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Chapter
Storage
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Chapter Objectives
Differentiate between storage devicesand storage media
Describe the characteristics ofmagnetic disks
Describe the characteristics ofa hard disk
Differentiate between floppy disksand Zip disks
Describe the characteristicsof optical discs
Differentiate among CD-ROMs,recordable CDs, rewritable CDs,
DVD-ROMs, recordable DVDs, andrewritable DVDs
Identify the uses of tape
Discuss PC Cards and the various typesof miniature mobile storage media
Identify uses of microfilm andmicrofiche
Next
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Storage
What isstorage?
p. 354 Fig. 7-1 Next
Holds data, instructions, and information for future use
Storage mediumis physical material used for storage
Also called secondary storage
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Storage
What iscapacity?
p. 356 Next
Kilobyte (KB) 1 thousand
Megabyte (MB) 1 million
Gigabyte (GB) 1 billion
Terabyte (TB) 1 trillion
Petabyte (PB) 1 quadrillion
Number of bytes (characters) a storage medium can hold
Exabyte (EB) 1 quintillion
Zettabyte (ZB) 1 sextillion
Yottabyte (YB) 1 septillion
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Storage Medium
(floppy disks, Zip disks,
hard disks, CDs)
Storage
How does volatility compare?
p. 356 Next
Nonvolatile
Storage medium is nonvolatilecontents retained whenpower is off
Contents
retained
Contents
available to user
Memory
(most RAM)
(chips on motherboard)
Screen Display
ON OFF
Volatile Display
disappears
Data and
instructions
available to user
Display
appears
Data and
instructions erased
Memory is volatileholds data and instructions temporarily
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Writing
Process of transferring
items from memory
to storage media
Storage
What is astorage device?
p. 356 Next
Reading
Process of transferring
items from storage
media to memory
Hardware that
records and
retrieves items
to and from
storage media
Functions as source
of inputCreates output
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Floppy Disk Small files to be transported
Secondary Storage
Primary Storage
Hard Disk
Flash Memory Cardsand USB Flash Drives
CDs and DVDs
Tape
Items waiting to be interpretedand executed by the processor
Operating system, application
software, user data and information
Digital pictures or filesto be transported
Software, backups, movies, music
Backups
Memory (most RAM)
Stores Transfer rates
Storage
What isaccess time?
p. 357 Fig. 7-4
Time it takes storage device to locate item on storage medium
Next
Time required to deliver item from memory to processor
fastertransfer
rates
slowertransfer
rates
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Magnetic Disks
p. 357 Fig. 7-5 Next
What aretracks andsectors?
Formattingprepares disk for use and marks bad sectors as unusable
Track
is narrow
recording band
that forms fullcircle on disk
Sector
stores up to
512 bytesof data
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Perpendicular recording
Magnetic Disks
What is ahard disk?
p. 358 Fig. 7-6 Next
hard disk installedin system unit
High-capacity storage
Consists of severalinflexible, circularplatters that store items
electronically
Components enclosed inairtight, sealed case forprotection
Click to view Web Link,click Chapter 7, Click Web Linkfrom left navigation,then click PerpendicularRecording below Chapter 7
Longitudinal recording
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Magnetic Disks
What are characteristics of a hard disk?
p. 359 Fig. 7-7 Next
Sample Hard Disk Characteristics
Advertised capacity 120 GB
Platters 3
Read/write heads 6Cylinders 16,383
Bytes per second 512
Sectors per track 63
Sectors per drive 234,441,648
Revolutions per minute 7,200
Transfer rate 133 MB per second
Access time 8.9 ms
actualdisk
capacity
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Magnetic Disks
How does a hard disk work?
p. 360 Fig. 7-8 Next
Step 1.Circuit board controls
movement of head actuator
and a small motor.
Step 2.Small motor spins
platters while
computer is running.
Step 3.When software requests a
disk access, read/write
heads determine current
or new location of data.
Step 4.
Head actuator positionsread/write head arms over
correct location on platters
to read or write data.
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Video: Install a New Hard Drive
Speed up your computer with a new hard drive
low quality
(click to start)
high quality(click to start)
Next
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Magnetic Disks
What is acylinder?
p. 360 Fig. 7-9 Next
Vertical section of
track through all
platters
Single movement
of read/write head
arms accesses all
platters
in cylinder
platter
read/writehead
platter
sides
cylinder
track
sector
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Magnetic Disks
What is ahead crash?
p. 360-361 Fig. 7-10 Next
clearance
read/write head
platter
hair
dust
smoke
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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hard disk
Next
Magnetic Disks
What is adisk cache?
p. 361 Fig. 7-11
Portion of
memory that
processor uses
to store
frequently
accessed items
second requestfor datato hard disk
disk cache
first requestfor datato disk cache
processor
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Next
Magnetic Disks
What is aminiature hard disk?
p. 362 Fig. 7-12
Provide users with greater storage capacities than
flash memory
Some have a form factor of less than 1 inch
Storage capacities range from 2 GB to 100 GB
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Magnetic Disks
What areexternal hard disksandremovable hard disks?
p. 362 Fig. 7-12 Next
External hard diskfreestanding
hard disk that connects to system unit
Removable hard diskhard disk
that you insert and remove
from hard disk drive
Used to back up or transfer files
Click to view WebLink, click Chapter 7, ClickWeb Link from leftnavigation, then clickMiniature Hard Disks orRemovable Hard Disksbelow Chapter 7
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SCSI
(Small ComputerSystem Interface)controller supports up to fifteendevices including hard disks, CD
and DVD drives, tape drives, printers,scanners, network cards
SATA(Serial Advanced
Technology Attachment) controller
uses serial signals to transfer data,
instructions, and information
Magnetic Disks
What is adisk controller?
p. 363 Next
EIDE(EnhancedIntegrated Drive
Electronics) controller supports four
hard disks, provides connections for
CD and DVD drives
Chip and circuits that
control transfer ofitems from disk
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Magnetic Disks
What is online storage?
p. 363 Fig. 7-14 Next
Others can be authorized
to access your data
Service on Web that provides storage for
minimal monthly fee
Files can be accessed from
any computer with Web
access Large files can be downloaded
instantaneously
Click to view WebLink, click Chapter 7, ClickWeb Link from leftnavigation, then clickOnline Storagebelow Chapter 7
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Magnetic Disks
What is afloppy disk?
p. 364 Next
Portable, inexpensive storage
medium (also called diskette)
Thin, circular, flexible film enclosed
in 3.5 wide plastic shell
shutter
shell
liner
magneticcoating
flexible thin film
metal hub
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Magnetic Disks
What is afloppy disk drive?
p. 364 Fig. 7-15 Next
Floppy disk drive built intoa desktop computer
External floppy disk drive
attaches to a computer with
a cable Also called secondary storage
One floppy drive, named drive A
Device that reads from and
writes to floppy disk
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Magnetic Disks
What is awrite-protect notch?
p. 365 Next
Small opening with a cover that you slide
Protects floppy disk from being erased accidentally
hole on thisside meansdisk is high
density
write-protected
not write-protected
notch closedmeans you
can write onthe disk
notch open
means youcannot writeon the disk
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Magnetic Disks
How do you compute a disks storage capacity?
p. 359 Next
Multiply number of sides, number of tracks, number of sectors per
track, and number of bytes per sector
For high-density disk: 2 sides 80 tracks 18 sectors per track 512
bytes per sector = 1,474,560 bytes
Characteristics of a
3.5-inch High-Density
Floppy Disk
Capacity: 1.44 MB
Sides: 2
Tracks: 80
Sectors per track: 18
Bytes per sector: 512
Sectors per disk: 2880
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Magnetic Disks
What is aZip disk?
p. 365 Fig. 7-16 Next
Magnetic medium that stores 100 MB
to 750 MB of data
Zip disks require aZip drivecchigh
capacity drive that reads from and
writes on a Zip disk
Used to back up and to transfer files Backupis duplicate of file, program, or disk
in case original is lost c
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Push the same buttonto close the tray.
Optical Discs
What areoptical discs?
p. 366 Fig. 7-17 Next
Most PCs include an
optical disc drive
Flat, round, portable
metal discs made of
metal, plastic, and
lacquer
Can be read only or
read/write
Insert the disc,label side up.
Push the button to
slide out the tray.
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Optical Discs
How does a laser read data on an optical disc?
p. 367 Fig. 7-18 Next
laser
diode
laser
diode
prism prism
light-sensingdiode
light-sensingdiode
0 1
lens lenspit land
disc label
Step 1.Laser diode
shines a light
beam toward
disc.
Step 2.If light strikes
a pit, it scatters.
If light strikes a
land, it is
reflected back
toward diode.
Step 3.Reflected light is
deflected to a
light-sensing diode,
which sends digital
signals of 1 tocomputer. Absence
of reflected light is
read as digital
signal of 0.
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Optical Discs
How is data stored on an optical disc?
p. 367 Fig. 7-19 Next
Typically stored in
singletrack
Track divided
into evenly
sizedsectorsthat store
items
single track
spirals to edge
of disc
disc sectors
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Optical Discs
How should you care for an optical disc?
p. 230 Fig. 7-20 Next
Do store thedisc in a jewelbox whennot in use
Do hold a discby its edges
Do noteat, smoke, ordrink neara disc
Do not stack discs
Do not exposethe disc toexcessiveheat orsunlight
Do not touchthe undersideof the disc
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Optical Discs
What is aCD-ROM?
p. 369 Fig. 7-22 Next
Compactdiscread-onlymemory 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 Discs
What is the data transfer rate of a CD-ROM drive?
p. 369 Next
75XRanges from
48X to 75X
or faster
75 150 KBps = 11,250 KBps
or 12.25 MBps75X is 150 KBps
(KB per second)
48X:
48 150 KBps = 7,200 KBps
or 7.2 MBps
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Optical Discs
What is aPicture CD?
p. 370 Fig. 7-23 Next
Film developersoffer
Picture CD
service
Can bemodified
using photo
editing software
Stores digitalversions of
roll of film
Step 3.At home, print images
from Picture CD onyour ink-jet photo printer.
At a store, print images to
Picture CD at kiosk.
Step 1.Drop off film to
be developed.
Mark the PictureCD box on the
film-processing
envelope.
Step 2.When you pick up
prints and negatives, a
Picture CD contains
digital images of each
photograph.
Click to view Web Link,click Chapter 7, Click Web Linkfrom left navigation,then click Picture CDs belowChapter 7
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Optical Discs
What areCD-Rsand CD-RWs?
p. 371 Next
Must have
CD recorderor CD-R drive
Cannot erase
discs contents
CD-R(compact disc-recordable)
cdisc you can write on once
CD-RW(compact disc-rewritable)
ceerasable disc you can write on
multiple times
Must haveCD-RW software
andCD-RW driveClick to view WebLink, click Chapter 7, ClickWeb Link from leftnavigation, then clickCD-Rs and CD-RWsbelow Chapter 7
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Optical Discs
What is aDVD-ROM(digital versatile
disc-ROM or digital video disc-ROM)?
p. 372 Fig. 7-24 Next
Must haveDVD-ROM driveor
DVD player to read DVD-ROM
Stores databases, music,
complex software, and movies Blu-ray discshave storage
capacity of up to 27 GB
HD-DVD discshave storage
capacity of up to 45 GB UMDcan store up to 1.8 GB
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Optical Discs
How does a DVD-ROM store data?
p. 372 Fig. 7-25 Next
Two layers of pits are used, lower layer issemitransparent so laser can read through
Some are double-sided
Many types of recordable and rewritable DVDs are
available DVD-R and DVD+R
DVD-RWand DVD+RW
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Tape
What istape?
p. 374 Fig. 7-27 Next
Magnetically coated plastic ribbon
capable of storing large amounts
of data at low cost
Primarily used for backup
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Tape
How is data stored on a tape?
p. 374 Next
Sequential access
Unlike direct accessused on floppy disks, Zip disks,
hard disks, CDs, and DVDswhich can locate
particular item immediately
Reads and writes data consecutively, like music tape
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PC Cards
What is aPC Card?
p. 374 Figs. 7-28
7-29 Next
Adds capabilities to computer Credit-card-sized device commonly
used in notebook computers
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Miniature Mobile Storage Media
What isminiature mobile storage media?
p. 375 Fig. 7-30 Next
Storage for small mobile devices
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Miniature Mobile Storage Media
What are common types of flash memory cards?
p. 376 Fig. 7-31 Next
Click to view WebLink, click Chapter 7, ClickWeb Link from leftnavigation, then clickFlash Memory Cards belowChapter 7
CompactFlash Smart Media Secure Digital
Memory Stick xD Picture Card
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Miniature Mobile Storage Media
p. 377 Fig. 7-32 Next
How does one type of flash memory card work?
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Miniature Mobile Storage Media
What is aUSB Flash Drive?
p. 377 Fig. 7-33 Next
Plugs in a USB port on a
computer or mobile device
Storage capacities up to 4 GB
May eventually make the
floppy disk obsolete
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Miniature Mobile Storage Media
What is asmart card?
p. 378 Fig. 7-34 Next
Stores data on microprocessor
embedded in small card
Input, process, output, and
storage capabilities
Click to view WebLink, click Chapter 7, ClickWeb Link from leftnavigation, then clickSmart Cardsbelow Chapter 7
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Microfilm and Microfiche
What aremicrofilmandmicrofiche?
p. 379 Fig. 7-35 Next
Images recorded using
computer output microfilm
recorder
Store microscopic images of
documents on roll or sheet of
film
Microfilm100- to
215-foot roll of film
Microfichesmall sheet
of film, usually 4 6
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Microfilm and Microfiche
How do life expectancies of various media compare?
p. 379 Fig. 7-36 Next
Microfilm and microfiche have longest life of any storage media
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Putting It All Together
What are recommended storage devices for home
users?
p. 380 Fig. 7-38 Next
160 GB hard disk
Online storage
CD or DVD drive
Card reader/writer
USB flash drive
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Putting It All Together
What are recommended storage devices for small
office/home office (SOHO) users?
p. 380 Fig. 7-38 Next
250 GB hard disk
Online storage
CD or DVD drive
External hard drive for backup
USB flash drive
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Putting It All Together
What are recommended storage devices for mobile
users?
p. 380 Fig. 7-38 Next
100 GB hard disk
Online storage
CD or DVD drive
Card reader/writer
Portable hard disk for backup
USB flash drive, and/or 5 GB PC Card hard
disk
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Putting It All Together
What are recommended storage devices for power
users?
p. 380 Fig. 7-38 Next
CD or DVD drive
500 GB hard disk
Online storage
Portable hard disk for backup
USB flash drive
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Putting It All Together
What are recommended storage devices for large
business users?
p. 380 Fig. 7-38 Next
Desktop computer
250 GB hard disk
CD or DVD drive
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 Storage
Internal hard disks
Portable hard disks
Floppy disks
Zip disks
CD-ROMs
Recordable and Rewritable CDs
DVD-ROMs
Recordable DVDs
Rewritable DVDs
Tape
PC Cards
Flash memory cards and
USB flash drives
Smart cards, microfilm, andmicrofiche