Lecture 01 & 02 - what is computer & its types

Introduction To Computer Science

1. Basic Computer

2. What is Computer
•Acomputerisnotanacronymandsometimesabbreviatedascompor'puter.Theterm
"computer"wasoriginallygiventohumanswhoperformednumericalcalculationsusing
mechanicalcalculators,suchastheabacusandsliderule.Thetermwaslatergiventoa
mechanicaldeviceastheybeganreplacingthehumancomputers.Today'scomputersare
electronicdevicesthatacceptdata(input),processthatdata,produceoutput,andthen
store(storage)theresults.
•ComputerisanelectronicdevicethatisdesignedtoworkwithInformation.Theterm
computerisderivedfromtheLatinterm‘computare’,thismeanstocalculate.Computer
cannotdoanythingwithoutaProgram.itrepresentsthedecimalnumbersthrougha
stringofbinarydigits.TheWord'Computer‘usuallyreferstotheCenterProcessorUnit
plusInternalmemory.

3. Types of Computer
•Desktop computers
Desktopcomputersaredesignedfor
useatadeskortable.Theyare
typicallylargerandmorepowerful
thanothertypesofpersonalcomputers.
Desktopcomputersaremadeupof
separatecomponents.Themain
component,calledthesystemunit,is
usuallyarectangularcasethatsitson
orunderneathadesk.Other
components,suchasthemonitor,
mouse,andkeyboard,connecttothe
systemunit.

4. Types of Computer
Laptops and netbooks
•LaptopsarelightweightmobilePCswitha
thinscreen.Laptopscanoperateon
batteries,soyoucantakethemanywhere.
Unlikedesktops,laptopscombinethe
CPU,screen,andkeyboardinasingle
case.Thescreenfoldsdownontothe
keyboardwhennotinuse.
•Netbooks(alsoreferredtoasmini
notebooks),aresmall,affordablelaptops
thataredesignedtoperformalimited
numberoftasks.They'reusuallyless
powerfulthanlaptops,sothey'reused
mainlytobrowsethewebandcheck
e-mail.

5. Types of Computer
Smartphones
•Smartphonesaremobilephonesthathave
someofthesamecapabilitiesasacomputer.
Youcanuseasmartphonetomaketelephone
calls,accesstheInternet,organizecontact
information,sende-mailandtextmessages,
playgames,andtakepictures.Smartphones
usuallyhaveakeyboardandalargescreen.

6. Types of Computer
Handheld computers
•Handheldcomputers,alsocalledpersonal
digitalassistants(PDAs),arebattery-powered
computerssmallenoughtocarryalmost
anywhere.Althoughnotaspowerfulas
desktopsorlaptops,handheldcomputersare
usefulforschedulingappointments,storing
addressesandphonenumbers,andplaying
games.Somehavemoreadvanced
capabilities,suchasmakingtelephonecallsor
accessingtheInternet.Insteadofkeyboards,
handheldcomputershavetouchscreensthat
youusewithyourfingerorastylus(apen-
shapedpointingtool).

7. Types of Computer
Tablet PCs
•TabletPCsaremobilePCsthatcombine
featuresoflaptopsandhandheldcomputers.
Likelaptops,they'repowerfulandhavea
built-inscreen.Likehandheldcomputers,
theyallowyoutowritenotesordraw
picturesonthescreen,usuallywithatablet
peninsteadofastylus.Theycanalsoconvert
yourhandwritingintotypedtext.Some
TabletPCsare“convertibles”withascreen
thatswivelsandunfoldstorevealakeyboard
underneath.

8. Types of Computer
SuperComputers
•Themostpowerfulcomputersintermsof
performanceanddataprocessingarethe
supercomputers.Thesearespecializedandtask
specificcomputersusedbylargeorganizations.These
computersareusedforresearchandexploration
purposes,likeNASAusessupercomputersfor
launchingspaceshuttles,controllingthemandfor
spaceexplorationpurpose.
•Thesupercomputersareveryexpensiveandvery
largeinsize.Itcanbeaccommodatedinlargeair-
conditionedrooms;somesupercomputerscanspan
anentirebuilding.“In1964,Seymourcraydesigned
thefirstsupercomputerCDC6600”

9. Types of Computer
Uses of Supercomputer
•InPakistanandothercountriesSupercomputersareusedbyEducationalInstituteslike
NUST(Pakistan)forresearchpurposes.PakistanAtomicEnergycommission&Heavy
IndustryTaxilausessupercomputersforResearchpurposes.
Space Exploration
•Supercomputersareusedtostudytheoriginoftheuniverse,thedark-matters.Forthese
studiesscientistuseIBM’spowerfulsupercomputer“Roadrunner”atNationalLaboratory
LosAlamos.
Earthquake studies
•SupercomputersareusedtostudytheEarthquakesphenomenon.Besidesthat
supercomputersareusedfornaturalresourcesexploration,likenaturalgas,petroleum,
coal,etc.

10. Types of Computer
Uses of Supercomputer (Cont)
Weather Forecasting
•Supercomputersareusedforweatherforecasting,andtostudythenatureandextentof
Hurricanes,Rainfalls,windstorms,etc.
Nuclear weapons testing
•SupercomputersareusedtorunweaponsimulationthatcantesttheRange,accuracy&impactof
Nuclearweapons.
Popular Supercomputers
•IBM’s Sequoia, in United States
•Fujitsu’s K Computer in Japan
•IBM’s Mira in United States
•IBM’s SuperMUC in Germany
•NUDT Tianhe-1A in China

11. Types of Computer
ServersComputers
•Serversareastepundersupercomputers,becausethey
don'tfocusontryingtosolveoneverycomplexproblem,
buttrytosolvemanysimilarsmallerones.Anexampleof
aserverwouldbethecomputersthatWikipediastoresits
encyclopediaon.Thosecomputershavetogoandfindthe
pageyou'relookingforandsendittoyou.Initselfit'snot
abigtask,butitbecomesajobforaserverwhenthe
computershavetogoandfindlotsofpagesforalotof
peopleandsendthemtotherightplace.Someservers,like
theonesGoogleusesforsomethinglikeGoogle
Documents,haveapplicationsontheminsteadofjust
files,likeWikipedia.
•Aserverisacentralcomputerthatcontainscollectionsof
dataandprograms.Alsocalledanetworkserver,this
systemallowsallconnecteduserstoshareandstore
electronicdataandapplications.Twoimportanttypesof
serversarefileserversandapplicationservers.

12. Types of Computer
Mainframe computer
•AlthoughMainframesarenotaspowerfulas
supercomputers,butcertainlytheyarequite
expensivenonetheless,andmanylargefirms&
governmentorganizationsusesMainframestorun
theirbusinessoperations.TheMainframecomputers
canbeaccommodatedinlargeair-conditioned
roomsbecauseofitssize.Super-computersarethe
fastestcomputerswithlargedatastoragecapacity,
Mainframescanalsoprocess&storelargeamount
ofdata.Bankseducationalinstitutions&insurance
companiesusemainframecomputerstostoredata
abouttheircustomers,students&insurancepolicy
holders.
Fujitsu’s ICL VME
Hitachi’s Z800

13. Types of Computer
Game consoles
Agameconsoleisaspecializedkindof
computerthatisusedforplayingvideogames.
Althoughtheyarenotasfullyfeaturedas
desktopcomputers,manynewerconsoles,such
astheNintendoWii&PS3,4,allowyouto
performnongamingtaskslikebrowsingthe
Web.