The document summarizes the evolution of computers over five generations from 1945 to the present. Each generation is characterized by a major technological development, such as the transition from vacuum tubes to transistors to integrated circuits and microprocessors, that increased computers' capabilities while reducing their size, cost, and energy usage. The document also categorizes computers as supercomputers, mainframes, minicomputers, or microcomputers based on their processing power, size, cost, and intended use.

1. 1
Evolution of
Computers
Assignment 1
D.S.Weeraddana
TG/2017/258
Computer Architecture
ICT1252

2. 2
Contents
Generations of Computers ........................................................................................................... 4
First Generation (1945-1955) ................................................................................................... 4
Second Generation (1955-1965) ............................................................................................... 5
Third Generation (1965-1975) ................................................................................................. 5
Fourth Generation (1975-Current) ......................................................................................... 6
Fifth Generation (Present and Beyond) .................................................................................. 7
Categories of Computer ............................................................................................................... 8
SuperComputers........................................................................................................................ 8
MainframeComputers .............................................................................................................. 9
MiniComputers.......................................................................................................................... 9
MicroComputers ..................................................................................................................... 10

3. 3
Man always searched for a fast calculating device, it took a long time to invent a digital computer.
Evolution of computers refers to the historical developments through which computers and
technology have passed, from the time they started to exit in ancient forms to their current state.
Examples of Ancient counting and calculating devices:
 The Abacus - The beginning or foundation of computing devices is the abacus,
which was developed in 300 BC by Chinese. It was built out of wood and beads.
The abacus helps people keep track of numbers as they do the computing. It is quick
but has limited storage capabilities.
 Napier’s Bones - John Napier invented a tool called “Napier’s Bones”. Napier’s
bones were multiplication tables written on strips of bones, ivory, silver or wood.
The invention was used for simplifying multiplication, division and taking square
roots and cube roots.
 Blaise Pascal’s Calculator – Pascal Blaise invented the first mechanical calculator
to speed arithmetic calculations. Numbers are dialed in on the metal wheels on the
front of the calculator.
The first computer Programmer was Ada Byron Lovelace (1815-1852). In 1842, Ada was
asked to write a scientific interpretation of the Analytical Engine and its operations.
 We can divide the evolution of computers into sub parts.
Evolution of
Computers
Generations of
Computers
Categories of
Computer

4. 4
Generations of Computers
The history of computer development is often referred to in reference to the different generations
of computer devices. Each generation of computer is characterized by a major technological
development that fundamentally changed the way computers operate, resulting in increasingly
smaller, cheaper, and more powerful and more efficient and reliable devices.
First Generation (1945-1955)
 The first Generation computers were based on Vacuum Tube, which was a glass tube that
controlled and amplified the electronic signals.
 Input was based on punched cards and paper tape, and output was displayed on printouts.
 Used machine language.
 Examples:
 Electronic Numerical Integrator and Calculator (ENIAC) invented in 1946,
was the first electronic computer.
 Universal Automatic Computer (UNIAC) was the first digital computer, was
used in business and industries.
 Advantages and Disadvantages of 1st
generation computers.
Advantage Disadvantage
Vacuum Tubes were the only electronic
component available in those days.
These were very large.
This technology made possible to make
electronic digital computers
Not reliable
These computers could calculate data in
milliseconds.
Could solve one problem at a time.
Air conditioning was required
Consumed a large amount of energy
Heated very soon due to thousands of vacuum
tubes.

5. 5
Second Generation (1955-1965)
 This was the age of Transistors, which is a small device that transfers electronic signals
across a resistor.
 The concept of Minicomputers was introduced.
 Still relied on punched cards for input and printouts for output.
 Used Assembly language.
 Examples:
 IBM 7094 series
 IBM 1400 series
 CDC 164
Advantage and Disadvantage of second generation computers.
Advantage Disadvantage
Smaller size as compared to the first
generation computers
Air conditioning was required
More reliable Costly
More energy-efficient Commercial production was difficult
Better portability Constant maintenance was required
Were not heated because of less energy Also only used for specific purposes.
Third Generation (1965-1975)
 It was the age of Integrated Circuits (ICs), which combined three electronic components
onto a small silicon disc.
 Scientists later managed to fit even more components on a single chip called a
Semiconductor, which increased the speed and efficiency of computers.
 The concept of mainframes was introduced.

6. 6
 Instead punched cards and printouts, user interacted through keyboards and monitors and
interfaced with an operating systems, which allowed the device to run many different
applications at one time with a central program that monitored the memory.
 Examples:
 IBM System/360
 UNIVAC 1108
 IBM 370
 Advantage and Disadvantage of third generation computers.
Advantage Disadvantage
Smaller in size as compared to previous
generation
Air conditioning was required
More reliable High sophisticated technology required for the
manufacturing of IC chips.Less energy used
Produced less heat as compared to previous
generations computers
More good speed, could calculate data in
nanoseconds.
Fourth Generation (1975-Current)
 The fourth generation started with the invention of Microprocessors.
 What in the first generation filled an entire room could now fit in the palm of the hand.
 Microprocessors is a small chip containing thousands of ICs on it.
 It greatly reduces the size of the computer.
 The modern microprocessors are usually one inch and can contain millions of electronic
circuits.
 Fourth generation computers also saw the development of GUIs, the mouse and Hand held
devices.

7. 7
 Examples:
 Macintosh
 Advantage and Disadvantage of fourth generation computers.
Advantage Disadvantage
Very small in size Highly sophisticated technology required for
manufacturing microprocessorsLess power consumption
Less heat generated
Reliable and powerful
No air conditioning is required
Less need for repairing
Commercial production
Fifth Generation (Present and Beyond)
 It is based on Artificial Intelligence (AI), computers can understand spoken word
instructions and imitate human reasoning.
 Scientist are working to increase the speed of computers.
 They are trying to create a computer with a real IQ with the help advanced programming
and technologies.
 With the rapid pace of technology, the high rate of introduction of new products, and the
importance of software and communications as well as hardware, the classification by
generation becomes less clear and less meaningful.
 It could be said the commercial application of new developments resulted in a major
change in the early 1970s and that the results of these changes are still being worked out.
 Quantum computation and molecular and nanotechnology will radically change the face of
computers in years to come.

8. 8
Categories of Computer
Computers are classified based on their technology, function, physical size, performance, and cost.
The categories of computers include:
SuperComputers
 Supercomputers are the fastest and the most expensive machines.
 They have high processing speed compared to other computers.
 The speed of a supercomputer is generally measured in FLOPS (Floating Point Operations
per Second). Some of the faster supercomputers can perform trillions of calculations per
second.
 Supercomputers are built by interconnecting thousands of processors that can work in
parallel.
 Supercomputers are used for highly calculation-intensive tasks, such as, weather
forecasting, climate research (global warming), molecular research, bi logical research,
nuclear research and aircraft design.

9. 9
 Example:
 IBM Roadrunner
 IBM Blue gene
 Intel ASCI red
MainframeComputers
 Mainframe computer are multi-user, multi programming and high performance computers.
They operate at a very high speed, have very large storage capacity and can handle the
workload of many user.
 Mainframe computer are used in large organizations such as insurance companies and
banks, where many people frequently need to use the same data.
 In a traditional mainframe environment, each user accesses the mainframe’s resources
through a device called a terminal.
 There are two types of terminals:
 Dumb terminal – Does not process or store data. It is simply an input/output
device that functions as a window into a computer located somewhere else.
 Intelligent terminal – Can perform some processing operations, but it
usually does not have any storage.
 In some mainframe environments, however, workers can use a standard personal computer
to access the mainframe.
 Example:
 CDC 6600
 IBM ES000 series
MiniComputers
 Minicomputers are digital computers, generally used in multi-user systems.
 They have high processing speed and high storage capacity than the microcomputers.
 Minicomputers can support 4-200 user simultaneously. The users can access the
minicomputer through their PCs or terminal.

10. 10
 They are used for real-time applications in industries, research centers.
 The capabilities of a minicomputer are somewhere between those of mainframe and
personal computers. For this reason minicomputers are often called Midrange
Computers.
 Examples:
 PDP 11
 IBM(8000 series)
MicroComputers
 Microcomputers are small, low-cost and single-user digital computer.
 They consist of CPU, input unit, output unit, storage unit and the software.
 Although microcomputers are stand-alone machines, they can be connected together to
create a network of computers that can serve more than one user.
 IBM PC based on Pentium microprocessor and Apple Macintosh are some examples of
microcomputers.
 Example:
 Desktop computers or Personal Computer(PC) - PC is the most common type
of microcomputer. It is a stand-alone machine that can be placed on the desk.
Externally, it consists of three units—keyboard, monitor, and a system
unit containing the CPU, memory, hard disk drive, etc. It is not very expensive and
is suited to the needs of a single user at home, small business units, and
organizations.
 Notebook computers or Laptop - Resemble a notebook. They are portable and
have all the features of a desktop computer. The advantage of the laptop is that it is
small in size (can be put inside a briefcase), can be carried anywhere, has a battery
backup and has all the functionality of the desktop.

11. 11
 Tablet computer - Has features of the notebook computer but it can accept input
from a stylus or a pen instead of the keyboard or mouse. It is a portable computer.
Tablet computer are the new kind of PCs.
 Smart Phones - are cellular phones that function both as a phone and as a small
PC. They may use a stylus or a pen, or may have a small keyboard. They can be
connected to the Internet wirelessly. They are used to access the electronic-mail,
download music, play games, etc
----------------------------------------------------END----------------------------------------------------------