01class1-2 introduction.ppt

8/17/2019 01class1-2 introduction.ppt

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3hat Is A Computer4

A computer is an electronic de"ice5operating under the control ofinstructions 6software7 stored in its ownmemor# unit5 that can accept data

6input75 manipulate data 6process75 andproduce information 6output7 from theprocessing.

8enerall#5 the term is used to descri$e

a collection of de"ices that functiontogether as a s#stem.


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3hat Does A Computer Do4

Computers can perform four general

operations5 which comprise the information

processing c#cle.• Input

• rocess

• utput

• Storage


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Dept. of CSE :

3h# Is A Computer So owerful4

• 2he a$ilit# to perform the information

processing c#cle with ama0ing speed.

• ;elia$ilit# 6low failure rate7.• Accurac#.

• A$ilit# to store huge amount of data and

information.• A$ilit# to communicate with other computers.


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Dept. of CSE <

=ow Does a Computer >now

what to do4

• It must $e gi"en a detailed list of instructions5

called a compute program or software5 that

tells it e!actl# what to do.• ?efore processing a specific %o$5 the computer

program corresponding to that %o$ must $e

stored in memor#.

• nce the program is stored in memor# the

computer can start the operation $# e!ecuting

the program instructions one after the other.


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Dept. of CSE 11

Input De"ices

• 2he input de"ice is usuall# a -e#$oard where programs

and data are entered into the computer.• E!amples of other input de"ices include

B )ouse

B o#stic- B @ight pen B 2rac-$all B ptical Scanner B 2ouch screen B oice input


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2he )ouse

Is a pointing de"ice which is used to control

the mo"ement of a mouse pointer on thescreen to ma-e selections from the screen. A

mouse has one to fi"e $uttons. 2he $ottom of

the mouse is flat and contains a mechanism

that detects mo"ement of the mouse.


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Dept. of CSE 1,

S#stem nit

• Data and instructions recei"ed from the input de"ice arestored and processed in the S#stem unit. 2he Central

rocessing nit and )emor# nit are together called as

System Unit.


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2he Central processing nit

• 2he data and instructions recei"ed from theinput de"ice are processed in this unit.

• It is considered the $rain of the computer.

• It consists of two functional units.

B Control nit 6C7 B Arithmetic and @ogic nit 6A@7


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Dept. of CSE 1G1G

Arithmetic@ogic nit performs arithmetic and

logical operations

Control nit controls the order in which theprogram instructions are e!ecuted.

Its functions are

B Fetches data and instructions from main memor#

B Interprets these instructions

B Controls the transfer of data and instructions to

and from main memor#

B Controls input and output de"ices.

B "erall super"ision of computer s#stem


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Dept. of CSE 19

Primar +torag

• rimar# storage is a place where the programs and data

are stored temporaril# during processing.

• 2he data in primar# storage are erased when thecomputer is turned off.


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utput De"ices

utput de"ices ma-e the information resulting from theprocessing a"aila$le for use. 2he two output de"ices morecommonl# used are the printer and the computer screen.2he printer produces a hard cop# of #our output5 and thecomputer screen produces a soft cop# of #our output.

Some of the other output de"ices are

•lotter •plasma displa# panels•@CD displa#s•"oice output


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Dept. of CSE 1<

Secondar# storage au!iliar# storage

• Au!iliar# or secondar# storage is used for $othinput and output.

• It is the place where the programs and data are

stored permanentl#.• 3hen the computer is turned off the programs

and data remain in the secondar# storage read#for the ne!t time when it is needed.

• 2he most common t#pes of au!iliar# storageused on personal computers are flopp# dis-s5hard dis-s and CDH;) dri"es and flash dri"es.


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Flopp# Dis-s

A flopp# dis- is a porta$le5 ine!pensi"e

storage medium that consists of a thin5

circular5 fle!i$le plastic dis- with a magneticcoating enclosed in a s/uareHshaped plastic

shell.


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Dept. of CSE '1

=ard Dis-s

• Another form of au!iliar# storage is a hard dis-. A hard dis- consists of one or more rigid metalplates coated with a metal o!ide material thatallows data to $e magneticall# recorded on thesurface of the platters.

• 2he hard dis- platters spin at a high rate ofspeed5 t#picall# ,** to 9'** re"olutions per

minute 6;)7.• Storage capacities of hard dis-s for personalcomputers range from 1* 8? to 1'* 8? 6one$illion $#tes are called a giga$#te7.


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Dept. of CSE ''

Compact Discs

• A compact dis- 6CD75 also called an optical disc5 is a

flat round5 porta$le storage medium that is usuall#

,.9 inch in diameter.

• A CDH;) 6read onl# memor#75 is a compact disc

that used the same laser technolog# as audio CDs

for recording music. In addition it can contain other

t#pes of data such as te!t5 graphics5 and "ideo.

• 2he capacit# of a CDH;) is 9* )? of data.


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Dept. of CSE ',

• =ardware 2he ph#sical elements of acomputing s#stem 6printer5 circuit $oards5 wires5

-e#$oardJ7

• Software 2he programs that pro"ide the

instructions for a computer to e!ecute


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Dept. of CSE '

Computer Software

Software

S#stem Software Application Software


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S#stem Software

• S#stem software consists of programs thatmanages the computer resources.

•Di"ided into three classes

Bperating S#stemHuser interface5 data$aseaccess

BS#stem support softwareHother operational

ser"ices li-e dis- format programs

BS#stem De"elopment software H languagetranslators and de$ugging tools


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Dept. of CSE '9

perating S#stem $asics

• perating S#stem is an integrated collection ofprograms which ma-e the computer operational

and help in e!ecuting user programs.

• It acts as interface $etween the man and machine

• It manages the s#stem resources li-e memor#5

processors5 inputHoutput de"ices and files.

• Single user operating s#stem5 multi user operating

s#stem5 real time operating s#stem etc.• E!amples are DS 5 KIL 5 3indows


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Dept. of CSE '<

3ord rocessing

• 3ord rocessing software is used to create and printdocuments. A -e# ad"antage of word processing

software is that users easil# can ma-e changes in

documents.


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Dept. of CSE (*

Electronic Spreadsheets

• Electronic spreadsheet software allows the user to

add5 su$tract5 and perform userHdefined calculationson rows and columns of num$ers. 2hese num$ers

can $e changed and the spreadsheet /uic-l#

recalculates the new results.


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Dept. of CSE (1

Data$ase Software

• Allows the user to enter5 retrie"e5 and update data inan organi0ed and efficient manner5 with fle!i$le

in/uir# and reporting capa$ilities.


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Dept. of CSE ('

resentation 8raphics

• resentation graphic software allows the user to

create documents called slides to $e used in ma-ingthe presentations. sing special pro%ection de"ices5

the slides displa# as the# appear on the computer

screen.


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Dept. of CSE ((

Computer @anguages• )achine @anguage H nl# programming language

a"aila$le in earlier da#s

B Consists of onl# *Ms and 1Ms

• S#m$olic language or Assem$l# languageH

B s#m$ols or mnemonics used to represent instructions

B hardware specific

• =ighHle"el languagesH English li-e language using whichthe programmer can write programs to sol"e a pro$lem.

B more concerned with the pro$lem specification andnot oriented towards the details of computer.

B eg C5 C++5 CN5 Fortran5 ?ASIC5 ascal etc.

Differences $etween =igh le"el @anguage


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Dept. of CSE (,

Differences $etween =igh le"el @anguage

and )achine @anguage

"acine language

• ses two s#m$ols * and1

• Each instruction is ase/uence of *Ms and 1Ms

• Can $e directl# e!ecuted• Difficult to understand5

write5 modif# and de$ug

• Efficient6fast7

• Kot standardi0ed• Called first generationprogramming language

#ig level language

• ses alpha$ets5 digits5punctuations5 specials#m$ol

• Each instruction is a English

li-e statement• Cannot $e directl# e!ecuted

• Eas# to understand5 write5modif# and de$ug

• @ess efficient6slow7

• Standardi0ed

• Called third generationprogramming @anguage


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Dept. of CSE (

@anguage translators

• Assem$lerH ta-es assem$l# language programas input and translates it into machinelanguage

• CompilerH ta-es entire high le"el languageprogram as input and translates it into machinelanguage

• InterpreterHta-es one statement of high le"el

language program as input and translates itinto machine language and e!ecutes it


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Dept. of CSE (G

Differences $etween Compiler and

Interpreter

• All errors that occur in

the program are listed

and displa#ed

• De$ugging is faster • ;e/uires more

memor#

• Costlier

• Errors that occur onl#

in the statement $eing

ta-en for translation

are displa#ed• De$ugging is slower

• ;e/uires less

memor#

• Cheaper


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Dept. of CSE (9

Computer )emories

2he computer memor# is classified into

• )ain memor#Hrimar# storage

• Secondar# memor#HAu!iliar# storage

• Cache )emor#


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Dept. of CSE (:

)ain memor#

• 2his is a temporar# memor# $ecause the

data and instructions stored here erased

when the power goes off.

• 2his is also referred as primary memor#.

• It is a semiconductor memor# and

measured in terms of mega$#tes and

giga$#tes.

• It consists of ;A) and ;)


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Dept. of CSE (<

R$" stands for Random $ccess "emory

•It is the read and write memor#.

•2he information stored in this memor# can $e accesseddirectl# without scanning it se/uentiall#.•=ence it is called as random access memor#.•During power failure the information stored in it will $e

erased•It is also called as "olatile memor#.

R%" stands for Read %nly "emory•ermanent memor# and non "olatile.

•2he contents in locations in ;) can not $e changed•It stores mainl# monitor programs and $asic input output

s#stem 6?IS7 programs.


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Dept. of CSE ,*

PR%" Programmable Read %nly "emory• It is a "ariation of ;).

• 2he contents of this memor# are programmed $# the user

• 2hese contents can not $e erased once the# are written toit.

EPR%" : Erasable Programmable Read %nly "emory .

• It is a modification to ;).

• Contents stored can $e erased $# e!posing it to ltraiolet @ight source.

EEPR%": Electrically Erasable Programmable Read %nly"emory

• 2he contents stored in this can $e erased electricall#.


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Dept. of CSE ,1

Secondary Storage !evices

• ?ecause most of main memor# is "olatile and limited5 it

is essential that there should $e other t#pes of storage

de"ices where programs and data can $e stored when

the# are no longer $eing processed

• Secondar# storage de"ices can $e installed within the

computer $o! or added later as needed


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Cache memor#

• It is a =igh speed memor# and placed

$etween the C and the main memor#.

• sers cannot access this memor#.

• It stores the data and instructions currentl#

to $e e!ecuted.

• )ore costlier than main memor#.

• @esser capacit# than main memor#

01class1-2 introduction.ppt

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