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COMPUTER NOTES9TH CLASS

Chapter No. 1

Introduction to Computer

Q1. What is computer? Describe the history of computer.

Mechanical Computing Devices

A Computer is an automatic electronic, calculating device which can process a given input in a prescribed

manner to produce a desired output, at a very high speed with remarkable accuracy. A computer is an electronic

devic

e which we give input and after processing it gives us output. A computer is an electronic device that process

data and converts it into information.

!"!C#$About 3000 years BC, Chinese developed the first calculating machine named Abacus or Soroban. Abacus

consists of a rectangular wooden frame having rods which carry round beads. Counting is done by shifting the

beads from one side to another.

%#&'()*D+$ $,ID* )#,*$

n !"3# A$ %illiam &ughtred, an 'nglish mathematician developed a slide rule. (his device consists of

two movable rules placed side by side on which number were marked.

-!$C!,+$ C!,C#,!(%)

Blas) *ascal +!"#3!""#-, a rench developed the first mechanical calculating machine in !"/#. (his

machine consists of gears, wheels and dials. t was capable of adding and subtracting operations.

"!""!&* DI*)*NC* *N&IN*

Charles Babbage +!1#!2!- an 'nglish mathematician also called ather of modern computer. As

he gave the true concept of computer at Cambridge niversity, he developed Babbage $ifference 'ngine in

!2#3 and Babbage Analytical 'ngine in !233. 4ady Ada Augusta an assistant of Babbage is called the first

programmer.

D%C(%) '*)M!N '%,,*)I('

n !220s 5erman 5ollerith an American developed a machine which used punch card system. (he

machine could sense and punch holes, recogni6e the number and make re7uired calculations. (his machine was

first used in !210s by American Census Bureau.

'%W!)D !I/*N0 M!)/01 C%M-#(*)

n !13, *rofessor 5oward Aiken build the first electromechanical computer 8ark!, by trying to

combine Babbage9s theory and 5ollerith9s punching technologies. 5e completed his pro:ect in !1// with the

help of B8 'ngineers.

*NI!C I)$( *,*C()%NIC C%M-#(*)2'lectronic ;umerical ntegrator And Calculator +';AC- was the first electronic computer made in !1/"

by <ohn *resper 'ckert and <ohn %illiams 8auchly, at the niversity of *ennsylvania, SA. (his was based on

decimal number system and it has no memory.

ASIF ALI RAZA {THE EDUCATORS)




*D$!C I)$( $(%)*D -)%&)!M C%M-#(*)2

'lectronic $elay Storage Automatic Computer +'$SAC- was first computer based on stored program

concept. t was completed by 8ourice %ilkes at Cambridge niversity in !1/1.

*D3!C

'lectronic $iscrete =ariable Automatic Computer +'$=AC- was built by <ohn %illiams 8auchly, <ohn

*resper 'ckert at 8oore School, *ennsylvania in !1>!.

#NI

3!C I)$( C%MM*)CI!, C%M-#(*)2

;=ersal Automatic Computer +;=AC- was the first commercially used computer made by

<ohn *resper 'ckert and <ohn %illiams 8auchly in <une !/, !1>!.Q4. What are generations of computer? *5plain

&enerations of Computer

(he development of electronic computers can be divided into generations depending upon the

technologies used. (he generations of computer are?

irst @eneration +=acuum (ubes- !1/# !1>1

Second @eneration +(ransistors- !1>1 !1">

(hird @eneration +ntegrated CircuitsCs- !1"> !13

ourth @eneration +8icroprocessors- !1# !120ifth @eneration +Artificial ntelligence- !120 onwards

irst &eneration of Computers

=acuum tubes were used in the computers of irst @eneration. (he first generation computers had the

following characteristics or shortcomings?

i. =ery big in si6e

ii. Slow in speed

iii. 4ow reliability

iv. 4arge power consumption

v. $ifficult maintenance

'amples of irst @eneration Computers? ;=AC+niversal Automatic computer-,

*D$!C6 *D3!C

$econd &eneration of Computers

(ransistors were used in the computers of Second @eneration. (ransistors were smaller, reliable as

compared to =acuum (ubes. (hey consumed less power. Second @eneration computers were able to perform a

single operation in microseconds and were capable to store huge data. Second @eneration computers had the

following characteristics?

i. 'tremely reliable as compared to the irst @eneration computers.

ii. Compact in si6e.

iii. 4ess power consumption.

iv. se of card readers, magnetic tapes, magnetic discs, printers etc.





v. se of computer languages.

'ample of Second @eneration Computers? B80/

(hird &eneration of Computers

ntegrated Circuits +Cs- were used in the computers of (hird @eneration. An C chip contains many circuits

such as transistors, diodes and resistors interconnected with one another. 8ini computers were developed in (hird

@eneration.

(hird @eneration computers had the following characteristics0

i. =ery small si6e as compared to the second generation

ii. Consumed very little power

iii. 8ore reliable

iv. 4ess costly as compared to previous generations

v. se of realtime programming

vi. se of multiprogramming

vii. se of $ata Base 8anagement Software

viii.4arge storage capacity

*5amples of (hird &eneration Computers 8B2>, System3"0 series etc.

ourth &eneration of Computers

8icroprocessors +!1!- were firstly used in ourth @eneration computers. (hey contained =4S+=ery

4arge Scale ntegration- circuits. A =4S contained a complete Central *rocessing nit+C*- on a single

semiconductor chip. ourth @eneration computers had the following characteristics0

i. =ery efficient and fast

ii. =ery 4arge storage

iii. =ery little power consumption

iv. se of 8icroprocessor

v. se of (.=. screens now called monitors

vi. Could perform arithmetical and logical operations

*5amples of ourth &eneration Computers 789:6 78916 !pple series etc.

ourth &eneration of Computers

Artificial ntelligence +A- and 'pert Systems are the technologies of ifth @eneration of computers. (here

was very little hardware change in ifth @eneration computers but a revolution in software. ollowing are the

characteristics of ifth @eneration computers?

i. Artificial ntelligence

ii. 'pert Systems

iii. 4arge thinking power as compared to previous generations.

iv. ncreased speed

v. ncreased efficiency

vi. educed si6e

vii. educed cost





Q;. What are different types of computers according to their <or=ing? *5plain. !ns. (ypes of

Computers according to their <or=ing2

(here are three types of computers according to their working and design?

!. Analog Computers

#. $igital Computers

3. 5ybrid Computers

!nalog Computers

An analog computer accepts data in continuous or physical form and represents it in a suitable form to

perform scientific operations. t processes analog data e.g. speed, pressure, temperature, fluid flow, voltage, current

etc. Analog Computers are Special *urpose Computers. (hey are very fast. 'amples of !nalog Computers

Speedometer, thermometer etc.

Digital Computers

An analog computer accepts data in form of digits and represents it in the form of discrete numbers. t

processes digital data and performs arithmetic and logic operations. $igital Computers are @eneral *urpose

Computers. (hey are accurate as compared to Analog Computers. Computers at our schools, homes and offices are

digital computers.

*5amples of Digital Computers? *Cs or computers at our homes.

'ybrid Computers

5ybrid Computers are combination of features of digital and analog computers. (hey are Special *urpose

Computers which are fast and accurate.

*5amples of Digital Computers? Computers at 5ospitals in Cs, telemetry, spaceships, guided missiles

etc.

Q>. What are different types of computers according to their sies? *5plain.

!ns. (ypes of Computers according to their sies2

(here are four types of computers according to their si6es?

!. Super Computer

#. 8ainframe Computer

3. 8ini Computer

/. 8icrocomputer$uper Computers

Super Computers are the largest and the fastest computers which can perform hundreds of millions of

instructions per second. irst Super Computer was developed in !120s.

*5amples of $uper Computers? CAD!, CAD#, CDB' #0> etc.





ields in <hich $uper Computers are used Space 'ploration, %eather forecasting, Aircraft $esign, ;uclear

esearch etc.

Characteristics of $uper Computer

i. 'traordinary computing power.

ii. Special *urpose Computers.

iii. =ery 'pensive

iv. sed by very large organi6ations.

Mainframe Computers

8ainframes are largescale computers. (hese computers need very large rooms and other arrangements like

cooling etc. 8ainframes are very fast and have very large memory. (hey support many users and can do different

:obs for different users. n short?

@! large digital computer serving 1::0;:: users and occupying a special air0conditioned room is called a

mainframe computer.A

*5amples of Mainframe Computers? B8/3/!, CDB' !" etc.

ields in <hich Mainframe Computers are used? Banks, Airlines, niversities etc.

Characteristics of Mainframe Computer

4arge Scale Computers

=ery fast

=ery 4arge 8emory

Support !00/00 users simultaneously

Mini Computers

8ini Computers can support multipleusers and multiple tasks like mainframes

through the use of terminals. (hey were firstly used in !1"0s. n short?

EA midsi6ed computer, usually fitting within a single cabinet about the si6e of a refrigerator, that has less memory

than a mainframe is called a 8ini Computer.F

%r

EComputer that possesses the same components as large mainframes but has reduced memory and slower

processing speeds is called a 8ini Computer.F

*5ample of Mini Computers -D-01

ields in <hich Mini Computers are used 4arge Businesses, 'ducation and @overnment sector etc.

Characteristics of Mini Computer

i. 8ini Computers can handle larger amount of data than microcomputers

ii. (hey perform the functions of a mainframe computer with slightly slower speed.

iii. (hey support multiple users

iv. (hese computers are 8ultiple *rocessing Computers.

Micro Computers

A 8icro Computer is a relatively inepensive computer that is rapidly being used in all application areas. n





short?

@! small digital computer based on a microprocessor 3,$I Circuit2 and designed to be used by one

person at a time is called a microcomputer.A

*5ample of Micro Computers I"M -C6 !(B( etc.

ields in <hich Micro Computers are used

4arge Businesses, 'ducation and @overnment sector etc.

Characteristics of Micro Computers

i. 8icrocomputers are inepensive computers.

ii. 8icrocomputers are smaller in si6e.

iii. 8icrocomputers are very powerful but less powerful than super, mini or mainframe

computers.

iv. 8icrocomputers are @eneral *urpose Computers.

Q;. What is the impact of computers on society? !lso e5plain the use of computers in different fields of life.

Impact of Computers on $ociety

Computer is known as the most popular and wonderful discovery of the #!st

century. t is seen at houses,

offices, school, colleges, universities, banks and hospitals. Computers are being used as typewriters, calculators,

=Cs, (=s, telephones and communicational tools.

!pplications of Computers

Computer has applications in the following fields of life.

!pplications in "usiness

Computers are being used by all businesses. Some of computer uses in business are as under?

(o record stocks

(o make customer bills

(o analy6e sales

(o calculate employee’s pay

!pplications in "an=ing

Banks are the largest users of computer. Some of computer uses in banking are as under?

(o record day to day processing of customer ‟s account

(o facilitate customers in using their credit cards for purchasing a product

(o make automatic debit form

(o update customer ’s accounts

!pplications in *ducation

(here are a number of ways in which a computer can educate its users. (hey are as under?

o Computer !ssisted InstructionsC!I2

sing computer as an aid to teach a sub:ect is called CA +Computer Assisted nstructions-. n this method,





following techni7ues are used?

$ialog

(utorial

(esting

'valuating the tests

$rill and *ractice

!pplications in Medical ield

Computers are used in medical field to?

Geep track of patients appointments

$iagnosis and treatment

Assign medicine to certain patient depending on the patient data

Geep track of the history of patients

!pplications in $cience

Computers are vastly used in sciences such as physics, biology, chemistry, mathematics, agricultural

sciences, computer science and nuclear physics etc. t helps in scientific researches.

!pplications in -roduct Design and Manufacturing

8anufacturing companies use computers from the design stage to the manufacturing stage. Computer Aided

$esign +CA$- software help to develop a representation of the product and help testing it in a variety of simulated

environments.

Q. What is a programming language? What is the difference bet<een a 'igh ,evel ,anguage and a ,o<

,evel ,anguage?

-rogramming ,anguages

*rogramming is a way to communicate with computer. Computer understands binary number system only

consisting of digits 0 and !. A group of binary digits is called a code. %hen a user wants to communicate to the

computer, he needs to give the computer a set of instructions. (his is done with the help of a programming

language. (here are two ma:or categories of languages?

'igh ,evel ,anguages

5igh level languages are closer to human languages than lowlevel language and include statement like

@&(& and *;( which are regular words. nlike the assembly language, the program of high level languages do

not have to be written for a particular computer, but it can be eecute on any machine that has a compiler for that

language.

,o< ,evel ,anguage

(here are two 4ow 4evel 4anguagesH 8achine 4anguage and Assembly 4anguage?





Machine ,anguage

A set of binary instruction codes which a computer directly understands is called 8achine 4anguage. t is a

4ow 4evel 4anguage. t differs from computer to computer. t is also called Ilanguage of the processor ‟ or Imother

language of computer ‟. t is hard to understand by user as it is in the form of binary digits.

!ssembly ,anguage

Assembly 4anguage is also a low level language but it uses short symbolic phrases understandable by user J

programmer. (hese alphanumeric symbols are called mnemonic codes. Assembly 4anguage is not directly

under

standable by the computer. So, each program of Assembly 4anguage is assembled into 8achine 4anguage

with the help of an assembler. An assembler is a program which converts Assembly 4anguage program into

8achine 4anguage.

Q. "riefly describe the follo<ing languages.

i2 "!$IC ii2.%)(!N iii2 C%"%, iv-!$C!, v2!D! vi2 CEE vii2 C

"!$IC

BASC +Beginner ’s Allpurpose Symbolic nstruction Code- was developed in !1"/. t is close to 'nglish.

A person with little programming knowledge can t is?

'asy to nderstand

'asy to %rite programs

'asy to locate and debug errors

%)(!N %)mula ()!Nslation2

&(A; was developed in !1"/ for B8 computers. ts latest version is &(A; 10. t

was used to solve?

8athematical problems

Scientific problems

'ngineering problems

C%"%, C%mmon "usiness %riented ,anguage

2

C&B&4 was developed in !1>1. t was developed for general, commercial and business purpose. t wasused handle large amount of data related to?

*ayroll Credit and debit accounts Business applications

-!$C!,

*ascal was developed during the early !10‟s. *ascal is also a 544 named after the rench mathematician

and scientist Blaise *ascal. t is a general purpose language.

C ,anguage

C language was developed in !1/ by Brian Garnighan and $ennis itchie. t is used for developing

&perating Systems. C is etremely powerful 5igh 4evel 4anguage.

CEE

CKK was developed in the early !120s by B:arne Stroustrup. t is the most powerful 5igh 4evel 4anguage.

t is like C but supports &b:ect &riented *rogramming.

Q. Describe the language translators.

ASIF ALI RAZA {THE EDUCATORS)Page




(here are three types of translators or language processors?

Compiler

A compiler is translating software which converts the 5igh 4evel 4anguage programs into machine

language. t converts the whole program at once.

Interpreter

An interpreter is translating software which converts the 5igh 4evel 4anguage programs into machine

language linebyline.

!ss

embler

An assembler is also system software which assembles J converts assembly language programs into

machine language.

Chapter No. 4

Computer Components

Q. No. 1 What is difference bet<een computer hard<are and soft<are?

'ard<are

All the physical components of a computer are collectively called hardware. t includes all the input devices,

output devices and system unit e.g. keyboard, mouse, scanner, mic, monitor, printer, C* etc

$oft<are

All the programs of a computer are collectively called software. A software is a set of instructions which

tells the computer what to do e.g. %indows, 8S&ffice, @ames, 8edia *layer etc.

Q. No. 4 Define input and output dev ices.

Input devices

nput devices are used to enter data or instructions into a computer. e.g. keyboard, mouse, mic, scanner,

light pen etc.

%utput devices

&utput devices give out the results to the user. (hey show results and outputs. e.g. monitor, printer, speaker

etc.

Q. No.>. What is the Fsystem unit+?

$ystem #nit

t is the main unit of a computer system. t contains motherboard, microprocessor, storage devices, J& cards,

hard disk, memory, disk drives etc.

Q. No. ; What is C-#? What are its different parts? *5plain briefly.

C-# Central -rocessing #nit2

C* is the brain of a computer. t controls the entire operation of a computer system. t controls the entiresystem and eecutes instructions.

-arts of C-#

A C* chip consists of mainly three units

!. Control nit +C-





#. Arithmetic L 4ogic nit +A4-

3. 8emory nit +8-

Control #nitC#2

Control nit is the most important part of the C*. t controls the overall datatraffic that takes place within

a computer. t issues necessary commands to relevant units. t fetches instructions from A8 and stores them in the

instruction register and then transfers them to A4 registers. t acts like a traffic policeman.

!rithmetic B ,ogic #nit !,#2?

A4 consists of a number of adder and logic gates. t performs all the arithmetic and logic operations that

take place in a computer. Arithmetic operations are addition, subtraction, multiplication etc. 4ogic operations are

comparison operations, A;$, &, ;&( etc.

C-# Memory

A4 and C need memory. (his memory consists of small temporary memory locations. (hese temporary

memory locations are called registers.

Q. What is meant by FMain Memory+?

Main Memory and its Importance 8ain memory is the fastest computer ’s internal memory. t is also called primary memory.

t is generally on semiconductor chips. (hese chips are connected to the C* and the motherboard.

8ain memory is very fast and is directly accessible by the C*. %ithout main memory computer

would not have been so fast as it is now.

(ypes of Main Memory

(hese are generally two types of main memory?

)eal %nly Memory )%M2

&8 is the permanent memory of a computer. &8 provides the C* the instructions during the startup

process or booting process. &8 also contains the drivers for basic inputJ output devices like keyboard and

monitor.

)andom !ccess Memory )!M2

A8 is a very important memory of a computer. t is also called read and write memory. A8 is a volatile

memory because the data in A8 is lost as soon as an electricity failure occurs. *rograms are brought in A8 for

eecution.

Q. . What is meant by Fsecondary memory+ or Fbac=ing storage+?

$econdary Memory

Secondary memory is also called the backing storage of a computer. (he data in secondary storage is not

lost even if an electricity failure occurs. t is a nonvolatile memory. t is not directly accessible by the C*. t is a

slow but large memory. e.g. 5ard $isk, loppy $isk, C$ etc.

QG. What is meant by Fbuses+ in computer? What are types of buses?

ASIF ALI RAZA {THE EDUCATORS)Page 1!




"uses

A bus is an electrical path among different hardware parts of a computer. A bus connects A4, C,

8emory and other parts of a computer.

(ypes of "uses (hese are three types of buses?

1. (he Data "us

4. (he !ddress "us

>. (he Control "us

(he Data "us

$ata bus is an electrical path which connects the C*, memory and other parts on the motherboard. t

carries data. ts si6e differs from computer to computer. An 2 bit data bus can transfer ! byte at a time while a !" bit

data bus can transfer # bytes at a time.

(he !ddress "us

(he address bus carries memory addresses. t connects the C* with the memory. 4arge si6e address bus

can address large memory. An 2 bit data bus can address #2 memory locations.

(he Control "us

(he control unit controls the overall computer system. t sends control commands through the control bus.

t provides two way transfer between the secondary storage and main memory.

Q9. What are ports? *5plain.

-orts A port is an interface. t provides a direct link with the computer. All the J& devices are connected to the

computer through ports.

(ypes of -orts

1. $erial -orts

4. -arallel -orts

$erial -orts A serial port provides a link through which only one bit can be transferred at a time.

t can have 1 or #> pins.

*5amples C&8!, C&8#, C&83 etc.

-arallel -orts

A parallel port provides a link for transmitting fast flow of data. t can transfer more that one bits at

a time. t can transfer 2 or !" bits are a time.

*5amples 4*(!, 4*(#, 4*(3 etc.

Q .H. Describe the main functions of C-#.

unctions of C-#C* is the brain of computer. t performs all the arithmetical and logical operations of a computer.

t performs the following functions?

!. t performs all the arithmetic operations such as addition, multiplication, subtraction, division

etc.





#. t performs all the logical operations of a computer such as comparing two values. 4ogic operations

are comparison operations, A;$, &, ;&( etc.

3. t controls the flow of data among different parts of the computer. t is done by Control nit of C*

/. C* eecutes all programs.

Q. 1:. Describe the <or=ing and function of !,#.

Wor=ing and unction of !,#

Arithmetic and 4ogic nit +A4- contains a number of adder and logic circuits and registers. A4

perfo

rms all the processing i.e. arithmetic and logic operations of a computer.

*8!M-,*?

Consider the addition of two numbers A and B stored in the main memory. Control nit interprets the

instruction and transfers the number A from the main memory to the accumulator. (hen it transfers the number B to

some other available register. (hen these numbers are added by adder circuits and the result is stored in the

accumulator register. esults can be sent to the main memory.

Chapter No. >

Input %utput Devices

Q1. Define input dev ices.

Input devices

nput devices are used to enter data or instructions into a computer. 'amples? Geyboard, mouse,

microphone, scanner, light pen etc.

Q4. Define output devices.

%utput devices

&utput devices present J give out the results to the user. (hey show results and outputs. 'ample? 8onitor,

printer, plotter, speaker etc.

Q>. Write a note on the =eyboard.

/eyboard

A board with a set of input keys on a terminal or computer is called a keyboard. t includes the standard

typewriter keys, several speciali6ed keys. Geyboard is the fundamental input device of a computer. t is used to

enter data and instructions into a computer. @enerally, a keyboard has a M%'(D arrangement. t is connected

through a dedicated keyboard port with the system unit.

$tyles of /eyboard

a- *C J N( style

b- A( Style

Division of a /eyboard

A keyboard is divided into four general areas?

!lphanumeric =eyboard

t includes?

Alphabetic keys? (hese keys range from a 6 or A O.

;umber keys? (hese keys range from 0 to 1.





*unctuation keys and special keys? (hese keys include K, P, Q, L etc.

Numeric /eypad

t is a set of number keys at the right of a keyboard. Geys in numeric keypad are arranged like a

calculator ‟s keys.

unction /eys

unction keys are from ! to !#. (hey are located on the top of a keyboard. 'ach of these keys has a

special function which depends on the software.

$creen Navigation and *diting /eys

(hey are used to move up, down, left, right, beginning or end of a document. (hey include?

i- 'SC ii- C(4 iii- A4( iv- ight Arrow v- 4eft Arrow

vi- p Arrow vii- $own Arrow

Q;. Write a note on the mouse. !ns. Mouse

A mouse is another useful input device. t is used to enter instruction into a computer. t is the

most common input device with %indows operating systems. A mouse is a handheld device with a ball

on its bottom. t is rolled on a mousepad. A mousepointer also moves with the mouse. t also has two or

three buttons which are used to select various options.

Q. Write a note on the Joystic=.

Koystic=

A :oystick is a handheld input device with a moving stick and buttons. t is generally used for

playing computer games.

A :oystick is computer input device, especially helpful when playing computer games. t consists of

a handle that can be pointed in different directions. Because the computer can sense which direction the

:oystick is pointed, it can be used to control the movements of ob:ects displayed on the computer screen.

Q. Write a note on the scanner.

$canner

Scanner in an input device which converts typed documents, pictures or photographs into electronic files.

Scanner is a device that reads a printed page and converts it into a graphics image for the computer. A scanner

normally has an &C which recogni6es the tet and converts into %&$ files.

(ypes of $canners

latbed Scanners, 5andheld Scanners, $rum Scanners, &verhead Scanners or ilm Scanners

QG. Write a note on the trac=ball.

(rac=ball

A trackball is also an input device. t is normally used in laptop computers instead of mouse. t is

like a mouse turned upsidedown. t has a ball on its top which is moved with the finger tips. A cursor or

pointer also moves with the movement of the ball. t is best suited for the handicapped people who cannot

move the arm but can move their fingers.Q9. Write a note on the *lectric ,ight -en.

*lectric ,ight -en

A light pen is an input device. t is normally attached to some =ideo $isplay nit. t has a tube which

senses input. (he data is directly written on the screen. 'lectric 4ight *en is a lightsensitive input device shaped





like a pen, used to draw on the computer screen or to make menu selections. As the tip of the light pen makes

contact with the screen, it sends a signal back to the computer containing the y coordinates of the piels at that

point.

QH. What is meant by voice recognition? *5plain.

Microphone and 3oice$peech )ecognition

A microphone is another input device which transfers sounds and voice into digital files of computer.

Sounds can be entered into a computer with the help of a microphone.

3oic

e )ecognition

(ranslating voice into tet is an ability known as voice recognition. ;ormally, sounds are spoken in a

microphone and the computer recogni6es these sounds and converts into tet. ollowing steps are involved in

speech recognition?

!. ser speaks the sound into a microphone.

#. Computer digiti6es the sound.

3. Computer matches the digiti6ed sound with eisting templates

/. Computer converts the sound into tet or it performs some operation.

Q1:. Write a note on the *lectric ,ight -en.

Digital Camera

A digital camera converts video images in digital form and saves them in computer ’s memory. (hese

images can be edited on computer.

Q11. Write a note on Dis= Drives.

Dis= Drive

t is a device that reads data stored on a magnetic or optical disk and writes data onto the disk for storage.

(he most popular storage media are the diskettes +or floppy disks- and the 5ard $isks +or fied disks-. (he data

stored on these disks is called softcopy. A readJwrite head which floats above the spinning disk writes and reads

data to and from the disk.

Q14. Write a note on Monitors. What are different types of monitors? !ns. Monitors8onitor is a display screen used to present output from a computer to the user. *ictures that are displayed

on monitor screen are combination of very small dots called piels. (he number and si6e of piels determines the

7uality of the image formed on screen. @reater is the number of piel, higher will be the resolution and better will

be the image 7uality.

(ypes of Monitors

i. C&! Colour &raphic !dapter2 Monitors can display four colours with a resolution of 3#0 #00

piels.

ii. *&! *5tended &raphic !dapter2 Monitors can display siteen different colours with a

resolution of "/0 /20 piels.

iii. 3&! 3ideo &raphic !dapter2 Monitors can display #>" different colour shades with a

resolution up to #0 /00 piels.

iv. $3&! $uper 3ideo &raphic !dapter2 Monitors can display images at a resolution from 200





"00 piels to !#20 !0#/ piels.

v. ,CD ,iLuid Crystal Display2 Monitors are flat, light weight, portable monitors and use little

power. (hey are normally found with laptops.

Q1>. Write a note on -rinters. What are different types of printers?

-rinter

*rinter is a device that converts computer output into printed images. (hey produce the hardcopy of the

stored data.

(ypes of -rinters

1. Impact -rinter

4. Non0impact -rinter

Impact -rinter

mpact *rinter prints on the paper by striking the paper. (here are three types of impact printers?

Dot0matri5 -rinter

$ot matri printer is an impact printer. t is a printer in which each character is formed from a matri of

dots. t comes with 1, !2, #/ or 3# pins with inked soaked ribbon.

-rinting Mechanism

*ins of a dot matri printer strike the ink soaked ribbon which strikes the page. (his process repeats

and characters are printed.

$peed of Dot matri5 -rinter

Speed of dot matri printers ranges from >0 to "00 characters per second.

Daisy0<heel -rinter

$aisywheel printer is also an impact printer. t comes with fied characters at the end of the spokes. (hese

spokes are fied on a wheel which rotates to bring the re7uired character against the paper. t is also called

character printer. t is slow than a dotmatri printer but it produces high 7uality output.,ine -rinter

(he line printer is a form of high speed impact printer in which one line of type is printed at a time. *rint

speeds of "00 to !#00 linesperminute +approimately !0 to #0 pages per minute-. Some of these printers can print

over 3000 lines per minute.

Non0impact -rinter

;onimpact *rinter prints on the paper without striking the paper. (here are four types of non

impact printers?

*lectrostatic -rinter

'lectrostatic *rinters are very high speed nonimpact printers. A charges image is formed on the paper by

electric field. (his paper is passed through an inkfog. (he ink particles adhere at the image on the paper to form a

visible image. (he paper is then passed through the heated roller for fiing the image.

*lectro0thermal -rinter


http://www.answers.com/topic/computer-printer

http://www.answers.com/topic/computer-printer




(hermal *rinters produce the output on heat sensitive way paper. (hese were popular a few years ago

because they are portable and cheap. But the drawback is that they re7uire special heat sensitive way paper.

In=Jet -rinter

nk:et printer is a printer that prints characters and images by shooting small droplets of ink at the paper.

Advantages of the ink:et printer include speed, high resolution, and 7uiet operation.

(hese printers re7uire ink reservoirs.

,aser -rinter

4aser *rinters are the fastest nonimpact printers. (hey use electro photographic technology. t

is a printer that uses a laser and the electro photographic method to print a full page at a time. (he

laser RpaintsR a charged drum with light, to which toner is applied and then transferred onto paper.

$peed of ,aser -rinter

A laser printer can print at a speed of #0000 lines per minute.

Q1;. Write a note on plotters. What are different types of plotters?

-lotter

*lotter is a printing device that draws images on paper using ink pens or pencils.

A plotter draws images as a series of pointtopoint lines.

(ypes of -lotter

Drum plotter

A drum plotter can print on very large pieces of paper. (hey produce continuous output.

!. latbed *lotter

A flatbed plotter will draw diagrams with pens on a piece of paper that is fied on a flat tablet.

Q1. Write a note on CD0W)I(*)$. What are different types of CD0W)I(*)$?

CD0W)I(*)

A C$ drive that supports write once +C$- or rewritable media +C$%- is referred as C$%('. AC$%(' has a writehead which can write on C$ or C$%. C$s are available at very low cost and large

memory. ;ormally a C$ can store upto 00 8B of data.

Q1. What is meant by the term hard copy and soft copy?

'ard Copy

(he printed output of a printer is called hard copy.

$oft Copy

(he machine‟s output displayed on screen is called soft copy.





Chapter No. ;

$torage Devices

Q. 1 What is meant by computer memory? What are different types of computer memory?

Computer Memory

(he area of a computer where programs and data are stored is called memory. t stores the programs and

data permanently or temporarily. (he processor or C* has almost direct access to the main memory so in order

to match the C* speed the main memory is made very high speed memory. t is epensive also.

(ypes of Computer Memory

(here are two ma:or types of computer ’s memory?

1. Main Memory or Internal Memory or -rimary Memory

(he main memory +or primary storage- of a computer is memory that is wired directly to the

processor, consisting of )!M and possibly )%M . (he processor or C* has almost direct access to the

main memory. n order to match the C* speed the main memory is made very high speed memory. t is

epensive also.

4. $econdary Memory or "ac=ing $torage or !u5iliary $torage

Secondary memory +or secondary storage- is the slowest and cheapest form of memory . t provides

very high storage capacity. t cannot be accessed directly by the C*. Secondary memory devices include

magnetic disks like hard drives and floppy disks H optical disks such as C$s and C$&8s H and

magnetic tapes, which were the first forms of secondary memory.

Q. 4 What are )elation of Different Memory #nits?


http://www.memorymanagement.org/glossary/m.html#memory-1

http://www.memorymanagement.org/glossary/r.html#ram


http://www.memorymanagement.org/glossary/r.html#rom


http://www.webopedia.com/TERM/s/memory.htm

http://www.webopedia.com/TERM/s/CPU.htm


http://isp.webopedia.com/TERM/S/hard_disk_drive.htm

http://isp.webopedia.com/TERM/S/floppy_disk.htm


http://isp.webopedia.com/TERM/S/optical_disk.htm

http://isp.webopedia.com/TERM/S/compact_disc.htm


http://isp.webopedia.com/TERM/S/CD_ROM.htm


http://isp.webopedia.com/TERM/S/tape.htm


http://www.memorymanagement.org/glossary/m.html#memory-1



http://www.webopedia.com/TERM/s/memory.htm


http://isp.webopedia.com/TERM/S/hard_disk_drive.htm


http://isp.webopedia.com/TERM/S/optical_disk.htm







Memory #nits

;ibble #3 S / bits

Byte #!0 2 bits

Gilo Byte ##0 !0#/ Bytes

8ega Byte #30 !0#/ Gilo Bytes

@iga Byte #/0 S !0#/ 8ega Bytes

(era Byte #>0 S !0#/ @iga Bytes

W%)D? t depends from processor to processor. t is normally of 2 bytes.

Q. >. What is meant by )!M? Why )!M is faster than secondary storage devices?

)!M

A8 is the working memory of a computer where data and programs are temporarily stored. A8 only

holds information when the computer is on. 'verything stored in A8 is lost when the computer is turned &.

(hat’s why it is called volatile memory. t is also called ) ead!ndwrite Memory. f A8 si6e of a particular

computer is smaller, then a program larger than A8 si6e is loaded in parts, which slows down the computer.

4arger A8 si6es provide greater speed because whole program is loaded at once.

Q;. What is meant by )%M? What are its types?

)%M

&8 is a type of main memory whose contents can be accessed and read but cannot be changed. t is a

semiconductor memory programmed by the manufacturer. (he data in &8 is not lost when the computer is turned

&, that’s why it is called a nonvolatile memory.

-)%M -rogrammable )ead %nly Memory2 t is a type of &8 which can be programmed

only once

Q. What is meant by $IMMs and DIMMs? $IMM

Single nline 8emory 8odule +S88- is a circuit board memory which holds a group of memory chips.

S88s have capacity from ! 8B to 3# 8B or greater.

DIMM

+$ual nline 8emory 8odule- is a small circuit board holding a bank of memory chips, with

different contacts on each side, allowing for twice the number of pins as a S88. A8‟s capacity can be increased

by plugging in more $88s.

Q.. 'o< is data <ritten to a read from a floppy?

(he floppy has a window with a springloaded metal shutter. (he shutter is pushed back which uncovers the

window when it is inserted into the disk drive. (he drive rotates the disk inside its protective covering at a speed of

300 rpm. eadJwrite head contacts its eposed surface through the window. ecording is done magnetically in

concentric circles called tracks. Computers disks use sector organi6ation to store data and retrieve data. A sector

ASIF ALI RAZA {THE EDUCATORS)Page 1




and a track number is need to read from a particular location of the disk. An access arm containing the read head is

moved under program control to read from a particular location. $ata are read when the re7uired sector passes

under the head. t is found in 3.>F or >.#>F of diameter.

Q. G. What is 'ard Dis= or i5ed Dis=?

'ard Dis= or i5ed Dis=

(his is your computers main storage device, this is where programs are located. 4arge capacity, mechanical,

magnetic, computer storage device that stores your programs and data. A hard disk is a sealed unit containing a

number of platters in a stack. 'ach platter has two recording surfaces. (he disks or platter in a hard disk spin

continuously at a speed of 3"00 rpm to !0000 rpm within a sealed enclosure.

Q. 9. What is CD )%M?

Compact Dis= )ead %nly Memory CD0)%M2

t is a secondary storage media which can store about 008B of data. t stores data in machine





readable form. t is a faster storage media than magnetic tapes because it stores C$&8 discs are read using C$

&8 drives, which are now almost universal on personal computers.

'o< are data stored on CD0)%M

$ata are recorded on C$&8s‟ reflective surfaces in form of pits and lands. (he pits are tiny reflective

pumps that are burned in by a laser beam. A spot that reflects a laser beam is interpreted as I!‟ and a spot that

scatters and does not reflect the laser beam into the sensor is interpreted as I0‟.

'o< are data read from CD0)%M

A C$&8 re7uires a C$$rive or C$*layer which read data from C$&8s.

ASIF ALI RAZA {THE EDUCATORS)Page 2!

sir asif ali raza computer notes class 9thdocx

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