Charles Babbage invented the earliest mechanical computer to reduce errors in calculations. Alan Turing helped develop early computers to break codes in World War II. The first electronic, programmable computer was Colossus, built by Tommy Flowers to decrypt German messages. Later innovations included the stored-program concept by John von Neumann and the graphical user interface by Douglas Engelbart. Steve Jobs and Bill Gates then helped drive the personal computer revolution through their companies Apple and Microsoft. Modern computers are based on integrated circuits and microprocessors, beginning with the Intel 4004 microchip.

1. HISTORY OF COMPUTERS
By:Y.Shashvut

2. CONTENTS
Introduction To Computers
People associated with Computers
History of Computers

3. WHAT IS A COMPUTER?
A computer is any device which aids humans in
performing various kinds of computations or calculations. In that
respect the earliest computer was the abacus, used to perform basic
arithmetic operations. While abacus may have technically been the
first computer most people today associate the word “computer” with
electronic computers which were invented in the last century, and
have evolved into modern computers we know of today.

4. P E O P L E A S S O C I AT E D W I T H
COMPUTERS
 Charles Babbage
 Alan Turing
 Tommy Flowers
 John V. Neumann
 Douglas Engelbart
 Steve Jobs
 Bill Gates

5. CHARLES BABBAGE
 Charles Babbage first came up with the idea of a mechanical
computer after seeing how numerical tables calculated by humans (called
computers) had a high-degree of error. He decided that by creating a device for
doing the same job, the errors could be eliminated. The difference engine was born:
a machine capable of calculating the values of polynomial functions automatically.
Regardless of the fact that his computer was never built while he was alive, Babbage
opened the floodgates to a new world of computing machines. Without him, we
may not have the modern computers we have today.

6. ALAN TURING
 The initial machine Turing created was the Bombe: an
electromechanical device devised to help the code-breakers device the key of the
day the German's were using on their Enigma machines. Using a menu provided by
the codebreaking team from a crib (a selection of plaintext that corresponded to
ciphertext), the Bombe operators could quickly set up the machine and let it
calculate possible Enigma settings, which could then be verified by hand. The design
on the Bombe was enhanced by Gordon Welchman, and the rest, as they say, is
history.

7. TOMMY FLOWERS
 Another member of the Bletchley Park World War II team, Tommy Flowers was
instrumental in building the world's first electronic computer: Colossus. The
principle purpose of the machine was to break the Lorenz Cipher, used by high-
level Germans, including Adolf Hitler. Colossus was the first programmable, digital,
computer and revolutionary at the time. It's success in code breaking was
demonstrated when Eisenhower was handed a decrypt showing that Hitler wasn't
going to move more troops into Normandy and the D-Day landings stood a high-
chance of success.

8. JOHN V. NEUMANN
 It was von Neumann who came up with the computer architecture
that's named after him. In a paper, he described an architecture in
which both data and the program are stored in a computer's memory
in the same address space, making for more flexible computers that
were easier to program.

9. DOUGLAS ENGELBART
 Douglas Engelbart might not be a name that's well known,
but he was a pioneer in the development of the modern computer. While working at the
Stanford Research Institute (SRI), he created a research department with an agenda
entitled Augmenting Human Intellect: A Conceptual Framework. In other words, creating
methods by which people would interact with computers. It was here that he created the
mouse (then a wooden shell with two metal wheels in it), still the de facto way that we
interact with computers today. He and his team also created bit-mapped screens,
hypertext and some precursors to the graphical user interface (GUI).
 The research started here allowed Xerox to continue development and come up with
the basis of the windowed-operating system that we all use today.

10. STEVE JOBS
 In 1976 Steve Jobs, along with Stephen Wozniak and Ronald Wayne founded Apple.
Although the company had early success with the Apple and, in particular, Apple II computers, it
was the original Macintosh (1984) that changed things: it was the first computer to have a
graphical user interface and mouse rather than a command line interface.The Macintosh really
highlights Jobs' ability to take existing technology and improve it, making it desirable. In the case
of this computer the graphical user interface had been developed by Xerox and the mouse by
Douglas Engelbart; it was Apple that made them successful. Apple has produced the iPod, the
most popular MP3 player in the world, the iPhone, which has sparked an entirely-new industry
with Apps and the iPad. With OS X and the move to Intel hardware, Apple is a leading company
in the personal computer market.

11. BILL GATES
 Whatever you may think about Bill Gates, there's no doubting the
impact that he's had on the computer market. He's best known for founding Microsoft - a
name that's synonymous with the personal computer market. Although Microsoft didn't
actually invent DOS (Tim Paterson of Seattle Computer Products) did, the company has
based its fortunes on it, exclusively licensing the OS and later buying it outright to service
IBM's PC. From DOS, Microsoft went on to create Windows - the most successful
operating system ever, and used by the majority of people the world over.Gates is a key
figure in the success of Microsoft - equal parts technology genius and business man, he's
pushed, cajoled and basically dictated the computer market.

12. HISTORY OF COMPUTERS
 First Generation Computers (1940s – 1950s)
 Second Generation Computers (1955 – 1960)
 Third Generation Computers (1960s)
 Fourth Generation Computers (1971 – present)

13. F I R S T G E N E R AT I O N
COMPUTERS (1940’S -1950’S)
First electronic computers used vacuum tubes, and they were huge and
complex. The first general purpose electronic computer was the ENIAC
(Electronic Numerical Integrator And Computer). It was digital,
although it didn’t operate with binary code, and was reprogrammable to
solve a complete range of computing problems. It was programmed
using plugboards and switches, supporting input from an IBM card
reader, and output to an IBM card punch. It took up 167 square meters,
weighed 27 tons, and consuming 150 kilowatts of power. It used
thousands of vacuum tubes, crystal diodes, relays, resistors, and
capacitors.

14. S E C O N D G E N E R AT I O N
COMPUTERS(1955-1960)
The second generation of computers came about thanks to the
invention of the transistor, which then started replacing vacuum
tubes in computer design. Transistor computers consumed far
less power, produced far less heat, and were much smaller
compared to the first generation, albeit still big by today’s
standards.The first transistor computer was created at the
University of Manchester in 1953. The most popular of
transistor computers was IBM 1401. IBM also created the first
disk drive in 1956, the IBM 350 RAMAC.

15. T H I R D G E N E R AT I O N
COMPUTERS(1960-1970)
The invention of the integrated circuits (ICs), also known as microchips, paved the way
for computers as we know them today. Making circuits out of single pieces of silicon,
which is a semiconductor, allowed them to be much smaller and more practical to
produce.First appeared minicomputers, first of which were still based on non-
microchip transistors, and later versions of which were hybrids, being based on both
transistors and microchips, such as IBM’s System/360. They were much smaller, and
cheaper than first and second generation of computers, also known as mainframes.
Minicomputers can be seen as a bridge between mainframes and microcomputers,
which came later as the proliferation of microchips in computers grew.

16. F O U RT H G E N E R AT I O N
COMPUTERS(1971-PRESENT)
First microchips-based central processing units consisted of multiple
microchips for different CPU components. The drive for ever greater
integration and miniaturization led towards single-chip CPUs, where all of the
necessary CPU components were put onto a single microchip, called a
microprocessor. The first single-chip CPU, or a microprocessor, was Intel 4004.
The advent of the microprocessor spawned the evolution of the
microcomputers, the kind that would eventually become personal computers
that we are familiar with today.

17. THANK YOU
By: Y.Shashvut
IX-D
Roll No. 19