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COMPUTER FUNDAMENTALSCOMPUTER FUNDAMENTALS
Basics of computer and its operation:Functional Components and their interconnections
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MELJUN CORTES.MELJUN CORTES.
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSUnderlying Structure
Logical Structure of Digital Computers
SecondaryMemory
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSInput/Output
SecondaryMemory
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSInput/Output
TerminalTerminal
Simpler than a PCSimpler than a PC Designed strictly for input and outputDesigned strictly for input and output
Has keyboard and screenHas keyboard and screen
Does not have a processorDoes not have a processor
Connected to computer with telecommunication lineConnected to computer with telecommunication line
Allows user to key data directly into computerAllows user to key data directly into computer
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSInput/Output
TerminalTerminal
Special types:Special types:
PointPoint--ofof--sale (retail)sale (retail)
ATMs (banking) ATMs (banking)
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSInput/Output Commoninputmethods:Commoninputmethods:
Magnetic ink character recognition (MICR)Magnetic ink character recognition (MICR)
used to process bank checksused to process bank checks Optical character recognition (OCR)Optical character recognition (OCR) directlydirectly
scans typed, printed, or handwritten materialscans typed, printed, or handwritten material
ImagingImaging inputs digital form of documentsinputs digital form of documents
and photosand photos Bar code labelingBar code labeling scans bar codes onscans bar codes on
packages or products, and reads into computerpackages or products, and reads into computer
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMS Common inputmethods:Common inputmethods:
LightPenLightPen A LightPenisa pointing device shapedA LightPenisa pointing device shapedlike a penandisconnectedtoa VDU.like a penandisconnectedtoa VDU.The tipofthe lightpencontainsa lightThe tipofthe lightpencontainsa light--sensitivesensitiveelementwhich, whenplacedagainstthe screen,elementwhich, whenplacedagainstthe screen,detectsthe light fromthe screenenabling thedetectsthe light fromthe screenenabling thecomputer toidentify the locationofthe penonthecomputer toidentify the locationofthe penonthescreen.screen.
Input/Output
http://doit.ort.org/course/input/275.htm
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMS Commoninputmethods:Commoninputmethods:
TouchScreenTouchScreenA TouchSensitive Screenisa pointing deviceA TouchSensitive Screenisa pointing devicethatenablesthe user tointeractwiththe computer by touchingthatenablesthe user tointeractwiththe computer by touching
the screen.the screen.
Input/Output
http://doit.ort.org/course/input/275.htm
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSInput/Output
Commonoutputmethods:Commonoutputmethods:
PrintPrint output to paper using various types ofoutput to paper using various types ofprintersprinters
Computer output microfilm (COM)Computer output microfilm (COM) microfilmmicrofilmgenerated for archive copies in small spacegenerated for archive copies in small space
Voice response unitsVoice response units computer recognizescomputer recognizesinput, generates verbal response messagesinput, generates verbal response messages
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSInput/Output
Multimedia
relatively newterm forcomputerinputand output
in the form oftext, graphics, sound, stillimages,
animations,and/orvideo
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSComputer Memory
SecondaryMemory
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSComputer Memory
MemoryMemory
All data flows to and from memoryAll data flows to and from memory
Divided intoDivided into cellscells::
Each has a unique addressEach has a unique address
Memory cell types:Memory cell types:
ByteByte stores one character of datastores one character of data
WordWord stores two or more characters of datastores two or more characters of data
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Types of MemoryTypes of Memory
P S c o n d
M o
ROM RAM
SRAM DRAMPROM EPROM EAPROM EAPROM
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Primary MemoryPrimary Memory
It is the main or internal memory .It is the main or internal memory .
It can be broadly categorized into twoIt can be broadly categorized into twopartsparts
RAMRAM (Random Access Memory)(Random Access Memory)
ROMROM (Read Only Memory)(Read Only Memory)
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RAMRAM It is known as theIt is known as theRead and WriteRead and Writememorymemory. This memory is. This memory isvolatile.volatile.
Whatever information you store isWhatever information you store istemporarytemporaryin nature and when youin nature and when you
switch off the computer everything isswitch off the computer everything iserased.erased.
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Dynamic RAMDynamic RAM
DynamicDynamic MemoryMemory isis oftenoften referredreferred toto asas volatilevolatilememorymemory..
DataData isis storedstored withinwithin thethe capacitancecapacitance ofof aa
transistortransistor.. TheThe capacitorcapacitor isis unableunable toto preventprevent thethechargecharge fromfrom slowlyslowly dischargingdischarging.. ThisThis wouldwould resultresultinin thethe lossloss ofof datadata.. AA solutionsolution toto thisthis problemproblem isisthethe introductionintroduction ofof additionaladditional circuitrycircuitry whichwhichperformsperforms aa 'memory'memory refresh'refresh' byby periodicallyperiodicallyrestoringrestoring thethe chargecharge..
DynamicDynamic memorymemory isis cheapercheaper thanthan StaticStatic memorymemoryandand isis usedused inin largerlarger memorymemory systemssystems..
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Static RAMStatic RAM
Static memory is moreStatic memory is more expensiveexpensive totoproduce than Dynamic memory, butproduce than Dynamic memory, butbecause of itsbecause of its lower power consumptionlower power consumption itit
is often used in small to medium sizedis often used in small to medium sizedsystems.systems.
Static memoryStatic memory retains dataretains data within a cellwithin a cell
until the data is overwritten or lost as auntil the data is overwritten or lost as aresult of power being shut down.result of power being shut down.
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ROMROMROMROM ItIt isis aa memorymemory unitunit thatthatperformsperforms
thethe ReadRead operationoperation onlyonly andanddoesdoes notnot havehave aa writewrite capabilitycapability..
TheThe BinaryBinary informationinformation inin thetheROMROM isismademade permanent permanent duringduring the the
hardwarehardware productionproduction ofof thethe unitunit andanditit is is not not accessibleaccessible toto usersusers toto storestoreinformationinformation..
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BBASICASIC CCOMPONENTSOMPONENTSOFOF
CCOMPUTEROMPUTER
SSYSTEMSYSTEMS
Computer Files
SecondaryMemory
(Secondary Storage)
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMS
When power is off, everything stored inWhen power is off, everything stored in
memory is lostmemory is lost Computer files are used to store data longComputer files are used to store data long
termterm
File storage devices:File storage devices: Magnetic tape drives, disk drives, floppyMagnetic tape drives, disk drives, floppy
drivesdrives
Optical CD or DVD drivesOptical CD or DVD drives
Computer Files (Secondary Storage)
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMS
Sequential access filesSequential access files
Usually stored on magnetic tape drivesUsually stored on magnetic tape drives
Direct access filesDirect access files
Stored on Direct Access Storage DevicesStored on Direct Access Storage Devices
((DASDDASD)) -- magnetic disk drivesmagnetic disk drives
Computer Files
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMS
Types of DASDTypes of DASD
Fixed (hard) drivesFixed (hard) drives
Computer Files
Figure 2.7 Diagram of a Magnetic Disk Drive
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMS
Types of DASDTypes of DASD
Removable:Removable: Floppy drivesFloppy drives
Zip drivesZip drives
Newest: portableNewest: portable
DASD for PCsDASD for PCs keychain drivekeychain drive
Computer Files
Figure 2.8 Iomegas Mini USB Keychain Drive
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMS Newer type of DASDNewer type of DASD
Optical Disk StorageOptical Disk Storage
CDCD--ROMROM 700700 megabytesmegabytes readread--onlyonly
CDCD--RR recordablerecordable
CDCD--RWRW rewritablerewritable
DVDDVD--ROMROM 44..77 gigabytesgigabytes readread--onlyonly
DVDDVD--RR recordablerecordable
DVDDVD--RWRW rewritablerewritable
Computer Files
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Secondary MemorySecondary Memory
It is theIt is the PermanentPermanentmemory. Thememory. Theinformation stored is permanent ininformation stored is permanent in
nature and it uses external storagenature and it uses external storagedevices likedevices like Floppy disk, Magnetic disk,Floppy disk, Magnetic disk,CDCD--ROM etc.ROM etc.
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Secondary Storage DevicesSecondary Storage Devices
This is a floppy disk!This is a floppy disk!We used it to storeWe used it to storeinformation and itsinformation and its
main advantage ismain advantage isthat it is transportablethat it is transportablebecause of its size.because of its size.
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSBits and Coding Schemes
Each memory cell is a set of circuitsEach memory cell is a set of circuits
Each circuit is on or off (represented byEach circuit is on or off (represented by 11 oror 00)) Each circuit corresponds to aEach circuit corresponds to a bitbit(binary digit)(binary digit)
Most computersMost computers 88 bits (circuits) represents abits (circuits) represents acharacter (character (bytebyte))
22 common bit coding schemes used today:common bit coding schemes used today: ASCIIASCII
EBCDICEBCDIC
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Bits and Coding Schemes
Figure 2.4 Computer Coding Schemes
..
.
..
.
..
.
..
.
..
.
..
.
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BBASICASIC CCOMPONENTSOMPONENTSOFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSArithmetic/Logical Unit
SecondaryMemory
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMS
Consists of VLSI circuitsConsists of VLSI circuitson a silicon chipon a silicon chip
Carries out:Carries out:
arithmeticarithmetic add,add,subtract, multiply, dividesubtract, multiply, divide
logical operationslogical operations
comparing two numberscomparing two numbers
Arithmetic/Logical Unit
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CPUCPU -- Registers (Registers (11 ofof 22))
The CPU also contains aThe CPU also contains asmall high speedsmall high speed
memorymemory which is used towhich is used tostore temporary resultsstore temporary resultsand control information.and control information.
This memory consists ofThis memory consists of
a number ofa number ofregistersregisters,,each performing aeach performing aspecific function.specific function.
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CPUCPU -- Registers (Registers (22 ofof 22))
AccumulatorsAccumulators -- serve the purpose of holding data used inserve the purpose of holding data used incalculations.calculations.
Address RegistersAddress Registers -- are used for storing the memory locationare used for storing the memory locationof data or instructions to be used by a program.of data or instructions to be used by a program.
Stack PointerStack Pointer -- this register is used during subthis register is used during sub--routineroutine
nesting and stack based arithmetic.nesting and stack based arithmetic. Status RegisterStatus Register -- this register provides a service to the CPUthis register provides a service to the CPU
by maintaining the status of the last operation carried out byby maintaining the status of the last operation carried out bythe ALU.the ALU.
Instruction PointerInstruction Pointer -- sometimes referred to as the programsometimes referred to as the program
counter, the pointer is responsible for retaining the memorycounter, the pointer is responsible for retaining the memoryaddress of the next instruction to be executed.address of the next instruction to be executed.
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BBASICASIC CCOMPONENTSOMPONENTS
OFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSControl Unit
SecondaryMemory
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BBASICASIC CCOMPONENTSOMPONENTSOFOF CCOMPUTEROMPUTER SSYSTEMSYSTEMSControl Unit
Controls computer to take advantage of speed andControls computer to take advantage of speed andcapacity of other componentscapacity of other components
Directed by list of operations (program) that tells controlDirected by list of operations (program) that tells control
unit what to dounit what to do decoding the instructions within a computerdecoding the instructions within a computer sequencing the reading and writing of data within thesequencing the reading and writing of data within the
CPU and externally on the data busCPU and externally on the data bus controlling the sequence in which instructions arecontrolling the sequence in which instructions are
executedexecuted controlling the operations performed by the ALUcontrolling the operations performed by the ALU
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TTHEHE SSTOREDTORED--PPROGRAMROGRAM CCONCEPTONCEPT
ProgramProgram list of what computer needs tolist of what computer needs to
do for an applicationdo for an application InstructionInstruction each individual step oreach individual step or
operation in a programoperation in a program
Control unitControl unit carries out one step orcarries out one step orinstruction at a time at electronic speedinstruction at a time at electronic speed
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TTHEHE SSTOREDTORED--PPROGRAMROGRAM CCONCEPTONCEPT
Note:Note: One ofthe primarymeasuresofOne ofthe primarymeasuresofpowerofcomputersisthe numberofpowerofcomputersisthe numberofinstructionsitcanexecute inagiveninstructionsitcanexecute inagiven
periodperiod
MIPS millions ofinstructions persecond
executed bythe controlunit
MFLOPS
millions of floating point operations per
second
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EEXTENSIONS TO THEXTENSIONS TO THE BBASICASICMMODELODELCache Memory
HighHigh--speed storage tospeed storage totemporarily hold data fromtemporarily hold data frommain memory waiting tomain memory waiting to
be processedbe processed Entire blocks of dataEntire blocks of data
moved at one time intomoved at one time intocachecache
Enables CPU to executeEnables CPU to executemuch fastermuch faster
Also incorporated intoAlso incorporated intoDASD controllersDASD controllers
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Cache memoryCache memory Cache memory is random access memory (Cache memory is random access memory (RAMRAM) that a computer) that a computer
microprocessormicroprocessor can access more quickly than it can access regularcan access more quickly than it can access regularRAM. As the microprocessor processes data, it looks first in theRAM. As the microprocessor processes data, it looks first in the cachecachememory and if it finds the data there (from a previous reading ofmemory and if it finds the data there (from a previous reading ofdata), it does not have to do the more timedata), it does not have to do the more time--consuming reading ofconsuming reading ofdata from largerdata from larger memorymemory..
Cache memory is sometimes described in levels of closeness andCache memory is sometimes described in levels of closeness andaccessibility to the microprocessor. Anaccessibility to the microprocessor. An L1L1 cache is on the same chipcache is on the same chipas the microprocessor. (For example, theas the microprocessor. (For example, the PowerPCPowerPC 601 processor has601 processor hasa 32 kilobyte levela 32 kilobyte level--1 cache built into its chip.)1 cache built into its chip.) L2L2 is usually a separateis usually a separatestatic RAMstatic RAM (SRAM(SRAM) chip. The main RAM is usually a dynamic RAM) chip. The main RAM is usually a dynamic RAM((DRAMDRAM) chip.) chip.
Cache that is built into the CPU is faster than separate cache, runningCache that is built into the CPU is faster than separate cache, runningat the speed of theat the speed of the microprocessormicroprocessor itself. However, separate cache isitself. However, separate cache isstill roughly twice as fast as Random Access Memory (RAM). Cache isstill roughly twice as fast as Random Access Memory (RAM). Cache ismore expensive than RAM, but it is well worth getting a CPU andmore expensive than RAM, but it is well worth getting a CPU andmotherboard with builtmotherboard with built--in cache in order to maximize systemin cache in order to maximize systemperformance.performance.
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