1. SESSION 1 : HISTORY OF COMPUTERS
INTRODUCTION : As the twenty-first century usher in the Information
Age, we are experiencing new ways of living and working. The only way we can take
advantage of and manage the vast amounts of available information is through the
understanding of how computers work and through the ability to use computers. We all
believe that knowing how to use a computer is a basic skill necessary to succeed in the
work world and to function effectively in society.
OBJECTIVES :
• Define the word computer.
• Define the characteristics of computer
• Discuss the History of computers

2. 1.1 INTRODUCTION TO COMPUTER
Humans have always needed to perform arithmetic like counting and adding.
During the pre-historic period, they counted either on their fingers or by
scratching marks on the bones and then with the help of stone, pebble and beads.
The early civilization had witnessed men develop number systems to keep track
of the astronomical cycles, businesses, etc. The word 'computing' means 'an act of
calculating'. After the invention of the manual calculating tools, the concept of
using 'electronic gadgets' for computations were introduced which gave birth to
the computers.
Computer...All of us knows what it means today : A small metal box which
makes us able to surf on the net, play extremely life-like games, listen to music, or
watch movies. “A computer is a device that is capable to processing information
or data. The world’s greatest and most advanced computer is the human body.
Your mind is much faster and far superior to any computer in existence.” It can
be compared to a magic box, which serves different purpose to different people.
For a common man computer is simply a calculator, which works automatic and
quite fast. For a person who knows much about it, computer is a machine capable
of solving problems and manipulating data. It accepts data, processes the data by
doing some mathematical and logical operations and gives us the desired output.
Therefore, we may define computer as a device that transforms data. Data can be
anything like marks obtained by you in various subjects. It can also be name, age,
sex, weight, height, etc. of all the students in your class or income, savings,
investments, etc., of a country.
Computer can be defined in terms of its functions. It can accept data, store data,
process data as desired, retrieve the stored data as and when required print the
result in desired format.

3. 1.2 CHARACTERISTICS OF COMPUTER
The important characteristics of a computer are described below:
1. Speed
The computer is a very high speed electronic device. The operations on the data
inside the computer are performed through electronic circuits according to the
given instructions. The data and instructions flow along these circuits with high
speed that is close to the speed of light. Computer can perform million of billion
of operations on the data in one second. The computer generates signals during
the operation process therefore the speed of computer is usually measure in mega
hertz (MHz) or gega hertz (GHz). It means million cycles units of frequency is
hertz per second. Different computers have different speed.
2. Arithmetical and Logical Operations
A computer can perform arithmetical and logical operations. In arithmetic
operations, it performs the addition, subtraction, multiplication and division on
the numeric data. In logical operation it compares the numerical data as well as
alphabetical data.
3. Accuracy
In addition to being very fast, computer is also very accurate device. it gives
accurate output result provided that the correct input data and set of instructions
are given to the computer. It means that output is totally depended on the given
instructions and input data. If input data is in-correct then the resulting output will
be in-correct. In computer terminology it is known as garbage-in garbage-out.
4. Reliability

4. The electronic components in modern computer have very low failure rate. The
modern computer can perform very complicated calculations without creating any
problem and produces consistent (reliable) results. In general, computers are very
reliable. Many personal computers have never needed a service call.
Communications are also very reliable and generally available whenever needed.
5. Storage
A computer has internal storage (memory) as well as external or secondary
storage. In secondary storage, a large amount of data and programs (set of
instructions) can be stored for future use. The stored data and programs are
available any time for processing. Similarly information downloaded from the
internet can be saved on the storage media.
6. Retrieving data and programs
The data and program stored on the storage media can be retrieved very quickly
for further processing. It is also very important feature of a computer.
7. Automation
A computer can automatically perform operations without interfering the user
during the operations. It controls automatically different devices attached with the
computer. It executes automatically the program instructions one by one.
8. Versatility
Versatile means flexible. Modern computer can perform different kind of tasks
one by one of simultaneously. It is the most important feature of computer. At one
moment your are playing game on computer, the next moment you are composing
and sending emails etc. In colleges and universities computers are use to deliver
lectures to the students. The talent of computer is dependent on the software.

5. 9. Communications
Today computer is mostly used to exchange messages or data through computer
networks all over the world. For example the information can be received or send
throug the internet with the help of computer. It is most important feature of the
modern information technology.
10. Diligence
A computer can continually work for hours without creating any error. It does not
get tired while working after hours of work it performs the operations with the
same accuracy as well as speed as the first one.
11. No Feelings
Computer is an electronic machine. It has no feelings. It detects objects on the
basis of instructions given to it. Based on our feelings, taste, knowledge and
experience: we can make certain decisions and judgments in our daily life. On the
other hand, computer can not make such judgments on their own. Their judgments
are totally based on instructions given to them.
12. Consistency
People often have difficulty to repeat their instructions again and again. For
example, a lecturer feels difficulty to repeat a same lecture in a class room again
and again. Computer can repeat actions consistently (again and again) without
loosing its concentration:
• To run a spell checker (built into a word processor) for checking spellings
in a document.
• To play multimedia animations for training purposes.

6. • To deliver a lecture through computer in a class room etc.
A computer will carry out the activity with the same way every time. You can
listen a lecture or perform any action again and again.
13. Precision
Computers are not only fast and consistent but they also perform operations very
accurately and precisely. For example, in manual calculations and rounding
fractional values (That is value with decimal point can change the actual result).
In computer however, you can keep the accuracy and precision upto the level, you
desire. The length calculations remain always accurate.

7. 1.3 HISTORY OF COMPUTERS
The first computers were people! Electronic computers (and the earlier
mechanical computers) were given this name because they performed the work
that had previously been assigned to people. "Computer" was originally a job
title: it was used to describe those human beings (predominantly women) whose
job it was to perform the repetitive calculations required to compute such things
as navigational tables, tide charts, and planetary positions for astronomical
almanacs. Imagine you had a job where hour after hour, day after day, you were
to do nothing but compute multiplications. Boredom would quickly set in, leading
to carelessness, leading to mistakes. And even on your best days you wouldn't be
producing answers very fast. Therefore, inventors have been searching for
hundreds of years for a way to mechanize (that is, find a mechanism that can
perform) this task, One such device was the abacus.
The abacus was an early aid for mathematical computations. Its only value is that
it aids the memory of the human performing the calculation. A skilled abacus
operator can work on addition and subtraction problems at the speed of a person
equipped with a hand calculator (multiplication and division are slower). The
abacus is often wrongly attributed to
China. In fact, the oldest
surviving abacus was used in 300
B.C. by the Babylonians. The abacus
is still in use today, principally
in the far east. A modern
abacus consists of rings that slide
over rods, but the older one pictured below dates from the time when pebbles
were used for counting (the word "calculus" comes from the Latin word for
pebble).

8. 1.4 MECHANICAL DEVICES
1.4.1 PASCALINE
In 1642 Blaise Pascal, at age 19, invented the Pascaline as an aid for his father
who was a tax collector. Pascal built 50 of this gear-driven one-function
calculator (it could only add)
but couldn't sell many because
of their exorbitant cost and
because they really weren't that
accurate (at that time it was not
possible to fabricate gears with
the required precision). Up
until the present age when car dashboards went digital, the odometer portion of a
car's speedometer used the very same mechanism as the Pascaline to increment
the next wheel after each full revolution of the prior wheel. Pascal was a child
genius.
1.4.2 DIFFERENCE ENGINE
By 1822 the English
mathematician Charles Babbage
was proposing a steam driven
calculating machine the size of a
room, which he called the
Difference Engine. This
machine would be able to
compute tables of numbers, such
as logarithm tables. He obtained
government funding for this project due to the importance of numeric tables in
ocean navigation. By promoting their commercial and military navies, the British
government had managed to become the earth's greatest empire. But in that time

9. frame the British government was publishing a seven volume set of navigation
tables which came with a companion volume of corrections which showed that
the set had over 1000 numerical errors. It was hoped that Babbage's machine
could eliminate errors in these types of tables. But construction of Babbage's
Difference Engine proved exceedingly difficult and the project soon became the
most expensive government funded project up to that point in English history.
Ten years later the device was still nowhere near complete, acrimony abounded
between all involved, and funding dried up. The device was never finished
however the ideas for the Difference Engine led to the design of Babbage’s
Analytical Engine.
1.4.3 ANALYTIC ENGINE
Soon after the attempt at making the difference engine crumbled, Babbage started
designing a different, more complex machine called the Analytic Engine. This
device, large as a house and powered by 6 steam engines, would be more general
purpose in nature because it would be programmable, thanks to the punched card
technology of Jacquard. But it was Babbage who made an important intellectual
leap regarding the punched cards. In the Jacquard loom, the presence or absence
of each hole in the card physically allows a colored thread to pass or stops that
thread. Babbage saw that the pattern of holes could be used to represent an
abstract idea such as a problem statement or the
raw data required for that problem's solution.
Babbage saw that there was no requirement that
the problem matter itself physically pass thru
the holes.
Furthermore, Babbage realized that punched
paper could be employed as a storage mechanism, holding computed numbers for
future reference. Because of the connection to the Jacquard loom, Babbage called
the two main parts of his Analytic Engine the "Store" and the "Mill", as both

10. terms are used in the weaving industry. The Store was where numbers were held
and the Mill was where they were "woven" into new results. In a modern
computer these same parts are called the memory unit and the central processing
unit (CPU).
The Analytic Engine also had a key function that distinguishes computers from
calculators: the conditional statement. A conditional statement allows a program
to achieve different results each time it is run. Based on the conditional statement,
the path of the program (that is, what statements are executed next) can be
determined based upon a condition or situation that is detected at the very
moment the program is running.
1.5 ELECTRO-MECHANICAL DEVICES
1.5.1 Hollerith’s Tabulating Machine
By the end of the 19th century, U.S. Census officials were concerned about the
time it took to tabulate the continuously increasing number of Americans. This
counting was done every 10 years, as required by the Constitution. However, the
Census of 1880 took nine years to compile which made the figures out of date by
the time they were published. In response to a contest sponsored by the U.S.
Census Bureau, Herman Hollerith invented a tabulating machine that used
electricity rather than mechanical
gears. Holes representing
information to be tabulated were
punched in cards, with the
location of each hole
representing a specific piece of
information (male, female, age,
etc.). The cards were then
inserted into the machine and

11. metal pins used to open and close electrical circuits. If a circuit was closed, a
counter was increased by one.
This was the step towards automated computing, that could read the information
that had been punched into the cards automatically, without human help. Because
of this, reading errors were reduced dramatically, work flow increased, and, most
importantly, stacks of punched cards could be used as easily accessible memory
of almost unlimited size. Furthermore, different problems could be stored on
different stacks of cards and accessed when needed. These advantages were seen
by commercial companies and soon led to the development of improved punch-
card using computers created by International Business Machines (IBM).
1.5.2 MARK 1
Howard Aiken and Grace Hopper designed the MARK series of computers at
Harvard University. The MARK
series of computers began with the
Mark I in 1944. Imagine a giant
roomful of noisy, clicking metal
parts, 55 feet long and 8 feet high.
The 5-ton device contained almost 760,000 separate pieces. Used by the US Navy
for gunnery and ballistic calculations, the Mark I was in operation until 1959.
The computer, controlled by pre-punched paper tape, could carry out addition,
subtraction, multiplication, division and reference to previous results. It had
special subroutines for logarithms and trigonometric functions and used 23
decimal place numbers. Data was stored and counted mechanically using 3000
decimal storage wheels, 1400 rotary dial switches, and 500 miles of wire. Its
electromagnetic relays classified the machine as a relay computer. All output was
displayed on an electric typewriter. By today's standards, the Mark I was slow,
requiring 3-5 seconds for a multiplication operation.

12. SUMMARY :
Computer :
A computer is an electronic device that operates under the control of a set of instructions
that is stored in its memory unit. A computer accepts data from an input device and
processes it into useful information which it displays on its output device.
Characteristics:
• Speed
• Arithmetical and Logical Operations
• Accuracy
• Reliability
• Storage
• Retrieving data and programs
• Automation
• Versatility
• Communications
• Diligence
• No Feelings
• Consistency
• Precision
History of Computer:
The development of the modern day computer was the result of advances in technologies
and man's need to quantify. The abacus was one of the first counting machines..
Some of the earlier mechanical counting machines lacked the technology to make the
design work.
Mechanical Devices
• Blaise Pascal In 1642 invented Pascaline

13. • Charles Babbage “Father of computers” invented Difference Engine in 1822 and
Analytic Computer
Electro- Mechanical Devices
• Herman Hollerith invented a tabulating machine that used electricity rather than
mechanical gears called Hollerith’s Tabulating Machine
• Howard Aiken and Grace Hopper designed the MARK series of computers at
Harvard University.