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What is a computer?

 A computer is an electronic device that manipulates information, or data. It has the ability tostore, retrieve, and process data. In general you can use a computer to type documents, sendemail, play games, and browse the Web,create spreadsheets, presentations, and even videos.Computers are machines that perform tasks or calculations according to a set of instructions,or programs. The first fully electronic computers, introduced in the 1!"s, were huge machinesthat re#uired teams of people to operate. Compared to those early machines, today$s computersare ama%ing. &ot only are they thousands of times faster, they can fit on your desk, on your lap,or even in your pocket.

Types of computer

'ince the advent of the first computer different types and si%es of computers are offeringdifferent services. Computers can be as big as occupying a large building and as small as alaptop or a microcontroller inmobile ( embedded systems.The four basic types of computersare.

1. Super computer).

Mainframe Computer*. Minicomputer!. Microcomputer

1.Super Computer

The most powerful computers in terms ofperformance and data processing are thesupercomputers. These are speciali%edand task specific computers used by largeorgani%ations. These computers are used

for research and e+ploration purposes,like &A'A uses supercomputers forlaunching space shuttles, controlling themand for space e+ploration purpose.

Uses of Supercomputer

In akistan and other countries'upercomputers are used by -ducational

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Institutes like &'T /akistan0 for research purposes. akistan Atomic -nergy commission (eavy Industry Ta+ila uses supercomputers for 2esearch purposes.

Space ExplorationSupercomputers are used to study the origin of the universe, the dark-matters. For these studiesscientist use IBM’s poerfu! supercomputer "#oadrunner$ at %ationa! &a'oratory &os (!amos.

Earthquake studiesSupercomputers are used to study the )arth*uakes phenomenon. Besides that supercomputers areused for natura! resources e+p!oration, !ike natura! gas, petro!eum, coa!, etc.

Weather ForecastingSupercomputers are used for eather forecasting, and to study the nature and e+tent of urricanes,#ainfa!!s, indstorms, etc.

Nuclear weapons testingSupercomputers are used to run eapon simu!ation that can test the #ange, accuracy impact of %uc!ear eapons.

.Mainframe computer

  Although 3ainframes are not as powerful as supercomputers, but certainly they are #uite

e+pensive nonetheless, and many large firms ( government organi%ations uses 3ainframes torun their business operations. The 3ainframe computers can be accommodated in large air4conditioned rooms because of its si%e. 'uper4computers are the fastest computers with largedata storage capacity, 3ainframes can also process ( store large amount of data. 5ankseducational institutions ( insurance companies use mainframe computers to store data abouttheir customers, students ( insurance policy holders.

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0.Minicomputer

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3inicomputers are used by small businesses ( firms. 3inicomputers are also called

as =3idrange Computers>. These are small machines and can be accommodated on a disk withnot as processing and data storage capabilities as super4computers ( 3ainframes. Thesecomputers are not designed for a single user. Individual departments of a large company ororgani%ations use 3ini4computers for specific purposes. 6or e+ample, a production departmentcan use 3ini4computers for monitoring certain production process.

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1.Microcomputer

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@esktop computers, laptops, personal digital assistant /@A0, tablets ( smartphones areall types of microcomputers. The micro4computers are widely used ( the fastest growingcomputers. These computers are the cheapest among the other three types of computers. The3icro4computers are specially designed for general usage like entertainment, education andwork purposes. Well known manufacturers of 3icro4computer are @ell, Apple, 'amsung, 'ony (Toshiba.@esktop computers, aming consoles, 'ound ( &avigation system of a car, &etbooks,&otebooks, @A8s, Tablet C8s, 'martphones, Calculators are all type of 3icrocomputers.

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Types of computers

Computers range in si%e and capability. At one end of the scale are supercomputers, very largecomputers with thousands of linked microprocessors that perform e+tremely comple+calculations. At the other end are tiny computers embedded in cars, T:s, stereo systems,calculators, and appliances. These computers are built to perform a limited number of tasks.The personal computer, or C, is designed to be used by one person at a time. This sectiondescribes the various kinds of personal computersB desktops, laptops, handheld computers, andTablet Cs.

3esktop computers

@esktop computers are designed for use at a desk or table. They are typically larger and morepowerful than other types of personal computers. @esktop computers are made up of separatecomponents. The main component, called the system unit, is usually a rectangular case that sitson or underneath a desk. ther components, such as the monitor, mouse, and keyboard,connect to the system unit.

3esktop computer

&aptops and net'ooks

9aptops are lightweight mobile Cs with a thin screen. 9aptops can operate on batteries, so youcan take them anywhere. nlike desktops, laptops combine the C, screen, and keyboard in asingle case. The screen folds down onto the keyboard when not in use.&etbooks /also referred to as mini notebooks0, are small, affordable laptops that are designed toperform a limited number of tasks. They$re usually less powerful than laptops, so they$re usedmainly to browse the web and check e4mail.

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( !aptop and a net'ook

Smartphones

'martphones are mobile phones that have some of the same capabilities as a computer. Doucan use a smartphone to make telephone calls, access the Internet, organi%e contactinformation, send e4mail and te+t messages, play games, and take pictures. 'martphones

usually have a keyboard and a large screen.

Smartphone

andhe!d computers

andheld computers, also called personal digital assistants /@As0, are battery4poweredcomputers small enough to carry almost anywhere. Although not as powerful as desktops orlaptops, handheld computers are useful for scheduling appointments, storing addresses andphone numbers, and playing games. 'ome have more advanced capabilities, such as makingtelephone calls or accessing the Internet. Instead of keyboards, handheld computers have touchscreens that you use with your finger or astylus /a pen4shaped pointing tool0.

andhe!d computer

 4a'!et /Cs

Tablet Cs are mobile Cs that combine features of laptops and handheld computers. 9ikelaptops, they$re powerful and have a built4in screen. 9ike handheld computers, they allow you to

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write notes or draw pictures on the screen, usually with a tablet pen instead of a stylus. Theycan also convert your handwriting into typed te+t. 'ome Tablet Cs are =convertibles> with ascreen that swivels and unfolds to reveal a keyboard underneath.

 4a'!et /C

Input and 5utput devices

 An input device sends information to a computer system for processing, and an outputdevice reproduces or displays the results of that processing. @epending on the interaction, adevice can be bothE referred to as an inputFoutput or  IF device.

InputFoutput device, also known as computer peripheral, any of various devices /including

sensors0 used to enter information and instructions into a computer for storage or processingand to deliver the processed data to a human operator or, in some cases, a machine controlledby the computer. 'uch devices make up the peripheral e#uipment of modern  digitalcomputer  systems.

Comp!ete !ist of Input 3evices

6ey'oard

?eyboard is the most common input device of a Computer 'ystem. The keyboard resembles atypewriter. 3odern ?eyboards have more than 7ust the letter and numeric keys. They havemultimedia keys for volume control, lay F ause videos etc. -very single key on a keyboard is

assigned a binary numbers to it which transmits that binary pattern to the computer.&ow, have you ever wondered why the keys on a keyboard are not in alphabetic orderG Thekeys are laid out in the HW-2TD order so that those key that are often struck in successionwere not ne+t to each other. Therefore, the HW-2TD layout is intended for slow typists. Whilefor speed typing there is another keyboard available with @vorak layout.'ame is the case with the numeric keys layout. If you have noticed, the layout of a hone isdifferent from that of a numeric keys on a ?eyboard. It$s because earlier  phones cannot handlefast dialers. owever, the layout of numeric keys on a keyboard are designed for speed typing.

Mouse

3ouse is another commonly used input device of a computer system. The mouse is a pointing

device that moves the cursor on the screen. Dou can place the cursor on icons and by clickingyou can launch a program. A typical 3ouse has two buttons, the left and right clicking buttonsand a wheel in the center for scrollingA user can perform many operations through a 3ouse, likeselecting or arranging different program icons on the desktop. Copy F aste te+t in a worddocument, scroll webpages, and of course a mouse can come in handy while playing computergames.There are two types of 3ouse, one type has a rubber4covered ball at the bottom. As the mouseis slid on a surface, the ball rolls, resulting in movement of the cursor on the screen. This is the

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traditional type of mouse which is getting obsolete these days and this type of 3ouse does notperforms well on some surfaces. The other type is an ptical 3ouse, which is popular thesedays. The optical 3ouse tracks the 3ouse position using the optical sensor. The optical mousecan perform well as compared to the traditional mouse.

 Scanner

'canner is the third important input device of a computer system. A scanner converts printeddocuments in to images. 'ome types of scanners scan documents and produce the results inblack ( white images. The scanner operates in the same manner as a hotocopier. A coloredscanner works somewhat in a complicated manner as compared to a simple scanner.

3igita! Camera

@igital Cameras are used to capture images. Those images are then transferred to a computerwhen the Camera is connected to the computer. 3ostly the @igital Camera images are in J-format.

7amepad

 A computer can serve many purposes. 5esides work, a user can also play games on aComputer. Dou can use a keyboard and mouse for gaming but a speciali%ed ardware device, i4e a amepad can also be used. A gamepad is used for controlling games, with few buttons thatcontrols the movements of character in a Computer ame.

5utput 3evices

Monitor

3onitor is the most important output device of a computer system. The monitor is the displayscreen of a computer. Cathode 2ays Tube /C2T0 and 9i#uid Crystal @isplay /9C@0 are the twotypes of 3onitors.

 

/rinters

 A rinter takes print commands from a computer and print out te+t F images on a paper.@ifferent types of printers are available for various purposes. A printer for office use must beheavy duty and fast while for photographs it must produce high #uality prints. @ot43atri+, Ink4

Jet, 9aser4Jet are the different types of printers. 

Speakers

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'peaker is an important part of a computer system. 'ome systems have a built4in speaker,though they are small in si%e. 'peaker is an essential part of a computer because they can notify about various system notifications throughvarious sounds.3emory

Computer memory 

The computer memory is a temporary storage area. It holds the data and instructions that theCentral rocessing nit /C0 needs. 5efore a program can be run, the program is loaded fromsome storage medium into the memory. This allows the C direct access to the program.