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History of Computing

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					                                   History of Computing


A computer is a programmable machine that receives input, stores and manipulates data /
information, and provides output in a useful format.

While a computer can, in theory, be made out of almost anything (see misconceptions section),
and mechanical examples of computers have existed through much of recorded human history,
the first electronic computers were developed in the mid-20th century (1940–1945). Originally,
they were the size of a large room, consuming as much power as several hundred modern
personal computers (PCs). Modern computers based on integrated circuits are millions to billions
of times more capable than the early machines, and occupy a fraction of the space. Simple
computers are small enough to fit into mobile devices, and can be powered by a small battery.
Personal computers in their various forms are icons of the Information Age and are what most
people think of as "computers". However, the embedded computers found in many devices from
MP3 players to fighter aircraft and from toys to industrial robots are the most numerous.

The history of computing is longer than the history of computing hardware and modern computing
technology and includes the history of methods intended for pen and paper or for chalk and slate,
with or without the aid of tables. The timeline of computing presents a summary list of major
developments in computing by date.

                                       Early computation

Main articles: History of computing and Timeline of computing 2400 BC–1949

The earliest known tool for use in computation was the abacus, and it was thought to have been
invented in Babylon circa 2400 BCE. Its original style of usage was by lines drawn in sand with
pebbles. This was the first known computer and most advanced system of calculation known to
date - preceding Greek methods by 2,000 years. Abaci of a more modern design are still used as
calculation tools today.

In 1115 BCE, the South Pointing Chariot was invented in ancient China. It was the first known
geared mechanism to use a differential gear, which was later used in analog computers. The
Chinese also invented a more sophisticated abacus from around the 2nd century BCE, known as
the Chinese abacus.

In the 5th century BCE in ancient India, the grammarian Pāṇini formulated the grammar of Sanskrit
in 3959 rules known as the Ashtadhyayi which was highly systematized and technical. Panini used
metarules, transformations and recursions.
The Antikythera mechanism is believed to be the earliest known mechanical analog computer. It
was designed to calculate astronomical positions. It was discovered in 1901 in the Antikythera
wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to circa
100 BC. Technological artifacts of similar complexity did not reappear until the 14th century, when
mechanical astronomical clocks appeared in Europe.

Mechanical analog computing devices appeared again a thousand years later in the medieval
Islamic world. Examples of devices from this period include the equatorium by Arzachel, the
mechanical geared astrolabe by Abū Rayhān al-Bīrūnī, and the torquetum by Jabir ibn Aflah.
Muslim engineers built a number of Automata, including some musical automata that could be
'programmed' to play different musical patterns. These devices were developed by the Banū Mūsā
brothers and Al-Jazari Muslim mathematicians also made important advances in cryptography,
such as the development of cryptanalysis and frequency analysis by Alkindus.

When John Napier discovered logarithms for computational purposes in the early 17th century,
there followed a period of considerable progress by inventors and scientists in making calculating
tools. In 1623 Wilhelm Schickard designed a calculating machine, but abandoned the project,
when the prototype he had started building was destroyed by a fire in 1624. Around 1640, Blaise
Pascal, a leading French mathematician, constructed the first mechanical adding device[10] based
on a design described by Greek mathematician Hero of Alexandria. Then in 1672 Gottfried
Wilhelm Leibniz invented the Stepped Reckoner which he completed in 1694.

None of the early computational devices were really computers in the modern sense, and it took
considerable advancement in mathematics and theory before the first modern computers could
be designed.

                                           Algorithms



In the 7th century, Indian mathematician Brahmagupta gave the first explanation of the Hindu-
Arabic numeral system and the use of zero as both a placeholder and a decimal digit.

Approximately around the year 825, Persian mathematician Al-Khwarizmi wrote a book, On the
Calculation with Hindu Numerals, that was principally responsible for the diffusion of the Indian
system of numeration in the Middle East and then Europe. Around the 12th century, there was
translation of this book written into Latin: Algoritmi de numero Indorum. These books presented
newer concepts to perform a series of steps in order to accomplish a task such as the systematic
application of arithmetic to algebra. By derivation from his name, we have the term
algorithm.Algorithm-is the computer in using a mathematical equation.
                                           Binary logic

Around the 3rd century BC, Indian mathematician Pingala discovered the binary numeral system.
In this system, still used today in all modern computers, a sequence of ones and zeros can
represent any number.

In 1703, Gottfried Leibnitz developed logic in a formal, mathematical sense with his writings on
the binary numeral system. In his system, the ones and zeros also represent true and false values
or on and off states. But it took more than a century before George Boole published his Boolean
algebra in 1854 with a complete system that allowed computational processes to be
mathematically modeled.

By this time, the first mechanical devices driven by a binary pattern had been invented. The
industrial revolution had driven forward the mechanization of many tasks, and this included
weaving. Punched cards controlled Joseph Marie Jacquard's loom in 1801, where a hole punched
in the card indicated a binary one and an unpunched spot indicated a binary zero. Jacquard's loom
was far from being a computer, but it did illustrate that machines could be driven by binary
systems.

                                    Birth of computer science

Before the 1920s, computers (sometimes computors) were human clerks that performed
computations. They were usually under the lead of a physicist. Many thousands of computers
were employed in commerce, government, and research establishments. Most of these computers
were women, and they were known to have a degree in calculus. Some performed astronomical
calculations for calendars.

After the 1920s, the expression computing machine referred to any machine that performed the
work of a human computer, especially those in accordance with effective methods of the Church-
Turing thesis. The thesis states that a mathematical method is effective if it could be set out as a
list of instructions able to be followed by a human clerk with paper and pencil, for as long as
necessary, and without ingenuity or insight.

Machines that computed with continuous values became known as the analog kind. They used
machinery that represented continuous numeric quantities, like the angle of a shaft rotation or
difference in electrical potential.

Digital machinery, in contrast to analog, were able to render a state of a numeric value and store
each individual digit. Digital machinery used difference engines or relays before the invention of
faster memory devices.
The phrase computing machine gradually gave away, after the late 1940s, to just computer as the
onset of electronic digital machinery became common. These computers were able to perform the
calculations that were performed by the previous human clerks.

Since the values stored by digital machines were not bound to physical properties like analog
devices, a logical computer, based on digital equipment, was able to do anything that could be
described "purely mechanical." The theoretical Turing Machine, created by Alan Turing, is a
hypothetical device theorized in order to study the properties of such hardware.

See also: Philosophy of physics, Philosophy of biology, Philosophy of mathematics, Philosophy of
language, and Philosophy of mind

                                  The theoretical groundwork

The mathematical foundations of modern computer science began to be laid by Kurt Gödel with
his incompleteness theorem (1931). In this theorem, he showed that there were limits to what
could be proved and disproved within a formal system. This led to work by Gödel and others to
define and describe these formal systems, including concepts such as mu-recursive functions and
lambda-definable functions.

1936 was a key year for computer science. Alan Turing and Alonzo Church independently, and also
together, introduced the formalization of an algorithm, with limits on what can be computed, and
a "purely mechanical" model for computing.

These topics are covered by what is now called the Church–Turing thesis, a hypothesis about the
nature of mechanical calculation devices, such as electronic computers. The thesis claims that any
calculation that is possible can be performed by an algorithm running on a computer, provided
that sufficient time and storage space are available.

Turing also included with the thesis a description of the Turing machine. A Turing machine has an
infinitely long tape and a read/write head that can move along the tape, changing the values along
the way. Clearly such a machine could never be built, but nonetheless, the model can simulate the
computation of any algorithm which can be performed on a modern computer.

Turing is so important to computer science that his name is also featured on the Turing Award and
the Turing test. He contributed greatly to British code-breaking successes in the Second World
War, and continued to design computers and software through the 1940s, but committed suicide
in 1954.

At a symposium on large-scale digital machinery in Cambridge, Turing said, "We are trying to build
a machine to do all kinds of different things simply by programming rather than by the addition of
extra apparatus".

In 1948, the first practical computer that could run stored programs, based on the Turing machine
model, had been built - the Manchester Baby.
In 1950, Britain's National Physical Laboratory completed Pilot ACE, a small scale programmable
computer, based on Turing's philosophy.

                                 Shannon and information theory



Up to and during the 1930s, electrical engineers were able to build electronic circuits to solve
mathematical and logic problems, but most did so in an ad hoc manner, lacking any theoretical
rigor. This changed with Claude Elwood Shannon's publication of his 1937 master's thesis, A
Symbolic Analysis of Relay and Switching Circuits. While taking an undergraduate philosophy class,
Shannon had been exposed to Boole's work, and recognized that it could be used to arrange
electromechanical relays (then used in telephone routing switches) to solve logic problems. This
concept, of utilizing the properties of electrical switches to do logic, is the basic concept that
underlies all electronic digital computers, and his thesis became the foundation of practical digital
circuit design when it became widely known among the electrical engineering community during
and after World War II.

Shannon went on to found the field of information theory with his 1948 paper titled A
Mathematical Theory of Communication, which applied probability theory to the problem of how
to best encode the information a sender wants to transmit. This work is one of the theoretical
foundations for many areas of study, including data compression and cryptography.

                                      Wiener and Cybernetics

From experiments with anti-aircraft systems that interpreted radar images to detect enemy
planes, Norbert Wiener coined the term cybernetics from the Greek word for "steersman." He
published "Cybernetics" in 1948, which influenced artificial intelligence. Wiener also compared
computation, computing machinery, memory devices, and other cognitive similarities with his
analysis of brain waves.

                                      The first computer bug

The first actual computer bug was a moth. It was stuck in between the relays on the Harvard Mark
II.[1] While the invention of the term 'bug' is often but erroneously attributed to Grace Hopper, a
future rear admiral in the U.S. Navy, who supposedly logged the "bug" on September 9, 1945,
most other accounts conflict at least with these details. According to these accounts, the actual
date was September 9, 1947 when operators filed this 'incident' — along with the insect and the
notation "First actual case of bug being found" (see software bug for details).
There are several uses of computers:

  * Word Processing - Word Processing software automatically corrects spelling and grammar
mistakes. If the content of a document repeats you don’t have to type it each time. You can use
the copy and paste features. You can printout documents and make several copies. It is easier to
read a word-processed document than a handwritten one. You can add images to your document.

  * Internet - It is a network of almost all the computers in the world. You can browse through
much more information than you could do in a library. That is because computers can store
enormous amounts of information. You also have very fast and convenient access to information.
Through E-Mail you can communicate with a person sitting thousands of miles away in seconds.
There is chat software that enables one to chat with another person on a real-time basis. Video
conferencing tools are becoming readily available to the common man.

  * Digital video or audio composition – Audio or video composition and editing have been made
much easier by computers. It no longer costs thousands of dollars of equipment to compose music
or make a film. Graphics engineers can use computers to generate short or full-length films or
even to create three-dimensional models. Anybody owning a computer can now enter the field of
media production. Special effects in science fiction and action movies are created using
computers.

  * Desktop publishing - With desktop publishing, you can create page layouts for entire books on
your personal computer.

  * Computers in Medicine - You can diagnose diseases. You can learn the cures. Software is used
in magnetic resonance imaging to examine the internal organs of the human body. Software is
used for performing surgery. Computers are used to store patient data.

 * Mathematical Calculations - Thanks to computers, which have computing speeds of over a
million calculations per second we can perform the biggest of mathematical calculations.

  * Banks - All financial transactions are done by computer software. They provide security, speed
and convenience.

  * Travel - One can book air tickets or railway tickets and make hotel reservations online.

  * Telecommunications - Software is widely used here. Also all mobile phones have software
embedded in them.

  * Defense - There is software embedded in almost every weapon. Software is used for
controlling the flight and targeting in ballistic missiles. Software is used to control access to atomic
bombs.

  * E-Learning – Instead of a book it is easier to learn from an E-learning software.

  * Gambling-You can gamble online instead of going to a casino.
  * Examinations-You can give online exams and get instant results. You can check your
examination results online.

  * Computers in Business - Shops and supermarkets use software, which calculate the bills. Taxes
can be calculated and paid online. Accounting is done using computers. One can predict future
trends of business using artificial intelligence software. Software is used in major stock markets.
One can do trading online. There are fully automated factories running on software.

  * Certificates - Different types of certificates can be generated. It is very easy to create and
change layouts.

  * ATM machines - The computer software authenticates the user and dispenses cash.

  * Marriage - There are matrimonial sites through which one can search for a suitable groom or
bride.

  * News-There are many websites through which you can read the latest or old news.

   * Classmates-There are many alumni websites through which you can regain contact with your
classmates.

  * Robotics - Robots are controlled by software.

  * Washing Machines - They operate using software.

  * Microwave Oven - They are operated by software.

  * Planning and Scheduling - Software can be used to store contact information, generating
plans, scheduling appointments and deadlines.

  * Plagiarism - Software can examine content for plagiarism.

  * Greeting Cards - You can send and receive greetings pertaining to different occasions.

 * Sports – Software is used for making umpiring decisions. There are simulation software using
which a sportsperson can practice his skills. Computers are also to identify flaws in techhnique.

  * Aeroplanes – Pilots train on software, which simulates flying.

  * Weather analysis – Supercomputers are used to analyze and predict weather.

The illustration below shows the most common hardware in a desktop computer system. Your
system may look a little different, but it probably has most of these parts. A laptop computer has
similar parts but combines them into a single notebook-sized package.
                                            Computer Parts




                                                                        Desktop computer system

Let's take a look at each of these parts.

System unit

The system unit is the core of a computer system. Usually it's a rectangular box placed on or
underneath your desk. Inside this box are many electronic components that process information.
The most important of these components is the central processing unit (CPU), or microprocessor,
which acts as the "brain" of your computer. Another component is random access memory (RAM),
which temporarily stores information that the CPU uses while the computer is on. The information
stored in RAM is erased when the computer is turned off.

Almost every other part of your computer connects to the system unit using cables. The cables
plug into specific ports (openings), typically on the back of the system unit. Hardware that is not
part of the system unit is sometimes called a peripheral device or device.
                                         System unit

Storage

Your computer has one or more disk drives—devices that store information on a metal or plastic
disk. The disk preserves the information even when your computer is turned off.

Hard disk drive

Your computer's hard disk drive stores information on a hard disk, a rigid platter or stack of
platters with a magnetic surface. Because hard disks can hold massive amounts of information,
they usually serve as your computer's primary means of storage, holding almost all of your
programs and files. The hard disk drive is normally located inside the system unit.




                                                           Hard disk drive

CD and DVD drives

Nearly all computers today come equipped with a CD or DVD drive, usually located on the front of
the system unit. CD drives use lasers to read (retrieve) data from a CD, and many CD drives can
also write (record) data onto CDs. If you have a recordable disk drive, you can store copies of your
files on blank CDs. You can also use a CD drive to play music CDs on your computer.




                                 CD

DVD drives can do everything that CD drives can, plus read DVDs. If you have a DVD drive, you can
watch movies on your computer. Many DVD drives can record data onto blank DVDs.




Tip

If you have a recordable CD or DVD drive, periodically back up (copy) your important files to CDs or
DVDs. That way, if your hard disk ever fails, you won't lose your data.

Floppy disk drive

Floppy disk drives store information on floppy disks, also called floppies or diskettes. Compared to
CDs and DVDs, floppy disks can store only a small amount of data. They also retrieve information
more slowly and are more prone to damage. For these reasons, floppy disk drives are less popular
than they used to be, although some computers still include them.




                         Floppy disk

Why are floppy disks "floppy"? Even though the outside is made of hard plastic, that's just the
sleeve. The disk inside is made of a thin, flexible vinyl material.

Mouse
A mouse is a small device used to point to and select items on your computer screen. Although
mice come in many shapes, the typical mouse does look a bit like an actual mouse. It's small,
oblong, and connected to the system unit by a long wire that resembles a tail. Some newer mice
are wireless.




                                      Mouse

A mouse usually has two buttons: a primary button (usually the left button) and a secondary
button. Many mice also have a wheel between the two buttons, which allows you to scroll
smoothly through screens of information.




When you move the mouse with your hand, a pointer on your screen moves in the same direction.
(The pointer's appearance might change depending on where it's positioned on your screen.)
When you want to select an item, you point to the item and then click (press and release) the
primary button. Pointing and clicking with your mouse is the main way to interact with your
computer.

Keyboard

A keyboard is used mainly for typing text into your computer. Like the keyboard on a typewriter, it
has keys for letters and numbers, but it also has special keys:

       The function keys, found on the top row, perform different functions depending on where
        they are used.

       The numeric keypad, located on the right side of most keyboards, allows you to enter
        numbers quickly.

       The navigation keys, such as the arrow keys, allow you to move your position within a
        document or webpage.
                                                      Keyboard

You can also use your keyboard to perform many of the same tasks you can perform with a
mouse.

Monitor

A monitor displays information in visual form, using text and graphics. The portion of the monitor
that displays the information is called the screen. Like a television screen, a computer screen can
show still or moving pictures.

There are two basic types of monitors: CRT (cathode ray tube) monitors and LCD (liquid crystal
display) monitors. Both types produce sharp images, but LCD monitors have the advantage of
being much thinner and lighter. CRT monitors, however, are generally more affordable.




                                                                   LCD monitor (left); CRT monitor
(right)

Printer

A printer transfers data from a computer onto paper. You don't need a printer to use your
computer, but having one allows you to print e-mail, cards, invitations, announcements, and other
materials. Many people also like being able to print their own photos at home.

The two main types of printers are inkjet printers and laser printers. Inkjet printers are the most
popular printers for the home. They can print in black and white or in full color and can produce
high-quality photographs when used with special paper. Laser printers are faster and generally
better able to handle heavy use.
                                                                      Inkjet printer (left); laser
printer (right)

Speakers

Speakers are used to play sound. They may be built into the system unit or connected with cables.
Speakers allow you to listen to music and hear sound effects from your computer.




                           Computer speakers

Modem

To connect your computer to the Internet, you need a modem. A modem is a device that sends
and receives computer information over a telephone line or high-speed cable. Modems are
sometimes built into the system unit, but higher-speed modems are usually separate components.




                    Cable modem

				
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