Computer Science | Class 9th | Written by: Habib Rehman Janwiri

Computer Science

1.1 INTRODUCTION TO COMPUTER

A computer is an electronic data processing machine or device that
performs processes, calculations and operations based on instructions
provided by a program. Computers are now used vastly in every field of life.
The advancement in computer caused advancement in knowledge, science
and technology. Today, computers are used in fields of business, industry,
education, banking, transportation, research, explorations, media,
entertainment , etc.
1.1.1 Evolution Of Computers
The computers which we see today are modern shape of computers
which have been evolved since centuries. The evolution of computers is
generally divided in following three eras.
(i) Mechanical Era (Dark Age)
Men have been trying to invent machines that can solve
mathematical problems. In mechanical era, human became successful to
make simple machines that could help performing simple arithmetic
operation, in other words computing. These machines were manually
operated since the electricity was not invented. Some of the important
machines of this era are:
(a) Abacus (3000 B.C.)
Abacus was invented about 5000 years ago. It is
also known as counting frame. Abacus is still used to
teach basic arithmetic operations to the students.
Abacus is considered as first computer prototype.
(b) Napier's Bones (1612 A.D.)
Scottish mathematician John Napier
developed Napier's Bones, in 1612.It is also called
Napier's Rods. It was a small machine that contained
ten rods. The rods were made up of bones, wood or
metal. Napier's Bones was used for multiplication
and division.
(c) Slide Rule (1622 A.D.)
English mathematician William
Oughtred invented a Slide Rule. This was
basically a pair of two moveable rules
placed side by side. They had a
standardized set of markings called
scales. These scales were used for
mathematical computations. Slide Rule
was used to multiply and divide numbers.
The modern slide rules are still used in
some countries.
(d) Pascaline or Pascal's Calculator (1642 A.D.)
French mathematician Blaise Pascal
invented a mechanical calculator which was
called Pascaline. He developed this machine
to help his father who was a tax collector.
Pascaline can perform addition and
subtraction by eight figures. User had to
adjust wheels in order to perform these
calculations.
(e) Leibniz's Calculator (1694 A.D.)
Leibniz's Calculator was developed by
the German mathematician Gottfried
Wilhelm Leibniz. It was also called stepped
reckoner. It was the first calculator that
could perform all four basic arithmetic
operations; addition, subtraction, multiplication and division.
Ÿ Demonstrate the understanding about the history of
computers
Ÿ Outline the various generations of computers
Ÿ Classify the computers as per their size and
technology used to date
SLOs
) Napier's Bones (1612 A.D.)
Scottish mathematician John Napier
developed Napier's Bones, in 1612.It is also called
Napier's Rods. It was a small machine that contained
ten rods. The rods were made up of bones, wood or
metal. Napier's Bones was used for multiplication
and division.
(c) Slide Rule (1622 A.D.)
English mathematician William
Oughtred invented a Slide Rule. This was
basically a pair of two moveable rules
placed side by side. They had a
standardized set of markings called
scales. These scales were used for
mathematical computations. Slide Rule
was used to multiply and divide numbers.
The modern slide rules are still used in
some countries.
(d) Pascaline or Pascal's Calculator (1642 A.D.)
French mathematician Blaise Pascal
invented a mechanical calculator which was
called Pascaline. He developed this machine
to help his father who was a tax collector.
Pascaline can perform addition and
subtraction by eight figures. User had to
adjust wheels in order to perform these
calculations.
(e) Leibniz's Calculator (1694 A.D.)
Leibniz's Calculator was developed by
the German mathematician Gottfried
Wilhelm Leibniz. It was also called stepped
reckoner. It was the first calculator that
could perform all four basic arithmetic
operations; addition, subtraction, multiplication and division.
Babbage's Difference and Analytical Engines
(1822 and 1837 A.D.)
Charles Babbage was an English mathematician and mechanical
engineer. He is known as Father of Computer because he developed the
first complete computing machine. His first invention was Difference
Engine. It was an automatic mechanical calculator. Difference Engine
was a large machine, made of metal and was powered by steam. The
Difference Engine had storage (mechanical memory) that could hold the
data temporarily for processing and to store results. It was used to allow a
user to enter calculations and get printed results. The Difference Engine
worked on difference equations.
Then, Charles Babbage designed but could not build a very big machine in
1837. This was named Analytical Engine. The proposed design included
an ALU with basic programmatic flow control. It was programmed using
punched cards and contained integrated memory. Historians consider it
to be the first design concept of a general-purpose computer because of its
comprehensive design.
(ii) Electro-Mechanical Era (Middle Age)
th This era starts from the mid of 19 century. In this era scientists
became able to develop faster and more accurate computing machines as
they were powered by steam and electricity. One of such machines was
Tabulating Machine.
(a) Herman Hollerith's Tabulating Machine (1890 A.D.)
It was invented by American inventor
Herman Hollerith in 1890.Hollerith's first
tabulator was used for the U.S. 1890
Census. Because of Hollerith's tabulating
machine census data took only six months to
compile, which was very fast as compared to
previous U.S. census in 1880 which took 7
years to be completed. Hollerith Tabulating
Machine became very famous and used in
many offices of U.S. Government.
(iii) Electronic Era (Modern Age)
The advancement in the vacuum or electron tube gave birth to the
electronic era. In this era the true computers were invented which worked
on the principle of input, store, process and output. Continuous
advancement in electronic engineering increased efficiency and speed of
computers considerably. The electronic era may be categorized in
generations on the basis of core technology used to build computers.
(a) First Generation of Computers (1940 to1956)
Based on vacuum tubes, first
generation computers were very
Herman Hollerith's Tabulating Machine (1890 A.D.)
It was invented by American inventor
Herman Hollerith in 1890.Hollerith's first
tabulator was used for the U.S. 1890
Census. Because of Hollerith's tabulating
machine census data took only six months to
compile, which was very fast as compared to
previous U.S. census in 1880 which took 7
years to be completed. Hollerith Tabulating
Machine became very famous and used in
many offices of U.S. Government.
(iii) Electronic Era (Modern Age)
The advancement in the vacuum or electron tube gave birth to the
electronic era. In this era the true computers were invented which worked
on the principle of input, store, process and output. Continuous
advancement in electronic engineering increased efficiency and speed of
computers considerably. The electronic era may be categorized in
generations on the basis of core technology used to build computers.
(a) First Generation of Computers (1940 to1956)
Based on vacuum tubes, first
generation computers were very
large in size. This generation
computers used machine language
(i.e. 1's and 0's).Magnetic drums
were used as primary internal
storage medium and punched cards
for input. In this generation mainly
batch processing operating system
was used. Computers of this
generation were primarily used for
scientific and research purposes.
Electronic Numerical Integrator and
Calculator (ENIAC), Universal
Automatic Computer (UNIVAC) are
examples of fi rst generation
computers.
(b) Second Generation of Computers (1956 to 1963)
Because of transistors computers
became smaller, faster, cheaper and more
efficient. Assembly language and a high-level
language FORTRAN were introduced. Magnetic
core was used as primary internal storage
medium. Punched Cards were used for input.
Batch processing and Multiprogramming
Operating systems were used. These computers
were mainly used for commercial productions,
scientific and engineering analysis and design.
Examples are IBM 7094 and IBM 1401.
(c) Third Generation of Computers (1964 to 1971)
Use of ICs further decreased size
of computers and increased the speed
and e ffi c i enc y . Le s s e xpens i v e
computers were introduced. High level
programming languages such as Pascal
and COBOL were used. Keyboard as
input and monitor as output also eased
the use of computer. Time-sharing and
Realtime Operating Systems were used.
The use of computers was extended to
database management and automatic industrial control. IBM 360 and
IBM 370 are the examples of this generation's computers.
(d) Fourth Generation of Computers (1971 to Present)
The invention of microprocessors was
revolutionary which caused the development of
faster, less expensive, smaller and more
reliable computers. They used semi-conductor
memories RAM and ROM and magnetic storage
became popular. More high-level languages
were introduced like C, C++, Java, etc. These
computers are used in almost every field of life,
like space applications, business and art work.
Time sharing, real time and distributed operating system are used. This
generation also saw the development of Graphical User Interfaces (GUIs).
Examples are Apple Macintosh, IBM PC.
(e) Fifth Generation of Computers (Present and Beyond)
Fifth Generation computing
devices are still being developed.
In this generation computers will
be capable of self- learning,
reasoning and generalization.
These computers or controlled
machines like robot will also be
able to process human languages.
The branches of AI include;
Machine Learning, Deep Learning.
Natural Language Processing,
Robotics and Expert Systems.
1.1.2 Classification Of Computers
Computers can be classified into different ways as shown below:
Special
Purpose
General
Purpose
Micro
Computer
Mini
Computer
Mainframe
Computer
Super
Computer
Hybrid
Digital
Analog
Technology/ Type of
Data Handled Size Purpose
Classification of Computers