UNITI:OVERVIEW

Agenda•  GeneralOrganiza/onandarchitecture•  Structural/func/onalviewofacomputer•  Evolu/on/briefhistoryofcomputer.

Architecture&Organiza/on•  ComputerArchitectureisthoseaBributesvisibletotheprogrammer

or those aBributes that have a direct impact on the logical execu/on of aprogram—  Instruc/on set, number of bits used for data representa/on, I/O

mechanisms,addressingtechniques.— e.g.Isthereamul/plyinstruc/on?

•  Computer Organiza<on refers to the opera/onal units & theirinterconnec/ons that realize thearchitectural specifica/ons.Basically, itisabouthowfeaturesareimplemented.— Controlsignals,interfaces,memorytechnology.— e.g. Is there a hardware mul/ply unit or is it done by repeated

addi/on?

Structure&Func/on•  Structureisthewayinwhichcomponentsrelatetoeachother•  Func/on is the opera/on of individual components as part of the

structure

Func/on•  Allcomputerfunc/onsare:

— Dataprocessing:Processdata— Datastorage:Storedata— Datamovement:Movedatabetweenitself&outsideworld.

Whendataarereceivedfromordeliveredtoadevicethatisdirectlyconnected to the computer, the process is known as I/O and thedeviceisknownasperipheral.When data are moved to or from a remote device, the process isknownasdatacommunica/ons.

— Control: Controls the above three func/ons by an individual whoprovidesthecomputerwithinstruc/ons.

Func/onalview

A Functional View of the Computer

Opera/ons(1)Datamovement

Transferringdatafromoneperipheralorcommunica/onlinetoanother.e.g.CameraaBachedtoaPC,sendingtheframestoawindowonthescreenofthesamePC.

Opera/ons(2)Storage

Data transferred from the external environmenttocomputerstorage&vice-versa.e.g. Playing an mp3 file stored in memory toearphonesaBachedtothesamePC.

Opera/on(3)Processingfrom/tostorage

Dataprocessingondatainstorage.e.g. Any number-crunching applica/on thattakesdatafrommemoryandstorestheresultbackinmemory

Opera/on(4)ProcessingfromstoragetoI/O

Data processing on data en-route betweenstorage&externalenvironment.e.g. Receiving packets over a networkinterface, verifying their CRC, then storingtheminmemory.

Structure-TopLevel

Computer

Main Memory

Input Output

Systems Interconnection

Peripherals

Communication lines

Central Processing Unit

Computer

Storesdata

Movesdatabetweencomputer&itsexternalenvironment

Mechanismthatprovidesforcommunica/onamongCPU,mainmemory&I/O.e.g.systembus

Controlstheopera/onofcomputer&performsitsdataprocessingfunc/ons.

Structure-TheCPU

Computer Arithmetic and Login Unit

Control Unit

Internal CPU Interconnection

Registers

CPU

I/O

Memory

System Bus

CPU

Controlstheopera/onofCPU

Performscomputer�sdataprocessingfunc/ons

ProvidesstorageinternaltoCPU

Mechanismthatprovidesforcommunica/onamongCU,ALU&registers

Structure-TheControlUnit

CPU

Control Memory

Control Unit Registers and Decoders

Sequencing Login

Control Unit

ALU

Registers

Internal Bus

Control Unit

Evolu/onofComputersFIRSTGENERATION(1945–1955)•  Programanddataresideinthesamememory(storedprogramconcepts–

JohnvonNeumann)•  ALPwasmadeusedtowriteprograms•  Vacuumtubeswereusedtoimplementthefunc/ons(ALU&CUdesign)•  Magne/ccoreandmagne/ctapestoragedevicesareused•  Usingelectronicvacuumtubes,astheswitchingcomponents

SECONDGENERATION(1955–1965)•  TransistorwereusedtodesignALU&CU•  HLLisused(FORTRAN)•  ToconvertHLLtoMLLcompilerwereused•  Separate I/Oprocessorweredeveloped tooperate inparallelwithCPU,

thusimprovingtheperformance•  Inven/on of the transistor which was faster, smaller and required

considerablylesspowertooperate

THIRDGENERATION(1965-1975)•  ICtechnologyimproved•  Improved IC technology helped in designing low cost, high speed

processorandmemorymodules•  Mul/programming,pipeliningconceptswereincorporated•  DOSallowedefficientandcoordinateopera/onofcomputersystemwith

mul/pleusers•  Cacheandvirtualmemoryconceptsweredeveloped•  Morethanonecircuitonasinglesiliconchipbecameavailable

FOURTHGENERATION(1975-1985)•  CPU–Termedasmicroprocessor•  INTEL,MOTOROLA,TEXAS,NATIONALsemiconductorsstarteddeveloping

microprocessor•  Worksta/ons, microprocessor (PC) & Notebook computers were

developed•  Interconnec/on of different computer for beBer communica/on

LAN,MAN,WAN•  Computa/onalspeedincreasedby1000/mes•  SpecializedprocessorslikeDigitalSignalProcessorwerealsodeveloped

BEYONDTHEFOURTHGENERATION(1985–TILLDATE)•  E-Commerce,E-banking,homeoffice•  ARM,AMD,INTEL,MOTOROLA•  Highspeedprocessor-GHzspeed•  BecauseofsubmicronICtechnologylotofaddedfeaturesinsmallsize