufacturing of CPU and the other
components. Some examples of fourth generation computers are Apple II, Altair 8800 and CRAY-1.
Fifth Generation (Present and beyond): Artificial Intelligence
The dream of creating a human-like computer that would be capable of reasoning and reaching at
a decision through a series of ‘what-if-then’ analyses have existed since the beginning of computer
M01_ITL-ESL4791_01_SE_C01.indd 7 12/22/2012 4:52:20 PM
..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.