computer archtitecture

8/9/2019 Computer Archtitecture

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Mirpur University Of Science and TechnologyMirpur University Of Science and Technology

Submitted By: Saeed Azam, Arslan Asghar,

Faisal Zahoor

Roll No: 04, 01, 31

Class: BS-SE (3rd)Evening

Submitted To: MADAM SEHREEN

Course Title: Computer Architecture


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AcknowledgementAcknowledgement

Every praise is to ALLAH Almighty the kind andmerciful who created the whole universe for us. This isall due to his blessing and miracle that we havesuccessfully crossed another milestone of ouracademic career and completed this study well in timewith great success.

We wish to acknowledge the many people who havehelped to make this report possible, both directly andindirectly.

The people who have helped in over coming all obstacles,large and small, deserve my thanks.

We would like to express deep gratitude toward ourteacher and friends. We owe my deepest gratitude andimmense debt to our families who always prayers forour success and their very kind, moral and financialsupport for execution of our study.


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Summary AbstractSummary Abstract

In this report we discuss about the History of computermemory and give brief explanation about memory ofcomputer.

We choose this problem to improve our knowledge aboutcomputer memory. This research helps us to know the

use of memory in computer.We also discuss the researches made in field of computer

memory to make computer more efficient, helpful andaccurate.

This report is important for those person who are new in the

computer field and also for those who has interest incomputer memory. This report helps them to understandsthe importance of computer memory.


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Table Of Contents:Table Of Contents:Chapter # 1

1.1 History of computer Memory2

1.2 Punched Card 3

1.3 Drum Memory...4

1.4 Konard Zuse..5

1.5 Atanasoff -Berry6

1.6 Jay Forester7

1.7 DRAM...81.8 Apple Computer9

Chapter # 2

2.1 Computer Storage10

2.2 Primary Memory..11

2.3 Main Memory Capacity12

2.4 Secondary Storage.132.5 ROM..14

2.6 PROM15

2.7 EPROM.16

2.8 EEPROM..17

2.9 Mask ROM18


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Chapter # 3

3.1 RAM19

3.2 SRAM..20

3.3 DRAM..21

3.4 FPM..22

3.5 EDO..23

3.6 ECC..24

3.7 SDRAM25

3.8 Hybrid Memory.26

3.9 NVRAM27

3.10 Flash Memory.28

Chapter # 4

4.1 CD-ROM29

4.2 WROM Disk...30

4.3 Floppy Disk.31

4.4 Hard Disk.32Conclusion.33

Recommendation34

Reference....35


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Executive SummaryExecutive Summary

The main objective of making this report is to gainknowledge about computer memory. Its use andimportance in computer.

The background reason that prompts us to gain theknowledge about computer memory is our degree

program of software engineering.The source we use to collect data are the books on

computer of different author like Introduction tocomputers (sixth edition) by Peter Norton andComputer Fundamentals(3rd edition) by PradeepK.Sinha and priti Sinha.

The main thing that we find in our research is that thecomputer memory took central position in solution ofour problems and storing data.


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IntroductionIntroduction

Necessity is the mother of invention. The saying holdstrue for computer memory also because computermemories were invented because of mans searchfor storing large amount of data.

Memory is the lifeblood of many computersmanufactured today. The Operating Systems andother applications created to enhance userexperience and provide instant access to word

processing and Internet browsers require increasingamounts of memory to create the user experience to

which many of us are accustomed.


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Chapter #1Chapter #1

1.1 History Of ComputerMemory:

The history of computer memory is as old ascomputer. The first computers used punchcards for input and had very limited

memory for processing. The averagememory in the first computers wasbetween three and forty five kilobits.Memory was used to store data in theprocessing of linear equations, and theresults were then printed in binary. Whencompared to the computers available

today, the first computers do not seem verytechnologically advanced, but at the timethey were created these first computerswere engineering masterpieces. Many ofthe concepts created when building earlycomputers are still in use in moderncomputing technology.


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1.2 Punched Card:1.2 Punched Card:

In 1834, Charles Babbage begins build his

"Analytical Engine", precursor to the computer.It uses read-only memory in the form of punchcards.

A punched card is a piece of stiff paper that containsdigital information represented by the presenceor absence of holes in predefined positions. Now

almost an obsolete recording medium, punchedcards were widely used throughout the 19thcentury for controlling textile looms and in thelate 19th and early 20th century for operatingfairground organs and related instruments. Theywere used through the 20th century in unit

record machines for input, processing, and datastorage. Early digital computers used punchedcards, often prepared using keypunch machines,as the primary medium for input of bothcomputer programs and data. Some votingmachines use punched cards.


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1.3 Drum Memory:1.3 Drum Memory:

Drum memory is a magnetic data storage device andwas an early form of computer memory widely usedin the 1950s and into the 1960s, invented by GustavTauschek in 1932 in Austria. For many machines, adrum formed the main working memory of themachine, with data and programs being loaded on toor off the drum using media such as paper tape or

punched cards. Drums were so commonly used forthe main working memory that these computerswere often referred to as drum machines. Drumswere later replaced as the main working memory bymemory such as core memory and a variety of othersystems which were faster as they had no moving

parts, and which lasted until semiconductor memoryentered the scene. A drum is a large metal cylinderthat is coated on the outside surface with aferromagnetic recording material. It could beconsidered the precursor to the hard disk platter, butin the form of a drum rather than a flat disk. A row

of read-write heads runs along the long axis of thedrum, one for each track.


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1.4 Konard Zuse:In 1936,Konrad Zuse applies for a

patent for his mechanical memoryto be used in his computer. Thiscomputer memory is based onsliding metal parts.

Konrad Zuse completed the Z3 in 1941.This was the world's first electronic,fully programmable digital

computer based on a binaryfloating-point number and switchingsystem. Zuse used old movie film tostore his programs and data for theZ3, instead of using paper tape orpunched cards.


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1.5 John Atanasoff1.5 John Atanasoff--Berry:Berry:

The Atanasoff-Berry Computer has 60 50-bit words of memory in the form ofcapacitors mounted on two revolvingdrums. For secondary memory it usespunch cards.

The key ideas employed in the ABCincluded binary math and Boolean logic

to solve up to 29 simultaneous linearequations. The ABC had no centralprocessing unit (CPU), but was designedas an electronic device using vacuumtubes for digital computation. It alsoused separate regenerative capacitormemory that operated by a process still

used today in DRAM memory.


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1.6 Jay Forester:1.6 Jay Forester:

Jay Forrester conceives the idea of magneticcore memory as it is to becomecommonly used, with a grid of wiresused to address the cores. The firstpractical form manifests in 1952-53 andrenders obsolete previous types ofcomputer memory.

jay Forrester invented core memory in 1949that became the dominant form ofcomputer memory in the 1950s, andremained in use until the late 1970s.

"A magnetic material can have itsmagnetization altered by an electric

field. If the field isn't strong enough, themagnetism is unchanged. This principlemakes it possible to change a singlepiece of magnetic material -- a smalldoughnut called a core -- wired into agrid, by passing half the current neededto change it through two wires that only

intersect at that core."


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1.7 DRAM:1.7 DRAM:

In 1970, Dr. Robert H. Dennarddinvented the first DRAM (DynamicRandom Access Memory) chip (1Kbit PMOS dynamic RAM ICs), andby 1972 it was the best selling

semiconductor memory chip in theworld, defeating magnetic core typememory. The first commerciallyavailable computer using the 1103was the HP 9800 series.

DRAM needs to be refreshed thousandsof times per second.


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1.8 Apple Computer:1.8 Apple Computer:

On April Fool's Day, 1976, SteveWozniak and Steve Jobs releasedthe Apple I computer and startedApple Computers. The Apple Iwas the first single circuit boardcomputer. It came with a videointerface, 8k of RAM and akeyboard. The systemincorporated some economicalcomponents, including the 6502processor (only $25 dollars -designed by Rockwell andproduced by MOS Technologies)and dynamic RAM.


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Chapter #2Chapter #2

2.1 Computer Storage:The data and instructions, which are entered into the computer system

through input units have to be stored inside the computer, before theactual processing starts. similarly, the results produced by thecomputer after processing ,must also be kept somewhere inside thecomputer system, before being passed on to the output units.

Moreover, the intermediate results produced by the computer, must alsobe preserved for ongoing processing. The storage unit of a computersystem is designed to cater to all these needs. It space for storing dataand instructions, space for intermediate results and space for finalresults.

In short the specific functions of the storage unit are to hold (store):

The data and instructions required for processing (received frominput devices).

Intermediate results of processing.

Final results of processing before these results are released to anoutput device.

The storage unit of all computers is comprised of the following twotypes of storage.


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2.2 Primary Memory:2.2 Primary Memory:

The primary storage is also known as main memory. it isused to hold pieces of program instruction and data,intermediate results of processing and recentlyproduced results of processing ,of the jobs, which thecomputer system is currently working on. These piecesof information are represented electronically in the

main memory chip's circuitry, and while it remains inthe main memory, the central processing unit canaccess it directly at a very fast speed. however theprimary storage can hold information only while thecomputer system is on. As soon as the computer systemis switched off or reset , the information held in the

primary storage disappears.Moreover, the primary storage normally has limited

storage capacity, because it is very expensive .Theprimary storage of modern computer systems is madeup of semiconductor devices.


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2.3 Main Memory Capacity:2.3 Main Memory Capacity:

The main memory capacity of large computer systems isnormally more than that of small systems. This capacity isdefined in term of the number of bytes a computer systemcan store.

Memory capacity of a computer system is normally stated interm of kilobytes (KB),which is equal to 1024(210) bytes of

storage or in term of megabytes (MB), which is equal to1,048,576(220) bytes of storage or in term of gigabytes (GB)which is equal to 1,073,741,824(230) bytes of storage. Noticethat 1KB is about 103bytes, 1MB is about 106bytes and 1GB is about 109bytes, hence the crigin of the prefix kilo(thousand), mega (million) and giga (billion).

1Byte = 8 Bits1024 Bytes = 1 Kilo Bytes (KB)

1024 KB = 1 Mega Bytes (MB)

1024 MB = 1 Giga Bytes (GB)

1024 GB = 1 Tera Bytes (TB)


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2.4 Secondary Storage:2.4 Secondary Storage:

The secondary storage is also known asauxiliary storage. it is used to take care ofthe limitation of the primary storage. thatis, it is used to supplement the limitedstorage capacity and the volatilecharacteristic of primary storage. This is

because secondary storage is muchcheaper than primary storage and it canretain information even when thecomputer system is switched off or reset.The secondary storage is normally used tohold the program instructions, data andinformation of those jobs, on which the

computer system is not working oncurrently, but needs to hold them forprocessing later. The most commonlyused secondary storage medium is themagnetic disk.


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2.5 ROM (Read Only Memory):2.5 ROM (Read Only Memory):

ROM stands for Read Only Memory.I

t is non-volatile memory chip , in which data is storedpermanently and cannot be altered by theprogrammer. In fact storing data permanentlyinto this kind of memory is called burning inthe data", because data in such memory isstored by using fuse links. Once a fuse link isburnt it is permanent. The data stored in ROMchip can only be read and used-they cannot bechanged. This is the reason why it is calledread-only memory. since ROM chips are non-volatile , the data stored inside a ROM are notlost, when the power supply is switched off,unlike the case of a volatile RAM chip.ROMs are also known as field stores,permanent stores. ROMs are used to storecritical program such as the program thatboots the computer.

There are various types of ROM some areexplained ahead.


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2.6 PROM (Programmable Read Only Memory):2.6 PROM (Programmable Read Only Memory):

PROM stands for ProgrammableRead Only Memory. PROM is amemory chip on which data canbe written only once. Once aprogram has been written onto aPROM, it remains their for ever.Unlike RAM, PROM retains theircontents. when the computer iseven turned off. The differencebetween PROM and ROM is that,a PROM is programmed during

the manufacturing process. Towrite data onto a PROM chipyou need a special device called aPROM programmer or PROMBurner. The process ofprogramming a PROM is some

time called Burning PROM.


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2.7 EPROM (Erasable programmable ROM)2.7 EPROM (Erasable programmable ROM)EPROM stands for Erasable programmable Read Only

Memory. Once information is stored in a ROM chipor a PROM chip , it cannot be altered. However,there is another type of memory chip, calledEPROM, which overcomes this problem. As thename implies, it is possible to erase informationstored in an EPROM chip and the chip can bereprogrammed to store new information. EPROMs

are often used by R&D personnel (experimenters),who frequently change the micro programs to testthe efficiency of the computer system with newprograms. EPROMs are also useful in case of thoseapplication where one may like to store a programin a ROM, which would normally not change butunder some unforeseen conditions one may like to

alter it. When an EPROM is in use informationstored in it can only be read and the informationremains in the chip until it is erased.

The information stored in EPROM is erased byexposing the chip for some time to ultraviolet light .It is also known as Ultra Violet EPROM(UVEPROM). once a program has been erased itcan be reprogrammed.


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2.8 EEPROM (Electrical Erasable PROM):2.8 EEPROM (Electrical Erasable PROM):

It stands for Electrical ErasableProgrammable Read Only Memory. Itis non-volatile memory. It is writable.It is fast to read but slow to erase andwrite. EEPROM is a special type ofPROM , that can be erased byexposing it to an Electrical charge.Like other types of PROM, EEPROMretains contents even when the poweris turned off. EEPROM is similar toflash memory some time called flash

EEPROM. The major difference isthat EEPROM required data to bewritten or erased one byte at a time,where flash memory allows data to bewritten or erased in a blocks. Thismakes flash memory faster.


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2.9 Mask ROM:2.9 Mask ROM:

Mask ROM is type of Read OnlyMemory whose contents areprogrammed by the integratedcircuit manufacture ratherthan a user. The terminologymask come from ICsfabrication where the regionof the chip is masked off.

ROM manufactures usually

impose a mask charge ofseveral thousand dollars thatis why mask ROMs arenormally use today only inhigh volume application. Forlow level volume applicationthere are more cost effectivechoices.


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3.1 RAM (Random Access Memory):3.1 RAM (Random Access Memory):

RAM stands for Random Access Memory. Data can be

read or written to RAM without any special voltageor light source. A data word in the memory istypically read or written one word at a time afterselecting the address of it . However the data storedin the RAM is lost if the power to the IC chip isdisconnected. This mean that RAM is volatilememory. RAM is usually used for primary storage in

computer to hold active information such as data andprograms.

This memory consists of some integrated circuit eitheron the motherboard or on a small circuit boardattached to the motherboard. A computer'smotherboard is designed in a manner that its

memory capacity can be easily enhanced by addingmore memory chips. Hence if you decide to havemore memory than your computer currently has, youcan plug them in the empty memory slots on themotherboard. The additional RAM chips, whichplug into special sockets on the motherboard, arealso known as single in-line modules (SIMMs).

There are two types of RAM which are explainedahead.

CHAPTER # 3


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3.2 SRAM (Static Random Access Memory):3.2 SRAM (Static Random Access Memory):

SRAM stands for static RandomAccess Memory. Static RandomAccess Memory (SRAM) is a typeof semiconductor memory wherethe word static indicates that,unlike dynamic RAM (DRAM), itdoes not need to be periodicallyrefreshed. SRAM exhibits dataremanence but is still volatile inthe conventional sense that data iseventually lost when the memory

is not powered. The informationremains stored as long as thepower is applied to the chip.Unless some location is writtenagain.


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3.3 DRAM (Dynamic Random Access Memory):3.3 DRAM (Dynamic Random Access Memory):

DRAM stands for Dynamic Random AccessMemory. Dynamic random access memory(DRAM) is a type of random access memorythat stores each bit of data in a separatecapacitor within an integrated circuit.Thedata stored at each location must beperiodically refreshed by reading it andwriting it back again or otherwise itdisappeared.

The advantage of DRAM is its structuralsimplicity. only one transistor and a capacitorare required per bit, compared to sixtransistors in SRAM. This allows DRAM to

reach very high density. Unlike flashmemory, it is volatile memory . since it losesits data when the power supply is removed.The transistors and capacitors used areextremely smallmillions can fit on a singlememory chip.

DRAM is the cheapest to build.Newer and fasterDynamic RAM types are develop

continously . Currently there are four typesof DRAM.


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3.4 FPM (Fast Page Mode):3.4 FPM (Fast Page Mode):

FPM stands for Fast Page Mode.It is slightly faster thanconventional DRAM. Whilestandard DRAM requires thata row and column be sent for

each access. FPM works bysending the row address justonce for many accesses tomemory in location near eachother improving access time.FPM memory itself is an

improved version of itspredecessor page modememory, which is very rarelyseen now. Despite its name(Fast Page Mode). FPM isactually the slowest memory

technology used in modernPCs.


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3.5 EDO (Extended Data Output):3.5 EDO (Extended Data Output):

EDO stands for Extended Data Output.sometime it is also called hyperpage mode DRAM. It is slightlyfaster than FPM memory due toanother evolutionary tweak in howthe memory access works. Insimplified term EDO memory hashad its timing circuit modified . Soone access to the memory canbegin before the last one hasfinished. It is therefore slightly

faster than FPM memory.EDO memory costs the same amount

to manufacture as FPM and due toit prominence in the market now ischeapest than FPM despite beingnewer and faster.


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3.6 ECC (Error Correcting Code):3.6 ECC (Error Correcting Code):

ECC stands for Error correctingcode. It is memory that is ableto detect and correct someSDRAM errors without userintervention. ECC SDRAMreplaced parity memory whichcould only detect but do notcorrect SDRAM error. MostECC SDRAM can correctsingle bit errors and detect but

not correct larger errors. Thuserrors greater in size than onebit will still crash computer.


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3.7 SDRAM (Synchronous DRAM):3.7 SDRAM (Synchronous DRAM):

SDRAM stands for Synchronous DRAM. Arelatively new and different kind of RAM,Synchronous DRAM differs from earliertypes in that it does not run a Synchronous tothe system clock the way older, conventional

types of memory do. SDRAM is tied to thesystem clock and is designed to be able toread or write from memory in burst mode at 1clock per access at memory bus speed up to100 MHz or even higher.

SDRAM is rapidly becoming the new memorystandard for modern PCs .The reason is that it

is Synchronized design permits support forthe much higher bus speed that have started toenter the market.

As 100 MHz bus system PCs becomemainstream ,SDRAM will largely replaceolder technologies since it is designed to workat these higher operating speeds andconventional asynchronous DRAM is not.


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3.8 Hybrid Memory:3.8 Hybrid Memory:

A hybrid drive is a type of a largebuffer computer hard diskdrive. It is different fromstandard hard drive in that ituses a smaller solid state drive

(SSD) as a cache. The cachetypically uses non-volatileRAM. The flash memorybuffer can speed up replacedreads, a RAM buffer speedsboth reads and writes but

must be written to backupstorage when power is lost.The various types of hybridmemory are:


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3.9 NVRAM:3.9 NVRAM:

NVRAM stands for Non-Volatile RandomAccess Memory. It is the general name usedto describe any type of Random AccessMemory which does not lose its informationwhen power is turned off. This is in contrastto the most common forms of RandomAccess Memory. DRAM and SRAM whichboth require continual power in order tomaintain their data.

NVRAM is a group of the more general class ofnon-volatile memory types, the differencebeing that NVRAM devices offer RandomAccess unlike hard disk.

The best known form of NVRAM memory isflash memory. Some drawbacks to flashmemory include the requirement to write it inlarger blocks than many computers canautomatically address and the relativelylimited longevity of flash memory due to itsfinite number of write erase cycles.


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3.10 Flash Memory:3.10 Flash Memory:

Flash Memory is a non-volatile computer storagethat can be electrically erased andreprogrammed. It is a technology that isprimarily used in memory cards and USB flashdrivers for general storage and transfer of databetween computers and other digital products.It is a specific type of EEPROM that is erasedand programmed in large blocks, in early flashthe entire chip had to be erased at once. Flashmemory costs far less than byte programmableEEPROM and therefore has become thedominant technology wherever a significantamount of non-volatile, solid state storage isneed.

Since flash memory is non-volatile , no power isneeded to maintain the information stored inthe chip. In addition flash memory offers fastread access time and better kinetic shockresistance than hard disk.

The most common secondary storage devices are:


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4.1 CD4.1 CD--ROM:ROM:

CD-ROM stands for Compact Disk-ReadOnly Memory. It is a spin-off musicCD technology and works much likethe music CDs used in music system.In fact, if you have a soundboard and

speakers connected to your computer,you can play music CDs with yourcomputer.

The CD-ROM disk is a shiny, silvercolor metal disk 12cm diameter. Ithas a storage capacity of about 650

Megabytes. It is so called,because ofits enormous storage capacity on acompact-size disk, and because it is aread-only storage medium. That is,these disks come pre-recorded andthe information stored on them

cannot be altered.

CHAPTER # 4


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4.2 WORM Disk:4.2 WORM Disk:

WORM stands for Write-Once, read many.WORM disks allow the users to createtheir own CD-ROM disks by using a CD-recordable (CD-R) drive, which can beattached to a computer as a regular

peripheral device. WORM disks , whichlook like standard CD-ROM disks, arepurchased blank and encoded using aCD-R drive. The information recorded ona WORM disk by a CD-R drive can beread by ordinary CD-ROM drive. As the

name implies, data can be written onlyonce on WORM disk but can be readmany times. That is, as with a CD-ROMonce data has been etched on to thesurface of a WORM disk, it becomespermanent, which can be read but neveraltered.


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4.3 Floppy Disks:4.3 Floppy Disks:

A floppy disk is a round, flat piece offlexible plastic, coated with magneticoxide. It is encased in a square plasticor vinyl cover. The jacket giveshandling protection to the disk surface.

Moreover it has a special liner, whichprovides a wiping action to removedust particles, which are harmful forthe disk surface and the read/writehead. Floppy disks are so calledbecause they are made of flexible

plastic plates, which can bend, not hardplates.

They are also known as floppies ordiskettes. They were introduced byIBM in 1972, and are now beingproduced in various sizes and

capacities by many manufacturers.


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4.4 Hard Disk:4.4 Hard Disk:

A hard disk is a sealed unit that a PCuses for non-volatile data storage.It is secondary storage device. It isalso called permanent storagedevice. It is main location where

all data is stored. Data can beaccess directly. Data recordingtime is faster in this category ofcomputer memory.

Hard disk consist on thin, circularmetal plate/platter coated on bothside with magnetic oxide. more

than one plates/platters are arrangevertically after one and other.Most hard disk have 2-4 platters.

A typical platters stores data on bothsides and has 80 tracks on eachside. Each track has sectors. Asector is capable of holding 512bytes of data.


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References:References:

All the references and source from where data gathered for this report arementioned herewith for your kind concern.

Books

1.Introduction to Computer 6th edition

By PETER NORTON

2.Computer Fundamentals 3rd Edition

By Pradeep K.Sinha and Priti Sinha

INTERNET

www.about.com

www.answer.com

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