The first electronic computer was designed and built at
the University of Pennsylvania based on vacuum tube
technology. Vacuum tubes were used to perform logic
operations and to store data.
Generations of computers has been divided into five
according to the development of technologies used to
fabricate the processors, memories and I/O units.
• A generation refers to the state of improvement
in the development of a product. This term is
also used in the different advancements of
computer technology. With each new
generation, the circuitry has gotten smaller and
more advanced than the previous generation
before it. As a result of
the miniaturization, speed, power,
and memory of computers has proportionally
increased. New discoveries are constantly being
developed that affect the way we live, work and
• I Generation : 1945 – 55
• II Generation : 1955 – 65
• III Generation : 1965 – 75
• IV Generation : 1975 – 89
• V Generation : 1989 to present
• VI Generation : Future
•During the period of 1940 to 1956 first generation of
computers were developed.
• The first generation computers used
vacuum tubes for circuitry and magnetic
drums for memory, and were often
enormous, taking up entire rooms.
• The vacuum tube was developed by
Lee De Forest. A vacuum tube is a device generally used to
amplify a signal by controlling the movement of electrons in
an evacuated space.
•First fully electronic digital
computer built in the U.S.
•Created at the University
•ENIAC weighed 30 tons
contained 18,000 vacuum
•Cost a paltry $487,000
(Universal Automatic Computer)
• First generation computers were based on vacuum
• The operating systems of the first generation
computers were very slow.
• They were very large in size.
• Production of the heat was in large amount in first
• Machine language was used for programming.
• First generation computers were unreliable.
• They were difficult to program and use.
It is the Bendix G-15 General Purpose Digital Computer,
a First Generation computer introduced in 1956.
The computers built in the 1950s and
1960s are considered the 2nd
generation computers. These
computers make use of the
transistors invented by Bell Telephone
laboratories and they had many of
the same components as the modern-
day computer. For instance, 2nd
generation computers typically had a
printer, some sort of tape or disk
storage, operating systems, stored
programs, as well as some sort of
memory. These computers were also
generally more reliable and were
solid in design.
A transistor computer is a computer which
uses discrete transistors instead
of vacuum tubes. The "first generation"
of electronic computers used vacuum
tubes, which generated large amounts of
heat, were bulky, and were unreliable. A
"second generation" of computers,
through the late 1950s and 1960s featured
boards filled with individual transistors
and . magnetic memory cores they were
first developed in 1947 They. Transistors
are most often used to regulate the flow
of an electrical current and to switch
electricity on and off.
Throughout the early 1960's, there were a number of commercially
successful second generation computers used in business, universities,
and government from companies such as Burroughs, Control Data,
Honeywell, IBM, Sperry-Rand, and others. These second generation
computers were also of solid state design, and contained transistors in
place of vacuum tubes. They also contained all the components we
associate with the modern day computer: printers, tape storage, disk
storage, memory, operating systems, and stored programs. By 1965,
most large business routinely processed financial information using
second generation computers.
It was the stored program and programming languages that gave
computers the flexibility to finally be cost effective and productive for
business use. The stored program concept meant that instructions to
run a computer for a specific function (known as a program) were held
inside the computer's memory, and could quickly be replaced by a
different set of instructions for a different function. A computer could
print customer invoices and minutes later design products or calculate
Main Characteristics of a second generation computer are..
Second generation computer machines were based on transistor technology.
Second generation computers were smaller as compared to the first generation
The computational time of Second generation computers was reduced to
microseconds from milliseconds.
Second generation computers were more reliable and less prone to hardware
failure. Hence, such computers required less frequent maintenance.
Second generation computers were more portable and generated less amount of
ssembly language was used to program Second generation computers. Hence,
programming became more time-efficient and less cumbersome.
Manual assembly of individual components into a functional unit was still required
3rd generation of computers
The 3rd Generation computers replaced
transistors with “integrated circuits” or I.C. was
inverted by Jack Kilby as Texas instruments in
The 3rd generation computers using integrated
circuits proved to be highly reliable, relatively
inexpensive, and faster. Less human labour is
required at assembly stage.
Example of some main frame computers
developed during this generation are-
ICL(International computer limited.)
CDA(Control Data Corporation.)
Fourth Generation (1971-Present)
• The microprocessor brought the fourth generation of
computers, as thousands of integrated circuits were
built onto a single silicon chip. What in the first
generation filled an entire room could now fit in the
palm of the hand. The Intel 4004 chip, developed in
1971, located all the components of the computer—
from the central processing unit and memory to
input/output controls—on a single chip.
Time Period: 1975 to Today
Technology: VLSI (Very Large Scale Integration)
Incorporated many millions of transistors &
electronic circuits on a single chip.
Size: Small as compared to first generation
Processing: Faster then first generation computer
• In 1981 IBM introduced its first computer for the
home user, and in 1984 Apple introduced the
Macintosh. Microprocessors also moved out of the
realm of desktop computers and become more
• As these small computers became more powerful,
they could be linked together to form networks,
which also led to the development of the Internet.
Fourth generation computers also saw the
development of the mouse and handheld devices.
FIFTH GENERATION COMPUTERS
• Fifth generation computing devices, based
on artificial intelligence, are still in development,
though there are some applications, such as voice
recognition, that are being used today. The use
of parallel processing and superconductors is
helping to make artificial intelligence a
reality. Quantum computation and molecular
and nanotechnology will radically change the face
of computers in years to come. The goal of fifth-
generation computing is to develop devices that
respond to natural language input and are
capable of learning and self-organization.
• Less power consumption .
• High performance, lower cost and very
• Computers based on artificial intelligence are
• Portable note book computers introduced .
• Memory chips up to 1 GB, hard disk drives up
to 180 GB and optical disks up to 27 GB are
available (still the capacity is increasing) .
• As a result of the various improvements to the
development of the computer we have seen the
computer being used in all areas of life. It is a
very useful tool that will continue to experience
new development as time passes.
• Computers are used in various areas of our life.
Education, entertainment, sports, advertising,
medicine, science and engineering, government,
office and home are some of the application
areas of the computers.