137022446 Computer Course

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1 COMPUTER COURSE k.suresh

Introducing Computer Systems

What is Computer?

Computer is an advanced electronic device that takes raw data as input from the user and

processes these data under the control of set of instructions (called program) and gives the result

(output) and saves output for the future use. It can process both numerical and non-numerical

(arithmetic and logical) calculations.

(O)

! Computer is an electronic device that can perform activities that involve "athematical# logical

and graphical manipulations. $enerally# the term is used to describe a collection of devices that

function together as a system.

! computer has four functions%

a. accepts data

Input

b. processes data Processingc. produces output Outputd. stores results Storage

Input (Data)

Input is the raw information entered into a computer from the input devices. It is the collection ofletters# numbers# images etc.

Process

&rocess is the operation of data as per given instruction. It is totally internal process of the

computer system.

Output

Output is the processed data given by computer after data processing. Output is also called as

esult. 'e can save these results in the storage devices for the future use.

!"#antages o$ computers

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0. %igh spee" Computers have the ability to perform routine tasks at a greater speed than

human beings. 1hey can perform millions of calculations in seconds.

2. !ccurac&Computers are used to perform tasks in a way that ensures accuracy.

3. Storage Computers can store large amount of information. !ny item of data or any

instruction stored in the memory can be retrieved by the computer at lightning

speeds.

4. !utomation Computers can be instructed to perform comple5 tasks automatically (which

Increases the productivity).

6. Di'igence Computers can perform the same task repeatedly + with the same without getting

tired.

7. ersati'it& Computers are fle5ible to perform both simple and comple5 tasks.

8. Cost e$$ecti#eness Computers reduce the amount of paper work and human effort#

thereby reducing costs.

OR!*I+!TIO* O, COMPUTER (OR) ,U*CTIO*!- U*ITS O, !

COMPUTER (OR) .-OC/ DI!R!M O, ! COMPUTER

! computer system has the following main components%

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0) Input unit

2) Central &rocessing 9nit (C&9).

3) Output unit.

Input unit%Input unit accepts coded information from human operators through electromechanical

devices such as the 0e&oar". 1he information received is either stored in the memory for later

reference or immediately used by the !rithmetic and ,ogic circuitry to perform the desired

operation. :inally the result is sent back to the outside through the output unit.

*5amples% keyboard# ;oy stick# track ball# mouse (pointing devices)# scanner etc.

Central &rocessing 9nit%Central &rocessing 9nit (C&9) is the main component or ual to and greater than. !ll calculations and comparisons are performed in arithmetic logic

unit.

Contro' Unit

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1he control unit is responsible for controlling the transfer of data and instructions among

other units of a computer. It is considered as the


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Memor& Unit

"emory unit is that component of a computer system which is used to store data#

instructions and information before and after the processing by !,9. It is actually a work area

within a computer where C&9 stores data and instructions. It is also known as a main memory or

primary or internal memory.

Output unit%

Output unit accept binary data from the computer and decodes it into original form and

supplies this result to the outside world. *.g. monitor# &rinter# /ideo terminals (provides both

input + output functions)# graphic displays etc

E*ER!TIO* O, COMPUTERS (%istor& o$ computers)

1he first electronic computer was designed and built at the 9niversity of &ennsylvania

based on vacuum tube technology. /acuum tubes were used to perform logic operations and to

store data. $enerations of computers has been divided into five according to the development of

technologies used to fabricate the processors# memories and IDO units.

I eneration 1345 6 55

II eneration 1355 6 75

III eneration 1375 6 85

I eneration 1385 6 93

eneration 1393 to present

,irst eneration (1345 6 55)

0. In this generation


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?. 0stgeneration computers are called%

(*I!C - *lectronic umerical Integrator and Calculator

*S!C E *lectronic elay Storage !utomatic Calculator

*/!CE*lectronic iscrete /ariable !utomatic computer

9I/!C E 9niversal !utomatic Computer I" 8A0)

Secon" eneration (1355 6 75)

0. In this generation


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Thir" eneration (1375 6 85)

0. In this generation uery systems# automatic industrial

control etc.0A. In 3rdgeneration computers are called% (System 37A "ainframe from I"# &&-? "ini

Computer from igital *>uipment

Corporation).

,ourth eneration (1385 6 93)

0. /,SI (/ery ,arge Scale Integrated Circuits) was used for basic operations.

2. /,SI design with 1ens of thousands of transistors can be placed in a single chip.

3. It consumes less power with high performance# lower cost and very compact and muchincrease in the speed of operation.

4. In this time Semiconductor memory chips were used as the main memory.

6. C1 screen# laser + ink Bet printers# scanners are also developed.

7. 1he Secondary storage memories# i.e. hard disks# :loppy disks + magnetic tapes were

used for backup memory.

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8. 1he &arallelism# pipelining cache memory and virtual memory were applied in a better

way.

?. In this generation ,! and '!S were developed used for desktop work stations

interconnected.

F. C language# 9ni5 OS# and $raphical 9ser Interface was introduced.

0A. In 4thgeneration computers are called% (IntelGs ?A??#?A2?7#?A3?7#?A4?7 ..#

"otorolaGs 7?AAA# 7?A3A# 7?A4A#

!pple II# C!H ID2DD"& etc).

,i$th eneration (1393 to at present)

0. Introduced 9,SI (9ltra ,arge Scale Integration) technology is developed for operations.

:or e5ample IntelGs &entium 4 microprocessor contains 66 million transistors millions of

components on a single IC chip.

2. In this generation also developed Superscalar processors# /ector processors# SI"

processors# 32 bit micro controllers and embedded processors# igital Signal &rocessors

(S&) etc.

3. 1he ObBect oriented language like ;!/! for developed internet programming and new

operating systems 'indows F6DF?D&DJ# ,I9# etc were developed.

4. 1he Computers based on artificial intelligence and &ortable note book computers

introduced in this time.6. Computers are used base on e5tensive parallel processing# multiple pipelines# multiple

processors# massive parallel machines and e5tensively distributed system connected by

communication networks etc.

7. In this time also Introduced 'orld 'ide 'eb and other e5isting applications like e-mail#

e-Commerce# /irtual librariesDClassrooms# multimedia applications etc.

8. "emory chips up to 0 $# hard disk drives up to 0?A $ and optical disks up to 28 $

are available (still the capacity is increasing). Storage technology and advanced large

main memory and disk storage available.

?. 1he Kuantum mechanism and nanotechnology will radically change the phase and

variation of computers.

F. In this generation computers are called% (I" notebooks# &entium &Cs-&entium 0D2D3D4D

ual coreDKuad core# S9 work stations# Origin 2AAA# &!!" 0AAAA# I" S&D2).

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COMPUTERS ,OR I*DIIDU!- USERS (or) T:PES O, COMPUTERS (or)

C-!SSI,IC!TIO*S O, COMPUTERS (or) COMPUTERS ,OR OR!*I+!TIO*S%

"ost computers arc meant to be used by only one person at a time. Such computers are

often shared by several people (such as those in your schoolGs computer lab)# but only one user

can work with the machine at any given moment.

1he primary types of computers in this category are%

12 Main$rame Computers

;2 Minicomputers

uently need to use the same data. In a traditional mainframe

environment# each user accesses the mainframeGs resources through a device called atermina'.

1here are two kinds of terminals#

! "um termina'does not process or store data@ it is simply an inputDoutput (IDO) device

that functions as a window into a computer located somewhere else. !n inte''igent termina'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 themainframe. E=amp'es of mainframe computers are% I" 3AAA series# urroughs 8FAA#

9nivac 00?A# and *C.

"inicomputers%

It was first released in the 0F7As. "inicomputers are small sie compared to other

computers of the day. 1he capabilities of a minicomputer are somewhere between those of

mainframes and personal computers. :or this reason# minicomputers are often called


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Super computers

Supercomputers are the most powerful computers made# and physically they are some of

the largest. 1hese systems can process huge amounts of data# and the fastest. Super computers

can perform more than one trillion calculations per second. Some supercomputers can contains

thousands of processors. Supercomputers are ideal for handling large and highly comple5

problems that re>uire e5treme calculating power. :or e5ample# supercomputers have long been

used in the mapping of the human genome# forecasting weather# and modeling comple5

processes like nuclear fission. *5amples of super computers are C!H esearch %- C!H-0 +

C!H-2# :uBitsu (/&2AAA)# itachi (S?2A)# *C (S2A)# &!!" 0AAAA by C-!C# !nupam

by !C# &!C* Series by O.

"icro Computers%

1hey are designed to be used by only one person at a time. ! microcomputer uses a

microprocessor as its central &rocessing 9nit (C&9). "icrocomputers are tiny computers that

can be different in sie from a single chip to the sie of a desktop model. ItGs having Small to

medium data storage capacities 6AA" E 2$.1he common e5amples of microcomputers are

chips used in washing machines# 1/s# Cars and ote bookD&ersonal computers.

*5amples of super computers are% I" &C# &SD2 and !pple "acintosh

1his can be divided based on sies as fallows%

a2 esktop computers.

2 'orkstations.

c2 otebook computers.

"2 1ablet computers.

e2 andheld computers.

$2 Smart phones.

Des0top computers

1he desktop computer is a &ersonal Compute. 1hat is designed to sit on (or under) a desk

or table. 1hese are the systems you sec all around you# in schools# homes# and offices. esktop

computers are more powerful and are used for an amaing array of tasks or Bobs with greater

easy and efficiency. ut they can be also used to communicate# produce music# edit photographs

and videos# play sophisticated games. ut it was much more used by everyone from preschoolers

(,.L.$) to nuclear physicists@ desktop computers are indispensable for learning# work# and play.

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Wor0stations

! workstation is a specialied@ single-user computer that typically has more power and

features than a standard desktop &C. 1hese machines are popular among scientists# engineers#

and animators who need a system with greater-than-average speed and the power to perform

sophisticated tasks. 'orkstations often have large# high-resolution monitors and accelerated

graphics handling capabilities# making them suitable for advanced architectural or engineering

design# modeling# animation# and video editing.

*oteoo0 Computers

otebooks computers are appro5imate the shape of notebook and easily fit inside a

briefcase. ecause people fre>uently set these computers on their lap# they are also called laptop

computers. otebook computers can operate on alternating current or special batteries. 1hese

computers is generally weigh less than eight pounds# and some of weigh less than three pounds

based on a thin monitor and a keyboard and easy storage. otebooks are fully functional

microcomputers@ the people who use them need the power of a full-sie desktop computer.

Ta'et PCs

1he tablet &C is the newest development in portable# full-featured computers). 1ablet

&Cs offer all the functionality of a notebook &C# but they are lighter and can accept input from a

special pen called a st&'us or a "igita' pen. 1hat is used to tap or write directly on the screen.

"any tablet &Cs also have a built-in microphone and special software that accepts input from the

userMs voice. ! few models even have a fold-out keyboard# so they can be transformed into a

standard notebook &C. 1ablet &Cs run specialied versions of standard programs and can be

connected to a network. Some models also can be connected to a keyboard and a full sie

monitor.

%an"he'" PCs

andheld personal computers are computing devices small enough to fit in your hand. !

popular type of handheld computer is the persona' "igita' assistant(&!). ! &! is no larger

than a small appointment book and is normally used for special applications# such as taking

notes# displaying telephone numbers and addresses# and keeping track of dates or agendas. "any

&!Gs can be connected to larger computers to e5change data. "ost &!s come with a pen that

lets the user write on the screen. Some handheld computers feature tiny built-in keyboards or

microphones that allow voice input.

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Smart Phones

Some cellular phones double as miniature &Cs. ecause these phones offer advanced

features not typically found in cellular phones# they are sometimes called smart phones. 1hese

features can include 'eb and c-mail access# special software such as personal organiers# or

special hardware such as digital cameras or music players. Some models even break in half to

reveal a miniature keyboard.

'!1 !* 1* II1I!, &!1S O: ! CO"&91* SHS1*"N

Computers come in many varieties# from the tiny computers built into household

appliances# to the astounding supercomputers that have helped scientists map the human genome.

ut no matter how big it is or how it is used# every computer is part of a system.

! complete computer system consists of four parts%

12 %ar"are

;2 So$tare


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:or e5ample% OS (isk Operating System)# !SIC# COO,# dase# !ccounting Software etc.

ata%

ata consist of individual facts# figures or pieces of information that by themselves may

not make much sense to a person. ! computerGs primary Bob is to process these tiny pieces of

data in various ways# converting them into useful information.

9sers%

&eople are the computer operators# also known as users. It can be argued that some

computer systems are complete without a personGs involvement@ however# no computer is totally

autonomous. *ven if a computer can do its Bob without a person sitting in front of it# people still

design# build# program# and repair computer systems. 1his lack of autonomy is especially true of

personal computer systems# which arc the focus of this book and are designed specifically for use

by people.

'!1 !* 1*


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/E:.O!RD

/E: .O!RD

1. Leyboard is the main input device of a computer (similar to a typewriter).

;. It contains three types of keys a'phanumeric 0e&s2

Mo"i$ier 0e&s2

*umeric 0e&s2

Specia' 0e&s2

,unction 0e&s.


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The !'phanumeric /e&s

1he alphanumeric keys are looks like a typewriterMs keys. 1hose are arranged the same

way on almost every keyboard. Sometimes this common arrangement is called the K'*1H

layout. ecause the first si5 keys on the top row of letters are K# '# *# # 1# and H.

!long with the keys that produce letters and numbers. 1he alphanumeric key group

includes four keys having specific functions. 1he 1!# C!&S ,OCL# !CLS&!C*# and

*1* keys are described !lphanumeric keys. 1hat are used to type all alphabets# numbers and

special symbols like # P# Q# ! etc.

The Mo"i$ier /e&s

1he SI:1# !,1 (!lternate)# and C1, (Control) keys are called modifier keys.

because they modify the input of other keys. In other words# if you hold down a modifier key

while pressing another key# then you are changing the second keyMs input in some way.

:or e5ample# if you press the ; key# you input a small letter. ut if you hold down the

SI:1 key while pressing the ; key# you input a capital. "odifier keys arc e5tremely useful

because they give all other keys multiple capabilities.

The *umeric 0e&s

1he numeric keypad is usually located on the right side of the keyboard. 1he numeric

keypad looks like a calculatorMs keypad# with its 0A digits (A to F) mathematical operators (R# -# #

and D). 1he numeric keypad also features a 9" ,OCL key# which forces the numeric keys to

input numbers. 'hen 9" ,OCL is deactivated# the numeric keypadMs keys perform cursor

movement control and other functions.

The ,unction /e&s

1he :unction keys such as T:lU# T:2U# T:3UJJ. Tf02U.are used to give special

commands depending upon the software used. 1hey are usually arranged in a row along the top

of the keyboard. 1hey allow you to input commands without typing long strings of characters or

navigating menus or dialog bo5es. *ach function keyMs purpose depends on the program you are

using.

:or e5ample# in most programs# :l is the help key. 'hen you press it# a special window

appears to display information about the program you are using. "ost I"-compatible

keyboards have 02 function keys. "any programs use function keys along with modifier keys to

give the function keys more capabilities.

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(&OI1I$ */IC*S)

"O9S*%

! mouse is an input device that you can move around on a flat surface (usually on a desk

or keyboard tray) and controls the pointer. 1he pointer (also called the mouse pointer) is an on-screen obBect# usually an arrow# that is used to select te5t@ access menus@ and interact with

programs# files# or data that appear on the screen. :igure 2!.00 shows an e5ample of a pointer in

a program window.

1he mouse can mainly divided into two types% 12 The mechanica' mouse

;2 The optica' mouse.

1he "*C!IC!, "O9S* is the most common type of pointing device. !

mechanical mouse contains a small rubber ball that can see through a hole in the bottom of the

mouseMs case. 1he ball rolls inside the case when you move the mouse around on a flat surface.

So Inside the mouse# the ro''ersand sensorssend signals to the computer# telling it the "istance@

"irection@ an" spee"of the ballMs motions. 1he computer uses this data to position the mouse

pointer on the screen.

1he O&1IC!, "O9S* is a non-mechanical mouse. 1his type of mouse emits a eam o$

'ightfrom its underside. It uses the lightMs reflection to Budge the "istance@ "irection@ an" spee"

o$ its tra#e'.

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Uses o$ Mouse

Hou use a mouse to move the pointer to a location on the screen# a process called

pointing. *verything you do with a mouse is accomplished by combining pointing with four

techni>ues%

a. Clicking

b. ouble-clicking

c. ragging

d. ight-clicking

C'ic0ing is used for click an item with the mouse and move the pointer to the item on the

screen. 'hen the pointer touches the obBect# >uickly press and release the primary mouse button

once. Clicking or single clicking is the most important mouse action. 1o select any obBect on the

screen# such as a menu# command# or button# you click it.

Dou'eAc'ic0ing means pointing to the item with the mouse pointer and then pressing and

releasing the mouse button twice in rapid succession. ouble-clicking is primarily used with

desktop obBects such as icons. :or e5ample# you can double-click a programMs icon to launch the

program.

Draggingan item means positioning the mouse pointer over the item# pressing the left mouse

button# and holding it down as you move the mouse. !s you move the pointer# the item is

ue is also called "ragAan"A"rop e"iting# or Bust "rags an" "rop.

RightAc'ic0ingmeans pointing to an item on the screen# then pressing and releasing the right

mouse button. ight-clicking usually opens a shortcut menu that contains commands and options

that pertain to the item to which you are pointing.

SC!*%

! scanner is widely used in esktop &ublishing (1&) applications. It is used for

digitiing images such as photographs# forms# documents etc. 1here are many types of scanners

which can also read te5t by converting them to digital code. 1he scanners are very useful for

converting the typed pages into word processing files. $raphic scanners convert a printed image

into video image without converting it to digital code.V

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;OHS1ICL%

;oystick is also a pointing device used to move cursor position on a monitor screen. It is a

stick having a spherica' a''at its both lower and upper ends. 1he lower spherical ball moves in

a soc0et. It can be moved in all the four directions. 1he function of a Boystick is similar to that of

a mouse. It is mainly used in Computer-!ided esigning (C!) and playing computer games.

O&1IC!, "!L *!* (O")%

Optical "ark eader (O") is a special type of optical scanner used to recognie the

type of mar0 ma"e & pen or penci'. It is especially used for checking answer sheets of

e5amination having multiple-choice >uestions. 1he answer sheet contains special marks such as

sBuares or u'es. 1he student fills in these s>uares with soft pencil or ink to indicate the

correct choice. 1he O" detects these marks and sends corresponding signals to the processor.

If a mark is present# the amount of reflected light is reduced. O" detects the presence of mark

for each and every answer. 1hese are widely used for almost all competitive e5aminations

having obBective type >uestions.

! CO* *!*%

ar code reader is an optical scanner used for reading bar coded data (data in the form of

light and dark lines). 1he bar coded data consists of a number of bars of varying thickness and

spacing between them. 1he bar code reader reads the bar coded data and converts it into

electrical pulses which are then processed by computer. ar coded data is generally used in

labeling goods# numbering the books# or encoding I or !Dc numbers.

O&1IC!, C!!C1* *!* (OC)%

Optical Character eader (OCR) is an optical scanner which is capable of identifying

!'phanumeric characterstyped or printed on paper using an OC font. 1he te5t which is to be

scanned by a low fre>uency light source. 1he dark areas on the te5t collect the light while light

areas reflect it. 1he photocells of OC device receive this reflected light and provide binary data

corresponding to dark and light areas. OC devices are used for large volume applications like

reading of passenger tickets# computer printed bills of credit card companies and XI& codes in

postal services.

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"!$*1IC IL C!!C1* *CO$I1IO ("IC)%


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'!1 !* 1* O91&91 */IC*S%

("onitors#printers and plotters)

"OI1OS%

1he monitor is the most commonly used output device on most personal computer

systems. 'hen you are typing a letter# copying files# or surfing the Internet that are looking at

your monitor. 1hey want to see whether the image is crisp and clear and how well graphics are

displayed on the monitor.

1wo important hardware devices determine the >uality of the image you see on any

monitor% (0) 1he monitor (2) 1he video controller. Color monitors can display between 07 colors

and 07 million colors. 1oday# most new monitors display in color. "any color monitors can be

set to work in monochrome or grayscale mode.

1he monitors can be divided into to types based on color%

Monochrome monitors It can display only one color that is black. (Such as green#

amber# or white) against a contrasting background. 1hese monitors are used for only displays

. 'here the user does not need to see color graphics.

ra&sca'e monitors It can display various intensities of gray from a very little gray to

black against a white or off-white background. !nd these are essentially a type of monochrome

monitor. $rayscale flat panel displays are used in low-end portable systems.

1here are two types of monitors are used with &Cs. ! catho"e ra& tue (CRT)

! $'atApane' "isp'a&

1)2 ! catho"e ra& tue (CRT)

0. 1he cathode ray tube (C1) monitor comes with most desktop computers.

2. It looks a television screen. 1his type of monitor uses a large vacuum tube for display2

3. 1he C1 monitor works from back o f a monitorMs housing is an e'ectron gun.

4. 1he gun shoots a beam of electrons through a magnetic coil called a &o0e. 1his aims the

beam at the front of the monitor.

6. 1he back of the monitorGs screen is coated with phosphors# chemicals that glow when

they are struck by the electron beam.

7. 1he screenGs phosphor coating is organied into a gri" o $ "ots.

8. 1he smallest number of phosphor dots that the gun can focus on is called a pi=e'2

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?. 1he &i5el is a contraction of the term picture element. *ach pi5el has a uni>ue address#

which the computer uses to locate the pi5el and control its appearance. Some electron

guns can focus on pi5els as small as a single phosphor dot.

F. 1he electron gun does not Bust focus on a spot and shoot electrons at it.

0A. It systematically aims at every pi5el on the screen# starting at the top left corner and

scanning to the right edge. 1hen it drops down a tiny distance and scans another line.

00. ! C1 monitor contains a shadow mask# it is a fine mesh made of metal# fitted to the

shape and sie of the screen.

02. 1he holes in the shadow maskGs mesh are used to align the electron beams# to ensure that

they strike precisely the correct phosphor dot. In most shadow masks# these holes are

arranged in triangles. C1 monitors have long been the standard for use with desktop

computers because they provide a bright# dear picture at a relatively low cost.

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;)2 ! $'atApane' "isp'a&

1he :lat-panel monitors have been used primarily on portable computers. a new

generation of large# high-resolution# flat-panel displays is gaining popularity among users of

desktop systems. 1hese new monitors provide the same viewable area as C1 monitors# but they

take up less desk space and run cooler than traditional C1 monitors.

1here are several types of flat-panel monitors%

I)2 -iBui" cr&sta' "isp'a& (-CD)

1he ,C monitor creates images with a special kind of li>uid crystal. 1hat is normally

transparent but becomes opa>ue when charged with electricity. ,C monitors is that their

images can be difficult to see in bright light. :or this reason# laptop computer users often look for

shady places to sit when working outdoors or near windows.

! bigger disadvantage of ,C monitor is their limited viewing angle. 1hat is the angle

from which the displayMs image can be viewed clearly. Hou can sec the image clearly even when

standing at an angle to the screen with most C1 monitors. In ,C monitors the viewing angle

shrinks and as you increase your angle to the screen# the image becomes fuy >uickly.

II)2 The passi#e matri= -CD

The passi#e matri= -CDworks based on transistors for each row and each column of

pi5els. ! grid that defines the location of each pi5el. 1he color displayed by a pi5el is

determined by the electricity coming from the transistors at the end of the row and the top of the

column. !nother disadvantage is that they donGt uickly. If you move

the pointer too >uickly# it seems to disappear an effect known as submarining. !nimated

graphics can appear blurry on a passive matri5 monitor.

Other T&pes o$ Monitors

epending upon the resolution# monitors can be classified as follows%

a2 C!%(Color Graphics Adapter):

It is a circuit board introduced by I" and the first graphics standard for the I" &C.

'ith a C$! monitor# it is harder to read than with a monochrome monitor# because the C$!

(32A 2AA) has much fewer pi5els than the monochrome monitor (74A 36A). It supports 4

colors.

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2 E!%(Enhanced Graphics Adapter)%

*$! is a video display standard that has a resolution of 74A by 36A pi5els and supports

07 colors. *$! supports previous display modes and re>uires a new monitor.

c2 !% (Video Graphics Array) t

This is a video display standard that provides medium to high resolution. In a te5t mode#

the resolution of this board is 82A by 4AA pi5els. It supports 07 colors with a higher

resolution of 74A by 4?A pi5els and 267 colors with 32A 2AA pi5els.

"2 Super !%

1his is a very high resolution standard that displays up to 76#637 colors. Super !can

support 07.? million colors at ?AA by 7AA pi5els and 267 colors at 0A24 by 87? pi5els. !

high-priced super /$! allows 02?A by 0A24 pi5els. ,arger monitors (08W or 20W and larger)

with a high resolution of 07AA by 02?A pi5els are available.VESA(Video Electronics

Standards Association) has set a standard for super /$!.

PRI*TERS

! printer is an output device that produces a hard copyof data. 1he resolution of printer

output is e5pressed as &I. &rinters can produce te5t and images on paper. &aper can be eitherseparate sheets such as !4 !6 !3 etc. or they may be able to print on continuous (fanfold) paper

that feed through the machine.

Dais&AWhee'@ Chain Printer@ Drum printer

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1) Impact Printers

In this hammers or pins strike against a ribbon and paper to print the te5t. 1his

mechanism is known as electro-mechanical mechanism. 1hey are of two types.

(i) Character Printer

(ii) Dot matri= printer

(iii) -ine Printer

(i#) Dais&AWhee' Printer

(#) Drum printer

(vi) Chain Printer

Character Printer%

It prints only one character at a time. It has relatively slower speed. *.g. Of them are ot

matri5 printers.

Dot Matri= Printer%

ot-matri5 printers print about 4A


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Drum printer

In which each complete set of characters for each print position on a line is on a

continuously rotating drum behind an inked ribbon. In front of the ribbon identical characterGs

are printed continues with a ribbon at all re>uired position on a line.

Chain Printer

It is the character printer. 1he print element in a chain printer is a meta''ic an"or chain

containing the embossed characters that rotates horionta''&in front of paper. ! complete chain

consists of the five sections@ each section consists of 4? characters. !s the print chain rotates#

properly timed print hammers strike the paper along with linked ribbon# against the proper

character on the chain as it passes. Chain printers are one of the fastest impact printers that can

produce up to 4AA to 26AA characters per second. Chain &rinter also called band printers# contain

characters on a rotation band. Speeds of up to 3AAA lines a minute may be possible with these

machines.

;) *onAImpact Printers%

1here printers use non-Impact technology such as ink-Bet or laser technology. 1here

printers provide better >uality of OD& at higher speed. on-impact printers# used almost

everywhere now# are faster and >uieter than impact printers because they have fewer moving

parts. on-impact printers form characters and images without direct physical contact between

the printing mechanism and the paper.

1hese printers are of two types% 0. In0Aet Printer

;2 -aser Printer

In0Aet Printer

Ink-Bet printers also print images ith 'itt'e "ots. In0AFet printers spra& sma''@

e'ectrica''& charge" "rop'ets o$ in0from four noles through holes in a matri5 at high speed

onto paper. Ink-Bet printers can print in co'ourand are >uieter and much less e5pensive than a

colour laser printer. owever# they are slower and print in a somewhat lower reso'ution (


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1he another type of ink-Bet technology is the u'eAFet printer# which use miniature

heating elements to force specially formulated inks through print heads with 1;9 tin& no'es.

1he mu'tip'e no'es print $ine images at high spee"s. 1his technology is commonly used in

portable printers.

-aser Printer

,aser &rinter is a type of printer that utilies a laser beam to produce an image on a drum.

1he light of the laser alters the electrical charge on the drum wherever it hits. 1he drum is then

rolled through a reservoir of toner# which is picked up by the charged portions of the drum.

:inally# the toner is transferred to the paper through a combination of heat and pressure. 1his is

also the way copy machines work. ecause an entire page is transmitted to a drum before the

toner is applied# laser printers are sometimes called page printers.

1here are two other types of page printers that fall under the category of laser printers

even though they do not use lasers at all. One uses an array of ,*s to e5pose the drum and 1he

other uses ,Cs.

Once the drum is charged# however# they both operate like a real laser printer. One of the

chief characteristics of laser printers is their resolution E how many dots per inch (dpi) they lay

down. 1he available resolutions range from 3AA dpi at the low end to 0#2AA dpi at the high end.

P-OTTERS

! plotter is a computer printing device for printing #ector graphics. In previous days#

plotters were widely used in computer-aided design applications. 1hough they have generally

been replaced with wide-format conventional printers. It is now common place to refer to such

wide-format printers as Wplotters#W

&lotter is a device that "ras pictureson paper based on commands from a computer.

&lotters different $rom printersin that they draw lines using a pen2!s a result# they can producecontinuous lines# whereas printers can only simulate lines by printing a closely spaced series of

dots. "ulti colour plotters use different-collared pens to draw different colours.

In general# plotters are considerably more e5pensive than printers. 1hey are used in

engineering applications where precision is mandatory.

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&OC*SSI$ !1!

O' *&*S*1 !1! CO"&91*SN

1he data can be represented in computers in different ways. 1hey are%

1) umber system( inary number# and ecimal number )

;) its and bytes.


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;2 .ITS !*D .:TES

! bit is the smallest possible unit of data a computer can recognie or use. ! binary digit

is a single numeral in a binary number. *ach 0 and A in the number below is a binary digit% E 0 A

A 0 A 0 A 0. 1he term


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ue

character and symbol in the world# including the vast Chinese# Lorean# and ;apanese character

sets and t hose found in known classical and historical te5ts.

In addition to world letters# special mathematical and scientific symbols are represented in

9nicode. One maBor advantage that 9nicode has over other te5t code systems is its compatibility

with !SCII codes. he first 267 codes in 9nicode are identical to the 267 codes used by the

!SCII and *5tended !SCII systems.

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O' &OC*SS 1* !1! I CO"&91*N

Processing is the thin0ingthat the computer does - the calculations# comparisons# and

decisions. Computers process very large amounts of data because they can communicate the data

much more >uickly than a person. "ost data processing is mundane# and would be prone to

human error if not processed by computer.

1he processing can be done in computer at toplaces. 1hey are

CPU

MEMOR:

12 CPU ( Centra' Processing Unit )

1he CPU# or Centra' Processing Unit# is the part of the computer where work gets done.

In most computers# there is one processing chip. C&9 performance is often measured in mi''ions

o$ instructions per secon" ("I&S). ewer C&9s can be measured in i''ions o$ instructions

per secon" (I&S). C&9 has two parts called CO1O, 9I1 and !,9.

Contro' Unit

1he control unit is responsible for controlling the transfer of data and instructions among

other units of a computer. It is considered as the


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!rithmetic 'ogic unit (!-U)

!,9 stands for !rithmeticD,ogic 9nit. 1his is the part that e5ecutes the computerMs

commands. ! command must be either a basic arithmetic operation or one of the 'ogica'

comparisons.

Operations Per$orme" & the !rithmetic -ogic Unit

(!rithmetic Operations) (-ogica' Operations)

R !dd Z# [ e>ual to# not e>ual to

- Subtract U# \U greater than# not greater than

"ultiply T# \ T (,ess than# not less than

P ivide

ise by a power

1he !-Uincludes a group of registers with high-speed memory locations built directly

into the C&9 that are used to hold the data currently being processed. Hou can think of the

register as a scratchpad. 1he !,9 w ill use the register to hold the data currently being used for a

calculation.

:or the data processing and e5ecution C&9 can take four steps%

12 ,etching%

efore the C&9 can e5ecute an instruction# the control unit must retrieve (or fetch) a

command or data from the computerGs memory.

;. Deco"ing

efore a command can be e5ecuted# the control unit must break down (or decode) the

command into instruct ions that correspond to those in the C&9Gs instruction set.


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2. "emory%

1he C&9 contains the basic instructions needed to operate the computer@ but it cannot

store entire programs or large set s of data permanently. 1he C&9 needs to have millions (or

even trillions) of bytes of space where it can >uickly read or write programs and data while they

are being used. 1his area is called memory# and it consists of chips either on the motherboard or

on a small circuit board attached to the motherboard.

1here are three types of built-in memory% permanent@ nonApermanent an" $'ash memor&2

I) Permanent or *onA#o'ati'e Memor&

Some memory chips contain or stores the data even when the computer is turned off. 1his

type of permanent memory is called non#o'ati'e21he data in t these chip is only read and used

but it can not changed the data. so the memory is called read only memory (RO M )2 1he O"

contains a set of start-up instructions called the


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'!1 IS .USN '!1 !* 1* I::**1 1H&*S O: 9SGSN

The .us

1here are two main b uses in a computer%


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The !""ress .us

1he address bus is a set o$ iressimilar to the data bus. 1he address bus connects only

the C&9 and !" and carries only memory addresses. emember each byte in !" is

associated with a numer@which is its memory address.

Categories of busGs%

12 IS! us

The In"ustr& Stan"ar" !rchitecture (IS!)bus. It is a 17 Aitdata bus. It became

the de facto industry standard on its release in the mid-0F?As and is still used in many computers

to attach slower devices (such as modems and input devices) to the C&9.

;2 The -oca' us

1he -oca' uswas developed to attach faster devices to the C&9. ! local bus is an

internal system bus that runs between components on the motherboard. "ost system buses uses

some type of local bus technology today and are coupled with one or more kinds of e5pansion

bus.


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cards that support 3- and full- "otherboard motion video. 'hile !$& improves graphics

performance# it cannot be used with all &Cs.

52 US. us

1he Uni#ersa' Seria' .us(9S) is a relatively new bus found on all modern machines.

9nlike the &CI and !$ 9S is a hot swappable bus. 1his means that a user can connect then

disconnect a 9S device without affecting the machine. 9S supports up to 028 devices

connected in either a "ais& chainor hulayout.

72 IEEE 1


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MEMORY

'!1 IS "*"OH (O) S1O!$* */IC*N

(Or)'!1 !* 1* I::**1 1H&*S O: S1O!$* */IC*SN

(Or)*&,!I !O91 I::**1 1H&*S O: "*"OHSN

&rimary memory devices%

De$inition "emory or storage capacity is one of the important components of a computer.

!ny storage unit of a computer system is classified on the basis of the following criteria%

0. !ccess time% 1his is the time re>uired to locate and retrieve stored data from the

storage unit in response to program instructions.

2. Storage capacit&% It is the amount of data that can be stored in the storage unit.

3. Cost per it o$ storage.

1he computer stores a character in the storage cells with binary (A#0) mechanism.

1hus the basic unit of memory is a bit (binary digit A# 0). 1o store a character in a computer

re>uires ? bits or 0 byte. 1his is called the word length of the storage unit.

1he different units of measurement are

? its Z 0 yte

20A(or) 0A24 ytes Z 0 Lilo yte (L)

20A L (or) 0A24 L Z 0 "ega yte (")

20A" (or) 0A24 " Z 0 $ega yte ($)

20A $ ( or) 0A24 $ Z 0 1erra yte (1)

1here are mainly two types of memories% 12Primar& memor& (main memor&)

;2 Secon"ar& memor&

12 Primar& memor& (main memor&)

a. &rimary memory is the one of the main memory of the computer.

b. &rimary memory is accessible directly by the central processing unit.

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c. In &rimary memory the contents or data is lost as soon as if the computer is switched off.

Hou can store and retrieve data much faster with primary memory.

d. ut the &rimary memory is more e5pensive and sie is less.

e. It can stores the necessary programs of the system software for e5ecute user programs.

1he main memory or primary memory can be divided into two types%

a. R!M (andom !ccess "emory)

b. ROM (ead Only "emory).

Ran"om !ccess Memor& (R!M)

a) R!M stands for Ran"om !ccess Memor&2

) It is possible to select randomly and use any location of the memory directly store and

retrieve data.

c) It is also called read or write memory.

") 1he data or instructions can be stored in the !" is temporarily.

e) In !" data is disappears as soon as the power to the computer is switched off.

$) So now we can say that !" is #o'ati'ememory.

g) 1his can be divided into 2 types% S1!1IC !" and H!"IC !".

h) In the static ram the data or instruction can stores only as long as the power supply is O.

i) ut in the dynamic ram the information or data can be stored very short time and it

refreshed periodically.

Rea" On'& Memor& (ROM)

a) ROM stands for Rea" on'& Memor&2

) 1his can store the programs and data is permanently.

c) 1he O" stores some standard processing programs supplied by the manufacturers to

operate the personal computer.

") 1he O" can only be rea"by the C&9 but it cannot be changed or write any data.

e) It does not loose their content# data or instructions if the power supply is failure or supply

off.

$) O" also called as nonA#o'ati'ememory.

g) 1his can be divided into 3 types% PROM@ EPROM@ EEPROM an" ,-!S% ROM

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PROM%

PROM(&rogrammable ead Only "emory) memories were developed at the end of the

8As by a company called HTexas Instruments21hese memories are chips comprising thousands

of fuses or diodes that can be urntusing a device called a


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JSECO*D!R: STOR!E MEMOR: DEICES

1he secondary storage devices where used to overcome the problems with primary

memory. 1he Secondary "emory is also known as !u5iliary "emory or ackup "emory.

1hese are divided into two typesG magnetic memor&and optica' memories. 1here are so many

types of secondary memory devices%

12 ,'opp& Dis0s

;2 %ar" Dis0 (-oca' Dis0)


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(a)

(a)

(a)

(a)

(a)

(a) 60D4-inch floppy disk

;2 %ar" "is0

a) 1he hard disk can hold more information than the floppy disk and the retrieval of

information from hard disk is faster when compared to floppies or tapes.

b) ! hard disk is fi5ed inside the C&9 and its capacity ranges from 2A " onwards.

c) 1he hard disk is made up of a collection of discs (one below the other) known as


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JOPTIC!- MEMORIE DEICES

uality sound and graphics.

42 pen "ri#e(,'ash Dri#e)

It is a small# portable device that can be used to store# access and transfer data. ue to its

small sie# it is commonly called &en drive. It is also called 9S drive. 'e can read# write#

copy# delete# and move data from computer to pen drive or pen drive to computer. It comes in

various storage capacities of 2$# 4$# ?$ etc.

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1his device is plugged into the 9S port of the computer and the computer automatically

detects this device.

52 +ip "ri#e

! ip drive is a device for reading and writing data from removable storage evices called

Xip discs. Internal models typically take up a 2.6W drive bay (like a floppy disk drive). *5ternal

models are about the sie of a thick paperback book.

! ip disk is about the sie of 3 3.6W floppy disks stuck back to back# but has significantly

larger capacity. Xip disks are now# like floppy disks# obsolete. 1hey are physically larger# more

e5pensive# slower# store less data and are less reliable then 9S memory sticks.

72 Memor& car"s

! memor& car"or $'ash car"is an electronicflash memorydata storage deviceused for

storing digital information. 1hey are commonly used in many electronic devices#

includingdigital cameras#mobile phones# laptop computers# "&3 playersand video game

consoles.1hey are small# re-recordable# and able to retain data without power.

82 E=terna' %ar" "is0

! hard drivethat is outside of the computer casein its own enclosure. "ost e5ternal hard

drives support the I* interfaceand are slightly bigger than a hard drive itself. 'hen purchasing

an e5ternal hard drive you can buy a full e5ternal hard drive system that consists of both the hard

drive and the enclosure# or you can purchase Bust the enclosure to hold your own hard drive.

Solid-State Storage evices%

Solid state storage devices are uni>ue# among todayGs storage devices because they do not

use disks or tapes and have no moving parts. Solid-state storage is either magnetic or optical.

Instead# it relies on integrated circuits to hold data. Some solid-state storage devices are

nonvolatile% means they can retain their data even when the systemGs power is turned off. Others

are volatile% means they re>uire a constant supply of electricity or they will lose their data. 1he

deviceGs volatility depends on the type of memory circuits it uses.

1hey are divided into fallowing types%

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http://en.wikipedia.org/wiki/Flash_memoryhttp://en.wikipedia.org/wiki/Data_storage_devicehttp://en.wikipedia.org/wiki/Digital_camerahttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Digital_audio_playerhttp://en.wikipedia.org/wiki/Video_game_consolehttp://en.wikipedia.org/wiki/Video_game_consolehttp://www.webopedia.com/TERM/H/hard_disk_drive.htmlhttp://www.webopedia.com/TERM/T/tower_model.htmlhttp://www.webopedia.com/TERM/I/IDE_interface.htmlhttp://en.wikipedia.org/wiki/Flash_memoryhttp://en.wikipedia.org/wiki/Data_storage_devicehttp://en.wikipedia.org/wiki/Digital_camerahttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Digital_audio_playerhttp://en.wikipedia.org/wiki/Video_game_consolehttp://en.wikipedia.org/wiki/Video_game_consolehttp://www.webopedia.com/TERM/H/hard_disk_drive.htmlhttp://www.webopedia.com/TERM/T/tower_model.htmlhttp://www.webopedia.com/TERM/I/IDE_interface.html


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12 ,'ash Memor& ;2 Smart Car"s


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Software + languages

'hat is software + types of softwareGsN

SO:1'!*% Software is a program or set of instructions that causes the ardware to

function in a desired way.

1here are two types of software - s&stem so$tare an" app'icationK uti'it& so$tare2

!pp'ication so$tare

!pplication software allows end users to accomplish one or more specific (non-computer

related) tasks. 1ypical applications include industrial automation# business software# educational

software# medical software# databases# and computer games. usinesses are probably the biggest

users of application software# but almost every field of human activity now uses some form of

application software. It is used to automate all sorts of functions.

S&stem So$tare or uti'it& so$tare

System Software enables an application software to interact with the computer hardware.

System software is the ]backgroundG software that helps the computer to manage its internal

resources. 1he most important system software is the operating system. 1he system software

performs important tasks such as running the program# storing data# processing data etc.

'indows & is an e5ample of system software.

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'hat is language and what are the different types of languagesN

COMPUTER -!*U!ES

,anguage is the source of communication among human beings. ifferent

countriesDregions have different languages. Similarly# in order to communicate with the

computer user also needs to have a language that should be understood by the computer. :or this

purpose# different languages are developed for performing different types of work on the

computer. asically# languages are divided into two categories according to their interpretation.

12 -o -e#e' -anguages

,ow level computer languages are machine codes or close to it. Computer cannot

understand instructions given in high level languages or in *nglish. It can only understand and

e5ecute instructions given in the form of machine language i.e. language of A and 0.

1here are two types of low level languages%

Machine -anguage2

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!ssem'& -anguage

a) Machine -anguage

It is the lowest and most elementary level of &rogramming language and was the first

type of programming language to be developed. "achine ,anguage is basically the only

language which computer can understand. In fact# a manufacturer designs a computer to obey

Bust one ,anguage# its machine code# which is represented inside the computer by a String of

binary digits (bits) A and 0. 1he symbol A stands for the absence of *lectric pulse and 0 for the

presence of an electric pulse. Since a computer is Capable of recogniing electric signals#

therefore# it understands machine ,anguage.

!"#antages o$ Machine -anguage

i) It makes fast and efficient use of the computer.

ii) It re>uires no translator to translate the code i.e. directly understood by the computer

Disa"#antages o$ Machine -anguage

i) !ll operation codes have to be remembered

ii) !ll memory addresses have to be remembered.

iii) It is hard to amend or find errors in a program written

In the machine language

iv) 1hese languages are machine dependent i.e. a particular

) !ssem'& -anguage

It was developed to overcome some of the many inconveniences of machine language.

1his is another low level but a very important language in which operation codes and operands

are given in the form of alphanumeric symbols instead of AGs and lGs.

1hese alphanumeric symbols will be known as mnemonic codes and can have ma5imum

up to 6 letter combination e.g. ! for addition# S9 for subtraction# S1!1#,!*, etc.

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ecause of this feature it is also known as ]Symbolic &rogramming ,anguageG. 1his language is

also very difficult and needs a lot of practice to master it because very small

;2 %igh -e#e' -anguages

igh level computer languages give formats close to *nglish language and the purpose of

developing h igh level languages is to enable people to write programs easily and in their own

native language environment (*nglish). igh-level languages are basically symbolic languages

that use *nglish words andDor mathematical symbols rather than mnemonic codes. *ach

instruction in the high level language is translated into many machine language instructions thus

showing one-to-many translation

T&pes o$ %igh -e#e' -anguages

!SIC (eginners !ll &urpose Symbolic Instruction Code).

:O1!(,ormu'a Trans'ation)2

&,DI(Programming -anguage@ ersion 1)2

!,$O, (!lgorithmic ,anguage).

!&, (! Programming -anguage)2

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NETWORKSNETWORKS

0K) what is networkN

2K) what are the uses of networksN

3K) what are the different types of networksN

4K) what is topologyN

6K) what are the different types of topologiesN

What is netor0?

! network is a set of technologies including hardware# software# and media that can be

used to connect computers together# enabling them to communicate# e5change information# and

share information.

etworks allow many users to access shared data and programs almost instantly. 'hen

data and programs are stored on a network and are shared# individual users can substantially

reduce the need for programs on their own computers.

What are the uses o$ netor0s?

12 Simu'taneous !ccess

1here are moments in any business when several workers may need to u se the same data

at the same time. 'ithout a network that allows workers to share files# workers must keep

separate copies of data stored on different disks by each worker who accesses the data. 'hen the

data is modified on one computer# data on the other computers be comes outdated. It becomes

difficult to determine which copy of the data is the most current.

;2 Share" Periphera' De#ices

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1he ability to share peripheral devices (especially e5pensive ones such as high volume

laser printers# which can cost thousands of dollars) is one of the best reasons for small businesses

to set up a network. !lthough printers are more affordable than they were a few years ago# it is

still too e5pensive to provide every worker with a personal printer. !side from the cost of buying

multiple printers# maintenance contracts and supplies increase the total cost of ownership. 'hen

several people can share a printer on a network# printing becomes less e5pensive and easier to

manage.


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'hat are the different types of networksN

1here are three main types of networks%

12 -oca' area netor0s (-!*s)

;2 Wi"e area netor0s (W!*s)2


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area In contrast with

personal area networks

(&!s)# local area networks

(,!s)# campus area

networks (C!s)# or

metropolitan area

networks ("!s) which are usually limited to a room# building# campus or specific metropolitan

area (e.g.# a city) respectively. 1he largest and most well-known e5ample of a '! is the

Internet.

Metropo'itan area netor0s (M!*s)

1he metropolitan area network ("!) is a large scale network that connects multiple

corporate ,!s together. "!s usually are not owned by a single organiation@ their

communication devices and e>uipment are usually maintained by a group or single network

provider that sells its networking services to corporate customers. "!s often take the role of a

high speed network that allows for the sharing of regional resources. "!s also can provide a

shared connection to other networks using a '! link.

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What is topo'og&?

1O&O,O$H is the physical layout of the workstations# severs# gateways# hubs and

cabling# configuration of network# including the types of cable and connectivity devices used.

T&pes o$ topo'ogies

1here are 7 types of topologies and are as follows.

12 .us Topo'og&@

;2 Ring Topo'og&@


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Ring Topo'og&

0. In a ring network# every device has e5actly two neighbors for communication purposes.

2. !ll messages travel through a ring in the same direction.

3. ! failure in any cable or device breaks the loop and can take down the entire network.

4. 1o implement a ring network we use the 1oken ing technology

6. ! token# or small data packet# is continuously passed around the network. 'hen a device

needs to transmit# it reserves the token for the ne5t trip around# and then attaches its data

packet to it.

Star Topo'og&

0. In a star network# each node (file server# workstations# and peripherals) is connected to a

central device called a hu2

2. 1he hub takes a signal that comes from any node and passes it along to all the other nodes in

the network.

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3. ata on a star network passes through the hub# switch# or concentrator before continuing to its

destination.

4. 1he hub# switch# or concentrator manages and controls all functions of the network.

6. 1he star topology reduces the chance of network failure by connecting all of the systems to a

central node.

Mesh Topo'og&

0. In this topology# each node is connected to every other node in the network.

2. Implementing the mesh topology is e5pensive and difficult.

3. In this type of network# each node may send message to destination through multiple paths.

4. 'hile the data is traveling on the "esh etwork it is automatically configured to reach the

destination by taking the shortest route which means the least number of hops.

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Tree Topo'og&

0. ! tree topology (hierarchical topology) can be viewed as a collection of star networks

arranged in a hierarchy.

2. 1his tree has individual peripheral nodes which are re>uired to transmit to and receive from

one other only and are not re>uired to act as repeaters or regenerators.

3. 1he tree topology arranges links and nodes into distinct hierarchies in order to allow greater

control and easier troubleshooting.

4. 1his is particularly helpful for colleges# universities and schools so that each of the connect to

the big network in some way.

!1!

CO""9IC!1IOS

Data communication

ata communications are the e5change of data between two devices via some form of

transmission medium such as a wire cable. :or data communications to occur# the

communicating devices must be part of a communication system made up of a combination of

hardware (physical e>uipment) and software (programs).

1he effectiveness of a data communications system depends on four fundamental

characteristics% delivery# accuracy# timeliness# and Bitter.

12 De'i#er&. 1he system must deliver data to the correct destination. ata must be received by

the intended device or user and only by that device or user.

;2 !ccurac&. 1he system must deliver the data accurately. ata that have been altered in

transmission and left uncorrected are unusable.

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,ierAoptic ca'e

,ierAoptic ca'esare hollow cables that send data by pulses of light. :iber opticsallows for a much faster data transmission because of the capability of transmitting data at the

speed of light. "ost home computer users will never get the opportunity to work with fiber-optic

cables because almost all home networks use other cables or wireless connections to connect

their computers together. :iber-optic cables are most often used in corporate networks or world-

wide networks such as Internet backbones because of the capabilities of the cable.

Operating System

De$inition

!n Operating system is a program that controls the e5ecution of application programs

and acts as an interface between the user of a computer and the computer hardware.

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%istor& o$ Operating S&stem

,unctions o$ Operating S&stem

1oday most operating systems perform the following important functions%

0. Processor management% It manages the assignment of processor to different tasks being

&erformed by the computer system.

2. Memor& managementIt manages the allocation of main memory and other storage areas to

the system programsG as well as user programsG and data.

3. Input K Output management% It manages the co-ordination and assignment of different Input

and Output devices while one or more programs are

e5ecuted

.4. ,i'e management% It allows all files to be easily changed and modified through the use of

te5t editors or some other file manipulation routines.

6. Esta'ishment an" en$orcement o$ a priorit& s&stem % It determines and maintains the order

in which Bobs are to be e5ecuted in the computer system.

7. Interpretation of commands and instructions.

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8. :acilitates easy communication between the computer system and the computer operator.

T&pes o$ operating s&stem

12 .atch Operating S&stem

;2 Rea'ATime Operating S&stem(RTOS)

uipment.

!n 1OS typically has very little user-interface capability# and no end-user utilities#

since the system will be a Wsealed bo5W when delivered for use. ! very important part of an

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http://en.wikipedia.org/wiki/Embedded_systemhttp://en.wikipedia.org/wiki/Robothttp://en.wikipedia.org/wiki/Manufacturinghttp://en.wikipedia.org/wiki/Mass_productionhttp://en.wikipedia.org/wiki/Power_generationhttp://en.wikipedia.org/wiki/Power_generationhttp://en.wikipedia.org/wiki/Fabricationhttp://en.wikipedia.org/wiki/Refininghttp://en.wikipedia.org/wiki/Embedded_systemhttp://en.wikipedia.org/wiki/Robothttp://en.wikipedia.org/wiki/Manufacturinghttp://en.wikipedia.org/wiki/Mass_productionhttp://en.wikipedia.org/wiki/Power_generationhttp://en.wikipedia.org/wiki/Power_generationhttp://en.wikipedia.org/wiki/Fabricationhttp://en.wikipedia.org/wiki/Refining


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while it waits for IDOoperations to complete. owever# the term WmultitaskingW is more common

in this conte5t.

72 Distriute" Operating S&stem

In a distributed system# software and data maybe distributed around the system# programs

and files maybe stored on different storage devices which are located in different geographical

locations and maybe accessed from different computer terminals.

'hile we are mostly accustomed to seeing multi-tasking and multi-user operating

systems# the other operating systems are usually used in companies and firms to power special

systems.
http://en.wikipedia.org/wiki/Input/outputhttp://en.wikipedia.org/wiki/Computer_multitaskinghttp://en.wikipedia.org/wiki/Input/outputhttp://en.wikipedia.org/wiki/Computer_multitasking

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