The document discusses the five generations of computers from the first generation that used vacuum tubes in 1942-1955 to the present fifth generation that uses artificial intelligence. It describes the defining technologies of each generation including vacuum tubes, transistors, integrated circuits, microprocessors, and artificial intelligence. It also outlines some of the advantages and disadvantages of the computers from each generation in terms of size, speed, reliability, cost and other factors.

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Generation of Computer
The development of electronic computer can be divided into generation depending upon the
technologies used. The generations of computers are as follow:
First Generation of Computers (1942-1955)
The beginning of commercial computer age is from UNIVAC (Universal Automatic Computer).
It was developed by two scientists MAUCHLY and ECHERT at the Census Department of United
States in 1947. The first generation computers were used during 1942-1955. They were based
on vacuum tubes. Examples of first generation computers are ENIVAC and UNIVAC-1 etc.
Advantages
 Vacuum tubes were the only electronic component available during those days.
 Vacuum tube technology made possible to make electronic digital computers.
 These computers could calculate data in millisecond.
Disadvantages
 The computers were very large in size.
 They consumed a large amount of energy.
 They heated very soon due to thousands of vacuum tubes.
 They were not very reliable.
 Air conditioning was required.
 Constant maintenance was required.
 Non-portable.
Generations of Computers
1st Generation (Vacuum tube) 1942-1955
2nd Generation (Transistor) 1955-1964
3rd Generation (Integrated Circuits) 1964-1975
4th Generation (Microprocessor) 1975-Present
5th Generation (Artificial intelligence) Present & Beyond

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 Costly commercial production.
 Limited commercial use.
 Very slow speed.
 Limited programming capabilities.
 Used machine language only.
 Used magnetic drums which provide very less data storage.
 Used punch cards for input.
 Not versatile and very faulty.
Second Generation Computers (1955-1964)
The second generation computers used transistors. The scientists at Bell Laboratories
developed transistor in 1947. These scientists include John Barden, William Brattain and William
Shockley. The size of the computers was decreased by replacing vacuum tubes with transistors. The
examples of second generation computers are IBM 7094 series, IBM 1400 series and CDC 164 etc.
Advantages
 Smaller in size as compared to the first generation computers.
 The 2nd generation Computers were more reliable
 Used less energy and were not heated.
 Wider commercial use
 Better portability as compared to the first generation computers.
 Better speed and could calculate data in microseconds
 Used faster peripherals like tape drives, magnetic disks, printer etc.
 Used Assembly language instead of Machine language.
 Accuracy improved.
Disadvantages
 Cooling system was required
 Constant maintenance was required
 Commercial production was difficult
 Only used for specific purposes
 Costly and not versatile
 Punch cards were used for input.

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Third Generation Computers (1964-1975)
The Third generation computers used the integrated circuits (IC). Jack Kilby developed the
concept of integrated circuit in 1958. It was an important invention in the computer field. The first IC
was invented and used in 1961. The size of an IC is about ¼ square inch. A single IC chip may contain
thousands of transistors. The computer became smaller in size, faster, more reliable and less expensive.
The examples of third generation computers are IBM 370, IBM System/360, UNIVAC
1108 and UNIVAC AC 9000 etc.
Advantages
 Smaller in size as compared to previous generations.
 More reliable.
 Used less energy
 Produced less heat as compared to the previous two generations of computers.
 Better speed and could calculate data in nanoseconds.
 Used fan for heat discharge to prevent damage.
 Maintenance cost was low because hardware failure is rare.
 Totally general purpose
 Could be used for high-level languages.
 Good storage
 Versatile to an extent
 Less expensive
 Better accuracy
 Commercial production increased.
 Used mouse and keyboard for input.
Disadvantages
 Air conditioning was required.
 Highly sophisticated technology required for the manufacturing of IC chips.
Fourth Generation Computers (1975-Present)
The fourth generation computers started with the invention of Microprocessor. The
Microprocessor contains thousands of ICs. Ted Hoff produced the first microprocessor in 1971

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for Intel. It was known as Intel 4004. The technology of integrated circuits improved rapidly. The LSI
(Large Scale Integration) circuit and VLSI (Very Large Scale Integration) circuit was designed. It
greatly reduced the size of computer. The size of modern Microprocessors is usually one square inch. It
can contain millions of electronic circuits. The examples of fourth generation computers are Apple
Macintosh & IBM PC.
Advantages
 More powerful and reliable than previous generations.
 Small in size
 Fast processing power with less power consumption
 Fan for heat discharging and thus to keep cold.
 No air conditioning required.
 Totally general purpose
 Commercial production
 Less need have repair.
 Cheapest among all generations
 All types of High level languages can be used in this type of computers
Disadvantages
 The latest technology is required for manufacturing of Microprocessors.
Fifth Generation Computers (Present & Beyond)
Scientists are working hard on the 5th generation computers with quite a few breakthroughs. It is
based on the technique of Artificial Intelligence (AI). Computers can understand spoken words &
imitate human reasoning. The ability to translate a foreign language is also moderately possible with
fifth generation computer.
Scientists are constantly working to increase the processing power of computers. They are trying
to create a computer with real IQ with the help of advanced programming and technologies. The
advancement in modern technologies will revolutionize the computer in future.

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Type of Computer
Computer can be divided into the following type on the basis of their working:
1. Analog Computer
An analog computer recognizes data as a continuous measurement of physical property.
Voltage, Pressure, Speed and temperature are some physical properties that can be measured in this way.
Its output is usually display on a meter or graph. It does not operate with digital signals. It has low
memory and fewer functions. It is difficult to operate and use. It is usually built for special purposes. It
is mainly used in engineering and medicine.
Examples
 Speedometer is used to measure the speed of car.
 Analog clock measure time by the distance traveled by hands of clock around a dial.
 Thermometer is an analog device that measures the length of mercury column
2. Digital computer
A digital computer processes data in numerical form using digital circuits. It performs arithmetic
and logic operations with discrete values. These values are 0 and 1. Everything is described in two ON
and OFF. The digit 1 represents ON and 0 represents OFF state. The digital computers are very fast.
These computers are manufactured in a variety of sizes, speeds and capacities. Digital computers are
commonly used at homes and in offices etc. Apple Macintosh and IBM PC are two important digital
computers.
Examples
 Digital watch display the time that does not vary continuously but changes from one discrete
value to the other.
Digital ComputerAnalog Computer Hybrid Computer
Compute
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 Digital scoreboard directly counts discrete values such as the time left to play and the score of
each team.
3. Hybrid Computers
A hybrid computer is a combination of both analog and digital computer. A hybrid computer
combines the best characteristics and digital computer. It can accept data in analog and digital form.
Examples
 Hybrid computer devices may calculate patient’s heart function, temperature, blood pressure etc.
This measurement can be converted and displayed in digital form.
Difference between Analog and Digital Computer
Analog Computer Digital Computers
1. It provides us continues value 1. It provides us discrete value
2. It represents physical quantities in the
form of waves or in a continuous form.
2. It represents physical quantities with
the help of symbols or numbers.
3. It has no states. 3. It has to states on (1) and of (0)
4. It is difficult to use. 4. These computers are easy to use
5. It has low memory. 5. These computers have big memory.
6. It has slow speed. 6. These computers have fast speed
7. It is used in engineering and science 7. It is used in all fields of life
8. It is used calculate analog quantities
like speed, weight, height etc.
8. It is used to calculate mathematical and
logical operations like additions etc
9. It is less reliable 9. It is more reliable

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Classification of Computer
Computers are classified on the basis of size, speed, processing power and price. However, the
classification of computer is not very straight-forward. The distinction between these categories is
sometimes not very clear. Some characteristics overlap different categories. Computer can be divided
into the following categories:
1. Micro Computers
Microcomputer is also called personal computers. It was introduced in 1970. It is designed
to be used by one person at a time. It consists of a processor, memory and one or more input, output and
storage devices.
Use of Microcomputer
Microcomputer is the most common type of computer used in the office and at home. It is also
used for business and engineering application.
2. Mini Computer
Minicomputer is large and more powerful than personal computer. It was introduced in 1960s.
It generally consists of two or more processors. It is more reliable than desktop computer.
Minicomputers are also called mid-range servers. It is more costly than micro computers.
Minicomputer can serve up to several hundred connected computers simultaneously. It is
normally accessed by users through personal computer or terminal. It is also called dumb terminal. It
has no processing power and cannot work as stand-alone computer. It has to be connected to a server.
Micro/Personal Computer Mini Computer Mainframe computer
Super Computer Embedded Computers
Classification of Computer

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Examples
 Prime 9955
 HP 3000
 AS 400
 VAX 8600
Use of Minicomputer
Minicomputers are often used by small and medium-size companies or departments. They
provide centralized store of information and computer programs.
3. Mainframe Computer
A Mainframe computer is a large computer in terms of price, power and speed. It was
introduced in 1975. It is more powerful than minicomputer. It consists of multiple processors. It is
specially designed to perform multiple users simultaneously. It is designed for high reliability. It often
runs twenty four hours a day. It can be serviced and upgraded while it is running. It is also known as
enterprise server or high-ended server.
Mainframe computer can serve several thousand users simultaneously. These computers can
store large amounts of data, information and programs. The users access a mainframe computer through
a terminal or personal computer. The price of mainframe computer is several thousand dollars and can
be up to several million dollars. IBM, Sun and Unisys are leading manufacturers of mainframe
computer.
Examples
 IBM S-390
 NEC 610
 DEC 10
 IBM system Z10
Uses of Mainframe Computer

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Mainframe computer are used in large organizations such as banks, educational institutions
and Govt. departments. For example, airlines use these computers to maintain flight schedules, ticket
reservation system etc.
4. Super Computers
Supercomputer is the fastest and the most powerful computer. It is the biggest in size and the
most expensive in price than any other computer. It was first developed in early 1970s. It is used to
perform complex tasks. It has a very large storage capacity and can store several thousand times more
data than an average desktop computer. It also consumes so much energy. It can process trillions of
instructions in one second. The modern supercomputer consists of thousands of microprocessors. The
cost of one super computer can be up to several billion dollars.
Example
 Roadrunner
 Blue Gene
 Deep Blue
 ASCI White
Uses of Supercomputers
Supercomputer is mostly for weather prediction, weapon design and atomic research etc.
supercomputer is also used in business and industry field. Aircraft manufacturers use it to simulate
aircraft and check its performance. Governments use a supercomputer for different calculations and
heavy jobs. Many Hollywood movies use it for animation purposes.
5. Embedded Computers
An embedded computer is designed for special purposes. It works as a component in a larger
product. These computers are very small and have limited hardware. They perform various functions
according to the requirements of the product in which they are embedded.
Embedded computers are used in commonly used product such as:
 Electronics: PDAs, mobile, videos recorders are DVD players etc.

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 Home Devices: security monitoring system & programmable microwave ovens etc.
 Automobiles: car engine controller, airbag controller etc.
 Process Controllers and Robotics: Machine controllers, blood pressure monitors etc.
References:
http://www.byte-notes.com/five-generations-computers
Book: Computer Application in Business Written by: Tasleem Mustafa, Tariq Mahmood, Ahsan Raza
Sattar, And Imran Saeed. B.Com (Part-1) Published by: IT Series Publication