The document summarizes the five generations of computers from the first to fifth generation. The first generation used vacuum tubes and were large, unreliable, and expensive. The second generation used transistors, were smaller and more reliable. The third generation used integrated circuits, were faster and introduced keyboards/monitors. The fourth generation used microprocessors and were powerful yet small. The fifth generation has artificial intelligence capabilities.

2. Generations Of Computer
Introduction
 Modern computers are identified by their generations.
The term ‘ generation’ refers to the classification of
computer systems according to their technological
advancement specially a processing devices. The
efficiency of each generations has increased with
reduction in size and cost. Each new generation has
introduced some new applications. Since the birth of
first digital computer , history development of
electronic computers from 1945 onwards can be
divided into five generations.

3. First Generation Computer
(1946-1958)
 The computers are produced and used
between1946 to 1958 are called first generations
computers. The first generation computers were
marked by the use of vacuum tubes or valves as
their chief component. The first generation
computers were large in size and unreliable. They
required regular maintenance due to poor
technology.

4. Some features of the first
generations of computer are:
 Thousands of vacuum tubes were used which produced a
large amount of heat and burnt out frequently. Hence the
rooms / areas in which those computers were placed, had
to be properly air conditioned.
 They were very big in size, unreliable and slower than other
generations computers.
 Operating system was measured in terms of millisecond.
 Machine language was used to program them.
 Their cost was very high and they were not available for
commercial use.

5. Second Generation Computer
(1959-1964)
 The computers produced and used between
1959 and 1964 are called the second
generation computer .The second
generation computers were marked by the
use of transistors instead of vacuum tubes
.They were smaller in size and generated less
heat than the first generation computers .

6. Some features of the second
generation computers are:
•Transistors were used as a memory device.
•They were smaller in size than the first generation
because 1000 vacuum tubes were replaced by one
transistor.
•Processing speed was measured in microsecond.
•Heat and power consumption was lesser than the first
generation computers.
•Assembly language was used to program these
computers.
Some of the examples of the second generation
computers were IBM 1401, Hewlet Packard 150II, IBM
1410, IBM 1420 etc.

7. Third Generation computers
(1965-1974)
 The computers produced and used between 1965 and
1974 are called the third generation computers .The
third generation computers were marked by the use of
IC [Integrated Circuit] instead of a transistor .They
were smaller in size ,faster and more reliable than the
second generation computers.

8. Some features of the third
generation computers are:
 Integrated circuits (IC) were used as a memory device.
 They were smaller in size and more reliable. They generated
less heat and consumed less power as compared to the
previous generation computers.
 Processing speed increased to nanosecond.
 They started to use a high level language.
 Keyboards and monitors were introduced for the first time.
Magnetic disks were used as secondary storage devices.

 Some of the examples of the third generation computers
were IBM 360, UNIVAC 1108 and HP 2100.

9. Fourth Generation Computers
(1975-1990):
 The computer produced between 1975 to 1990 are
called the fourth generation of computer. The fourth
generations computer were marked by the use of
VLSAC (Very Large Scaled Integrated circuits)
technology. In this generation, computers succeeded
to integrate Arithmetic logic unit (ALU) control unit
(CU) and memory unit on a single chip, which is
called microprocessor. As a result, computer became
more powerful in capacity but smaller in size.

10. The features of the fourth
generations of computer are:
 Microprocessor is the main component of the fourth
generation computer.
 Highly accurate and totally reliable
 Operating speed increased beyond picoseconds and MIPS
(millions of instruction per second)
 Massive use of magnetic and optical storage device with
capacity more than 100GB
 The smallest computer called micro, laptop, notebook,
palmtop and even smaller computer are being developed
 Use of advanced software and high level language(4th
generation languages(4GL)
 Some of the examples of the fourth generation computer are
apple ll, IBM 80286, IBM 80386,IBM 80486 e.t.c

11. Fifth Generation Computer
(1991 onwards):
 The first microprocessor, Intel 4004 was 4 bits
microprocessor. The major shortcoming in the earlier
generation was lack of thinking power .The fifth
generation computer system project was initiated by
Japan’s Ministry of International Trade and Industry in
1982 .The fifth generation computers have artificial
intelligence [AI] . AI refers to the human behaviors put
in the computer.

12. Some features of the fifth
generation computers are:
 These computers use Ultra Large Scale Integrated
(ULSIC) circuits.
 A number of CPUs are added for better performance.
 Computers have artificial intelligence (AL).
 Large subsets of natural languages (like English,
German, and Japanese) are used and they are made
more user-friendly.
 PROLOG (Programming Logic) and Mercury are used as
the fifth generation programming languages.