Download - CSC1100 - Chapter05 - Storage
Discovering Computers 2008
Chapter 5 Chapter 5 Chapter 5 Chapter 5
StorageStorageStorageStorage
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Chapter 5 ObjectivesChapter 5 ObjectivesChapter 5 ObjectivesChapter 5 Objectives
Differentiate between storage devicesand storage media
Differentiate between storage devicesand storage media
Describe the characteristics ofmagnetic disks
Describe the characteristics ofmagnetic disks
Describe the characteristics of Describe the characteristics of
Differentiate among CD-ROMs,recordable CDs, rewritable CDs,
DVD-ROMs, BD-ROMs, HD DVD-ROMs, recordable DVDs, and
rewritable DVDs
Differentiate among CD-ROMs,recordable CDs, rewritable CDs,
DVD-ROMs, BD-ROMs, HD DVD-ROMs, recordable DVDs, and
rewritable DVDs
Identify the uses of tapeIdentify the uses of tapeDescribe the characteristics of a hard disk
Describe the characteristics of a hard disk
Discuss various types of miniature, external, and removable hard disksDiscuss various types of miniature, external, and removable hard disks
Describe the characteristics of optical discs
Describe the characteristics of optical discs
Identify the uses of tapeIdentify the uses of tape
Discuss PC Cards, ExpressCard modules, and the various types of
miniature storage media
Discuss PC Cards, ExpressCard modules, and the various types of
miniature storage media
Identify uses of microfilm and microfiche
Identify uses of microfilm and microfiche
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Learning OutcomeLearning OutcomeLearning OutcomeLearning Outcome
Successful students will be able to:
Describe the characteristics of computer hardware devices and explain their functionalities.
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StorageStorageStorageStorage
What is storage?� Holds data, instructions, and information for future use� Storage mediumis physical material used for storage
� Also called secondary storage
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StorageStorageStorageStorage
What is capacity?
Kilobyte (KB) 1 thousand
Megabyte (MB) 1 million
Gigabyte (GB) 1 billion
� Number of bytes (characters) a storage medium can hold
Gigabyte (GB) 1 billion
Terabyte (TB) 1 trillion
Petabyte (PB) 1 quadrillion
Exabyte (EB) 1 quintillion
Zettabyte (ZB) 1 sextillion
Yottabyte (YB) 1 septillion
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StorageStorageStorageStorage
How does volatility compare?� Storage medium is nonvolatile—contents retained when
power is off
ON OFF
� Memory is volatile—holds data and instructions temporarily
Storage Medium(floppy disks, Zip disks,
hard disks, CDs)No
nvo
lati
le
Contents Contents retainedretained
Contents Contents available to useravailable to user
Memory(most RAM)
(chips on motherboard)
Screen Display
Vola
tile Display Display
disappearsdisappears
Data andData andinstructions instructions
available to useravailable to user
Display Display appearsappears
Data and Data and instructions erasedinstructions erased
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WritingWritingProcess of transferring Process of transferring
WritingWritingProcess of transferring Process of transferring
StorageStorageStorageStorage
What is a storage device?
ReadingReadingProcess of transferring Process of transferring
ReadingReadingProcess of transferring Process of transferring
Hardware that Hardware that records and records and
retrieves items retrieves items Process of transferring Process of transferring items from memory items from memory
to storage mediato storage media
Process of transferring Process of transferring items from memory items from memory
to storage mediato storage media
Process of transferring Process of transferring items from storage items from storage media to memorymedia to memory
Process of transferring Process of transferring items from storage items from storage media to memorymedia to memory
to and from to and from storage mediastorage media
Functions as source of input
Creates output
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Primary Storage
Items waiting to be interpretedand executedby the processor
Memory (most RAM)
Stores …Transfer rates
StorageStorageStorageStorage
What is access time?� Time it takes storage device to locate item on storage medium� Time required to deliver item from memory to processor
fastertransfer
rates
Floppy Disk Small filesto be transported
Secondary Storage
Hard Disk
Flash Memory Cards and USB Flash Drives
CDs and DVDs
Tape
and executedby the processor
Operating system, applicationsoftware, user data and informationDigital pictures or filesto be transported
Software, backups, movies, music
Backupsslowertransfer
rates
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Access time & Transfer rateAccess time & Transfer rateAccess time & Transfer rateAccess time & Transfer rate
Memory accesses items in billionths of a second (nanoseconds)
Storage devicesaccess items in:� thousandths of a second (milliseconds) or
millionths of a second (microseconds)� millionths of a second (microseconds)
Transfer rate is the speed with which data, instruction & info transfer to & from a device, stated as:� KBps & MBps
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
� Use magnetic particles to store items on a disk’s surface
� Alignment of magnetic particles represents the data – either a 0 bit or a 1 bit
� Must be formatted first:Must be formatted first:� Dividing the disk into tracks & sectors, so the OS can
store & locate items on disk
� A sector stores up to 512 bytes of data
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
Trackis narrow
recording bandthat forms fullcircle on disk
Sectorstores up to512 bytesof data
Formatting prepares disk for use
circle on disk of data
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
� For reading & writing purpose, sectors (2-8, depending on OS) are grouped into clusters
� Cluster (allocation unit) is the smallest unit of disk space that stores an item
� Each cluster holds data from only one fileEach cluster holds data from only one file� Even if a file consists of only few bytes, it uses an
entire cluster� One file, anyhow, can span many clusters
� Sometimes, a sector has defect & cannot store data. When format, OS marks these bad sectors as unusable
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What is ahard disk/hard disk drive/hard drive ?hard disk mounted
in system unit
� High-capacity storage: 80 – 750GB & more
� Consists of several inflexible, circular platters that store items electronically
� Components enclosed in airtight,
Perpendicular recording
� Components enclosed in airtight, sealed casefor protection
Longitudinal recording
Fixed h/d & portable h/d
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What are characteristics of a hard disk?
Sample Hard Disk Characteristics
Advertised capacity 500 GB
Platters 4
Read/write heads 8
Cylinders 16,383Cylinders 16,383
Bytes per second 512
Sectors per track 63
Sectors per drive 973,773,168
Revolutions per minute 7,200
Transfer rate 300 MB per second
Access time 8.5 ms
actualdisk
capacity
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
� h/d capacity determined from num of plattersand composition of magnetic coatingon the platters
� Platter� diameter: 3.5 inches in– desktop; 2.5 inches – notebook &
mobile devices� made of aluminum, glass or ceramic– coated with alloy–� made of aluminum, glass or ceramic– coated with alloy–
allow items to be recorded magnetically on its surface. The coating is 3 millionths of an inchthick
� Each has 2 read/write heads, one for each side
� h/d armsmove read/write heads to the proper location –read & write items in the drive as it barely touches the disk/s recording surface
� Location of read/write heads referred to by its cylinder– a vertical section of a track that passes through all platters
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
How does a hard disk work?
Step 2.Small motor spins
Step 3.When software requests a disk access, read/write heads determine current or new location of data.
Step 1.Circuit board controls movement of head actuator and a small motor.
Small motor spins platters while computer is running.
Step 4.Head actuator positions read/write head arms over correct location on platters to read or write data.
platters rotate at high speed: 5400 – 15000 revolutions per minute (rpm)– until power is removed
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What is acylinder?� Vertical section of
track through all platters
� Single movement of read/write head arms accesses all
plattertrack
sector
arms accesses all plattersin cylinder read/write
head
platter
sides
cylinder
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What is ahead crash?
� Spinning creates cushion of air that floats read/write head above platter� Occurs when read/write head touches platter surface
� A smoke particle, dust particle, or human hair could render drive unusable� Clearance between head and platter is approximately two-millionths of an inch
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What is a disk cache/buffer?� Portion of memory
(memory chip on h/d) that processor uses to store frequently accessed items
� 2MB – 16MB (the greater, the faster the (the greater, the faster the h/d)
secondrequestfor data—to hard disk
first requestfor data—to disk cache
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What is RAID ?� Redundant Array of Independent Disks� Connects multiple smaller disks into a single unit that
acts as a single large hard disk
What is backup?What is backup?� A duplicate of a file, program or diskplaced on a
separate storage medium that user can use in case the original is lost, damaged or destroyed
What is density?� Number of bits in an area on a storage medium� High density = high capacity
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Backup methodBackup methodBackup methodBackup method---- Hard DisksHard DisksHard DisksHard Disks
How does RAID work?Disk system that duplicates data, instructions, and information to improve data reliability
� Mirroring has one backup disk for each disk� Striping stores data across multiple disks
mirroring(RAID Level 1)
striping
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What is a miniature hard disk?� Provide greater storage capacities than flash memory:
4GB – 160GB– mostly use perpendicular recording� Smaller than notebook computer hard disks� A pocket hard drive is a self-contained unit
� User can insert in & remove from a slot in a device or � User can insert in & remove from a slot in a device or a computer or plug-in a USB port on a computer
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What are external hard disksand removable hard disks?
External hard disk—freestandinghard disk that connects to system unit
Removable hard disk—hard diskthat you insert and removefrom hard disk drive
� Used to back up or transfer files
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External & Removable Hard DiskExternal & Removable Hard DiskExternal & Removable Hard DiskExternal & Removable Hard Disk
External h/d:�Connects with cable to USB or FireWire port on SU�Some include multiple h/d act as one, having capacity up to 1TB
Removable h/d:�Sometimes the drive is built in the SU�Sometimes the drive is built in the SU�Others are external devices – connect with cable to USB or
FireWire port on SU.�Has up to 500GB capacity
ADVANTAGES??
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SATASATA (Serial Advanced Serial Advanced Technology AttachmentTechnology Attachment) controller ) controller uses serial signals to transfer data, uses serial signals to transfer data,
Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What is a disk controller?
Chip and circuits Chip and circuits that control transfer that control transfer of items from diskof items from disk
SCSISCSIcontroller supports up to fifteencontroller supports up to fifteendevices including hard disks, CDdevices including hard disks, CD
and DVD drives, tape drives, printers,and DVD drives, tape drives, printers,scanners, network cardsscanners, network cards
uses serial signals to transfer data, uses serial signals to transfer data, instructions, and informationinstructions, and information
EIDEEIDE (EEnhancednhancedII ntegratedntegratedDDrive rive EElectronics) controller supports four lectronics) controller supports four hard disks, provides connections for hard disks, provides connections for
CD and DVD drivesCD and DVD drives
of items from diskof items from disk
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What is online storage?� Service on Webthat provides storage for
minimal monthly fee� Files can be accessed from
any computer with Web access
� Large files can be downloaded
� Others can be authorized to access your data
Large files can be downloaded instantaneously
REASONS??
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
What is a floppy disk?� Portable, inexpensive storage medium
(also called diskette)� Consists of thin, circular, flexible plastic
Mylar film with magnetic coating� Enclosed in 3.5” wide plastic shell
Storage capacity: 1.44MB� Storage capacity: 1.44MB� Access time: 84 ms� Transfer rate: 250 – 500KBps� Contains 80 track on each side� ≈ 18 sectors per track
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Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
shutter
liner
metal
shellmagnetic coating
flexible thin film
metal hub
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sector18 per track
track80 per
side
Magnetic DisksMagnetic DisksMagnetic DisksMagnetic Disks
80 tracks per side X 18 sectors per track X 2 sides per disk X 512 bytes per sector = 1,474,560 bytes
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Optical DiscsOptical DiscsOptical DiscsOptical Discs
What are optical discs?� Flat, round, portable
metal discs made of metal, plastic, and lacquer
� Can be read only or Insert the disc,
Push the button toslide out the tray.
Push the same buttonto close the tray.
� Most PCs include an optical disc drive
� Can be read only or read/write
Insert the disc,label side up.
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Optical DiscsOptical DiscsOptical DiscsOptical Discs
How does a laser read data on an optical disc?
disc label
laserdiode
laserdiode
prism prism
light-sensingdiode
light-sensingdiode
0 1
lens lenspit land
Step 1.Laser diode shines a light beam towarddisc.
Step 2.If light strikesa pit, it scatters. If light strikes a land, it is reflected back toward diode.
Step 3.Reflected light is deflected to alight-sensing diode, which sends digital signals of 1 to computer. Absence of reflected light is read as digital signal of 0.
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Optical DiscsOptical DiscsOptical DiscsOptical Discs
How is data stored on an optical disc?� Typically stored in
single track� Track divided
into evenly sizedsectorssizedsectorsthat store items
single trackspirals to edgeof disc
disc sectors
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Optical DiscsOptical DiscsOptical DiscsOptical Discs
How should you care for an optical disc?
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Optical DiscsOptical DiscsOptical DiscsOptical Discs
What is a CD-ROM?� Compactdisc read-only memory� Single-session disc� Cannot erase or modify contents� Typically holds 650 MB to 1 GB� Commonly used to distribute multimedia and complex software
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Optical DiscsOptical DiscsOptical DiscsOptical Discs
What is the data transfer rate of a CD-ROM drive?
75XRanges from 48X to 75X
or fasteror faster
75 75 ×××××××× 150 KBps = 11,250 KBps 150 KBps = 11,250 KBps or 11.25 MBpsor 11.25 MBpsX is 150 KBps X is 150 KBps
(KB per second)(KB per second)
48X: 48X: 48 48 ×××××××× 150 KBps = 7,200 KBps 150 KBps = 7,200 KBps
or 7.2 MBpsor 7.2 MBps
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Optical DiscsOptical DiscsOptical DiscsOptical Discs
What is a Picture CD?
Film developers offer
Picture CD service
Can be modified
using photo editing software
Stores digital versions of roll of film service editing software
Step 3.At home, print images from Picture CD on your ink-jet photo printer.
At a store, print images to Picture CD at kiosk.
Step 1.Drop off film to be developed. Mark the Picture CD box on the film-processing envelope.
Step 2.When you pick up prints and negatives, a Picture CD contains digital images of each photograph.
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Optical DiscsOptical DiscsOptical DiscsOptical Discs
What are CD-Rs and CD-RWs? Must haveCD recorder
or CD-R drive
Cannot erasedisc’s contents
CD-R (compact disc-recordable)— multisession optical disc— can write on once, but not erase
CD-RW (compact disc-rewritable)—ceerasable multisession disc— can write on multiple times
Must haveCD-RW softwareand CD-RW drive
Disc reliabilitydrop with each successive rewriteSpeed: 52/24/52 [write – 52X or more, rewrite –24X or more, read – 52X or more ]
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CDCDCDCD----R and CDR and CDR and CDR and CD----RW drivesRW drivesRW drivesRW drives
CD-R drive
(speed: 40/48)
writes
CD-RW drive
(speed: 52/24/52)
+ CD-RW software
writes
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CDCDCDCD----R and CDR and CDR and CDR and CD----RW drivesRW drivesRW drivesRW drives
CD-R drive
(speed: 40/48)
reads
CD-RW drive
(speed: 52/24/52)
reads
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Video CDVideo CDVideo CDVideo CD
� Store video on a CD-R
� Can be played in CD or DVD drives, DVD players & some game consoles
� Hold 74 – 80 minutes of Hold 74 – 80 minutes of video
copy Digital media
RIPPING
PROCESS
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Optical DiscsOptical DiscsOptical DiscsOptical Discs
What is aDVD-ROM (digital versatile disc-ROM or digital video disc-ROM)?� Must haveDVD-ROM drive or
DVD player to read DVD-ROM� Stores databases, music,
complex software, and moviescomplex software, and movies� Blu-ray discshave storage
capacity of up to 100 GB� HD-DVD discshave storage
capacity of up to 60 GB� UMD can store up to 1.8 GB
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Optical DiscsOptical DiscsOptical DiscsOptical Discs
How does a DVD-ROM store data?1. Dense disc – closer pits2. Two layers of pits are used, lower layer is
semitransparent so laser can read through3. Some are double-sided
Many types of recordable and rewritable DVDs are available� DVD-R and DVD+R� DVD-RW and DVD+RW
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TapeTapeTapeTape
What is tape?� Magnetically coated plastic ribbon
capable of storing large amountsof data at low cost
� Primarily used for backup� Low cost� Long term storage
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TapeTapeTapeTape
How is data stored on a tape?� Sequential access
� Unlike Direct access/Random access— used on hard disks, CDs, and DVDs — which can
� Reads and writes data consecutively, like music tape
on hard disks, CDs, and DVDs — which can locate particular item immediately
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PC Cards and ExpressCard ModulesPC Cards and ExpressCard ModulesPC Cards and ExpressCard ModulesPC Cards and ExpressCard Modules
What are PC Cards and ExpressCard Modules?� Adds capabilities to computer
� Credit-card-sized device commonly used in notebook computers
� Add memory, storage, communications, multimedia, and security capabilities to a computermultimedia, and security capabilities to a computer
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Miniature Mobile Storage MediaMiniature Mobile Storage MediaMiniature Mobile Storage MediaMiniature Mobile Storage Media
What is miniature mobile storage media?� Storage for small mobile devices
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Miniature Mobile Storage MediaMiniature Mobile Storage MediaMiniature Mobile Storage MediaMiniature Mobile Storage Media
What are common types of flash memory cards?
CompactFlash Secure Digital xD Picture Card
Memory Stick Memory Stick PRO Duo
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Miniature Mobile Storage MediaMiniature Mobile Storage MediaMiniature Mobile Storage MediaMiniature Mobile Storage Media
How does one type of flash memory card work?
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Miniature Mobile Storage MediaMiniature Mobile Storage MediaMiniature Mobile Storage MediaMiniature Mobile Storage Media
What is a USB Flash Drive?� Plugs in a USB port on a
computer or mobile device� Storage capacities up to 64 GB� May eventually make the
floppy disk obsolete� Also called U3 Smart device� Also called U3 Smart device� Transfer rate: 12 MBps
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Miniature Mobile Storage MediaMiniature Mobile Storage MediaMiniature Mobile Storage MediaMiniature Mobile Storage Media
What is a smart card?� Stores data on microprocessor embedded in small card� Input, process, output, and storage capabilities� Used to store medical records, vaccination data, and other
health-case and identification information; tracking information – employee attendance or customer purchase, authenticating users for building accessusers for building access
Are credit cards smart cards?
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Microfilm and MicroficheMicrofilm and MicroficheMicrofilm and MicroficheMicrofilm and Microfiche
What are microfilm and microfiche?
Images recorded using Images recorded using computer output microfilm recordercomputer output microfilm recorder
Store microscopic images of Store microscopic images of documents on roll or sheet of filmdocuments on roll or sheet of film
computer output microfilm recordercomputer output microfilm recorder
Microfilm — 100- to215-foot roll of film
Microfiche — small sheet of film, usually 4” ×××× 6”
� Used to store back issues of newspapers, magazines, inactive files, transactions and cancelled checks,…
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Microfilm and MicroficheMicrofilm and MicroficheMicrofilm and MicroficheMicrofilm and Microfiche
How do life expectancies of various media compare?� Microfilm and microfiche are inexpensive % have longest life of
any storage media
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Putting It All TogetherPutting It All TogetherPutting It All TogetherPutting It All Together
What are recommended storage devices for home users?
� 250 GB hard disk� Online storage� CD or DVD drive� Card reader/writer� Card reader/writer� USB flash drive
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Putting It All TogetherPutting It All TogetherPutting It All TogetherPutting It All Together
What are recommended storage devices for small office/home office (SOHO) users?
� 500 GB hard disk� Online storage� CD or DVD drive� External hard drive for backup� External hard drive for backup� USB flash drive
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Putting It All TogetherPutting It All TogetherPutting It All TogetherPutting It All Together
What are recommended storage devices for mobile users?
� 100 GB hard disk� Online storage� CD or DVD drive� Card reader/writer� Card reader/writer� Portable hard disk for backup� USB flash drive
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Putting It All TogetherPutting It All TogetherPutting It All TogetherPutting It All Together
What are recommended storage devices for power users?
� 1.5 TB hard disk� Online storage� CD or DVD drive� Portable hard disk for backup� Portable hard disk for backup� USB flash drive
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Putting It All TogetherPutting It All TogetherPutting It All TogetherPutting It All Together
What are recommended storage devices for large business users?
� Desktop computer�500 GB hard disk�CD or DVD drive�Smart card reader�Smart card reader�Tape drive�USB flash drive
� Server or Mainframe�Network storage server�40 TB hard disk system�CD-ROM or DVD-ROM server�Microfilm or microfiche
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Summary of StorageSummary of StorageSummary of StorageSummary of Storage
Internal hard disksInternal hard disks
External and removable hard disksExternal and removable hard disks
Floppy disksFloppy disks
HD DVD discsHD DVD discs
Recordable and Rewritable DVDsRecordable and Rewritable DVDs
TapeTapeCD-ROMsCD-ROMs
Recordable and Rewritable CDsRecordable and Rewritable CDs
DVD-ROMsDVD-ROMs
Blu-ray Discs (BDs)Blu-ray Discs (BDs)
TapeTape
PC Cards and ExpressCard modules
PC Cards and ExpressCard modules
Flash memory cards and USB flash drives
Flash memory cards and USB flash drives
Chapter 5 Complete
Smart cards, microfilm, and microfiche
Smart cards, microfilm, and microfiche