chapter 7 storage te-102 introduction to computing
TRANSCRIPT
Chapter 7 Objectives
Discuss the various types of items that users store on computer media
Discuss the various types of items that users store on computer media
Differentiate between storage devicesand storage media
Differentiate between storage devicesand storage media
Describe the characteristics ofa floppy disk drive
Describe the characteristics ofa floppy disk drive
Identify the uses of Zip disksIdentify the uses of Zip disks
Describe the characteristics ofa hard disk
Describe the characteristics ofa hard disk
Identify the advantages of usingan Internet hard drive
Identify the advantages of usingan Internet hard drive
Describe the characteristics ofCDs and DVDs
Describe the characteristics ofCDs and DVDs
Differentiate among CD-ROMs,CD-RWs, DVD-ROMs, and DVD+RWs
Differentiate among CD-ROMs,CD-RWs, DVD-ROMs, and DVD+RWs
Identify the uses of tapeIdentify the uses of tape
Discuss PC Cards and the various typesof miniature storage media
Discuss PC Cards and the various typesof miniature storage media
Identify uses of microfilm and microfiche
Identify uses of microfilm and microfiche
Next
Storage
What is storage?
p. 7.02 Fig. 7-1 Next
Holds data, instructions, and information for future use Storage medium is physical material used for storage
Also called secondary storage
Floppy disk
microfiche
Miniatgure mobile storage media
Zip disk
PC card
Internal hard disk
External hard disk
Removable hard disk
tape
CD or DVD
Storage
What is capacity?
p. 7.04 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
Storage Medium(floppy disks, Zip disks,
hard disks, CDs)
Storage
How does volatility compare?
p. 7.04 Next
No
nvo
lati
le
Storage medium is nonvolatile—contents retained when power is off
Contents Contents retainedretained
Contents Contents available to useravailable to user
Memory(most RAM)
(chips on motherboard)
Screen Display
ON OFF
Vo
lati
le Display Display disappearsdisappears
Data andData andinstructions instructions
available to useravailable to user
Display Display appearsappears
Data and Data and instructions erasedinstructions erased
Memory is volatile—holds data and instructions temporarily
WritingWritingProcess of transferring Process of transferring
items from memory items from memory to storage mediato storage media
WritingWritingProcess of transferring Process of transferring
items from memory items from memory to storage mediato storage media
Storage
What is a storage device?
p. 7.04 Next
ReadingReadingProcess of transferring Process of transferring
items from storage items from storage media to memorymedia to memory
ReadingReadingProcess of transferring Process of transferring
items from storage items from storage media to memorymedia to memory
Hardware that Hardware that records and records and
retrieves items retrieves items to and from to and from
storage mediastorage media
Functions as source of input
Creates output
Floppy Disk Small files to be transported
Secondary Storage
Primary Storage
Hard Disk
CDs and DVDs
Miniature Storage Media
Tape
Items waiting to be interpretedand executed by the processor
Operating system, applicationsoftware, user data and information
Software, backups, movies, music
Digital pictures or small files tobe transported
Backups
Memory (most RAM)
Stores …
Storage
What is access time?
p. 7.04
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
Floppy Disks
What is a floppy disk?
p. 7.05 Fig. 7-5 Next
Portable, inexpensive storage medium (also called diskette)
Thin, circular, flexible film enclosedin 3.5” wide plastic shell
shutter
shell
liner
magneticcoating
flexible thin film
metal hub
Floppy Disks
What is a floppy disk drive?
p. 7.06 Fig. 7-6 Next
Floppy disk drive built intoa desktop computer
External floppy disk drive attaches toa computer with a cable
Also called secondary storage
One floppy drive, named drive A If two floppy drives, second
designated as drive B
Device that reads from andwrites to floppy disk
Floppy Disks
How does a floppy disk drive work?
p. 7.06 Fig. 7-7 Next
Step 1. When you insert the floppy disk into drive, shutter moves to the side to expose the recording surface on disk.
Step 2. When you initiate a disk access, circuit board on drive that contains electronics sends signals to control movement of read/write heads until they barely touch surface (film) inside floppy disk’s shell.
Step 3. For write instructions, circuit board verifies whether or not disk can be written on.Step 4. Motor spins
a shaft, which causes surface inside floppy disk’s shell to spin.
Step 5. Motor positions read/write heads over correct location on recording surface of disk.
Step 6. Read/write heads read data from and write data on floppy disk.
Floppy Disks
p. 7.07 Fig. 7-8 Next
What are tracks and sectors?
Trackis narrow
recording bandthat forms fullcircle on disk
Sector stores up to512 bytes
of data
Formatting prepares disk for use and marks bad sectors as unusable
Click to view Web Link,then click Floppy Disksbelow Chapter 7
Floppy Disks
How do you compute a disk’s storage capacity?
p. 7.08 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 a3.5-inch High-DensityFloppy Disk
Capacity: 1.44 MB
Sides: 2
Tracks: 80
Sectors per track: 18
Bytes per sector: 512
Sectors per disk: 2880
Floppy Disks
p. 7.08 Next
Never open theshutter and
touch the disk’ssurface
Never open theshutter and
touch the disk’ssurface
How do you care for a floppy?
Avoid exposureto heat and
cold
Avoid exposureto heat and
coldAvoid exposure
to magneticfields
Avoid exposureto magnetic
fields Avoid exposureto contaminants
such as dust,smoke, or
salt air
Avoid exposureto contaminants
such as dust,smoke, or
salt airKeep disks ina storage tray
when notusing them
Keep disks ina storage tray
when notusing them
Proper care helps maximize disk’s life Floppy disk can last at least seven years
Floppy Disks
What is a write-protect notch?
p. 7.08 Fig. 7-10 Next
Small opening with a cover that you slide Protects floppy disk from being erased accidentally
hole on thisside meansdisk is high
density
hole on thisside meansdisk is high
density
write-protected
not write-protected
notch closedmeans you
can write onthe disk
notch closedmeans you
can write onthe disk
notch openmeans you
cannot writeon the disk
notch openmeans you
cannot writeon the disk
ExternalZip drive
Zip® Disks
What is a Zip disk?
p. 7.09 Fig. 7-11 Next
Magnetic medium that stores from 100 MB to 750 MB of data
Zip disks require a Zip drivec—chigh capacity drive that reads from and writes on a Zip disk Built-in Zip drive External Zip drive : connects to
a USB, FireWire or parallel port
Used to back up and to transfer files Backup is duplicate of file, program, or disk
in case original is lostc
Zip disk
Hard Disks
What is a hard disk?
p. 7.09 Fig. 7-12 Next
hard disk installedin system unit
High-capacity storage ( 40 to 250 GB and more)
Consists of several inflexible, circular platters that store items electronically
Components enclosed in airtight, sealed case for protection
Sometimes called a fixed disk because it is
mounted in a drive bay and usually is not potable
Hard Disks
What are characteristics of a hard disk?
p. 7.10 Fig. 7-13 Next
The capacity of a hard disk is determined from the number of platters it contains, together withcomposition of themagnetic coating on the platters.
Hard Disks
How does a hard disk work?
p. 7.11 Fig. 7-14 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 positions read/write head arms over correct location on platters to read or write data.
Hard Disks
What is a cylinder?
p. 7.11 Fig. 7-15 Next
Vertical section of track through all platters
Single movement of read/write head arms accesses all plattersin cylinder
platter
read/writehead
platter
sides
cylinder
track
sector
Hard Disks
What is a head crash?
p. 7.12 Fig. 7-16 Next
clearance
read/write head
platter
hair
dustsmoke
Spinning creates cushion of air that floats read/write head above platter
Head crash results in a loss of data or sometimes loss of the entire drive - Needs to backup the hard disk regularly.
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
Hard Disks
Hard disk access time can be improved by using disk caching.
Two types of cache : memory cache and disk cache. Memory cache: used to improve the memory access
time. L1 and L2 cache for most PC, L3 cache for server. L1 and L2 are built directly on to the processor chip. Search order: L1, then L2, then L3 (if it exists), then RAM
Disk cache: used to improve the hard disk access time
hard disk
Next
Hard Disks
What is a disk cache?
p. 7.12 Fig. 7-17
Portion of memory that processor uses to store frequently accessed items
second requestfor data—to hard disk
disk cache
first requestfor data—to disk cache
processor
Hard Disks
What are external hard disks and removable hard disks?
p. 7.13 Fig. 7-18 Next
External hard disk—freestandinghard disk that connects with a cable to a USB, FireWire or other port on the system unit. Storage capacities up to 250 GB or higher
Used to back up or transfer files
Removable hard disk—hard diskthat you insert and removefrom hard disk driveStorage capacities up to 80 GB or higher
Hard Disks
What is a disk controller?
p. 7.13 Next
EIDEEIDE (EEnhancednhanced IIntegratedntegrated DDrive 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
Chip and circuits that Chip and circuits that control transfer of control transfer of items from diskitems from disk
SCSISCSI((SSmallmall CComputeromputer SSystemystem IInterface)nterface)
controller 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
Hard Disks
What is an Internet hard drive (online storage)?
p. 7.14 Fig. 7-19 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 Web Link,then click Hard Drivesbelow Chapter 7
Push the same buttonto close the tray.
CDs and DVDs
What are CDs and DVDs?
p. 7.15 Fig. 7-20 Next
Most PCs include CD or DVD drive, most play audio CDs
Flat, round, portable metal discs with protective plastic coating
These are optical media that store items by using microscopic pits and lands
Insert the disc,label side up.
Push the button toslide out the tray.
CDs and DVDs
How does a laser read data on a CD or DVD?
p. 7.16 Fig. 7-21 Next
laserdiode
laserdiode
prism prism
light-sensingdiode
light-sensingdiode
0 1
lens lenspit land
disc label
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.
CDs and DVDs
How is data stored on a CD or DVD?
p. 7.16 Fig. 7-22 Next
Typically stored in single track
Track divided into evenly sized sectors that store items
single trackspirals to edgeof disc
disc sectors
CDs and DVDs
How should you care for a CD or DVD?
p. 7.16 Fig. 7-23 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 to excessiveheat or sunlight
Do not touchthe undersideof the disc
CDs and DVDs
What is a CD-ROM?
p. 7.17 Fig. 7-24 Next
Compact disc read-only memory A type of optical disc that uses laser technology to store data.
Cannot erase or modify contents. Called a single-session disc because manufactures write all items on the disc at one time. Typically holds 650 MB to 1 GB. Commonly used to distribute
multimedia and complex software (Encyclopedias, games…)
CDs and DVDs
The speed of a CD-ROM drive determines how fast the
drive installs program and accesses the disc. Original CD-ROM drives: single speed drives with
transfer rates of 150 KBps (Kilobytes per second). To measure the transfer rate, manufacturers use the
relative values of the transfer rate of this original CD-
ROM drives They use an X to denote the original transfer rate of 150
KBps.
What is the data transfer rate of a CD-ROM drive?
CDs and DVDs
What is the data transfer rate of a CD-ROM drive?
p. 7.18 Next
75X
Ranges from 48X to 75X
or faster
75 75 150 KBps = 11,250 KBps 150 KBps = 11,250 KBps 48X: 48X:
48 48 150 KBps = 7,200 KBps 150 KBps = 7,200 KBps
CDs and DVDs
What is a Picture CD?
p. 7.19 Fig. 7-25 Next
Film developers offer
Picture CD service
Can be modified
using photo editing software
A type of CD that stores digital versions of
roll of film using a jpg file format
Step 3.At home, print images from Picture CD with your ink-jet photo printer.
At a store, print images from 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.
CDs and DVDs
What is a PhotoCD?
Another type of CD that stores digital photographic images. A single PhotoCD stores images from multiple rolls of
film using the Image Pac, or PCD, file format developed
by Kodak. Designed for commercial and professional users. Available in many resolutions, ranging from 128 x 192
to 4096 x 6411 pixels. A PhotoCD is a multisession disc; users can save
additional photos on the disc at a later time.
CDs and DVDs
What is a CD-R (compact disc-recordable)?
Multi-session CD with which users write on part of the disc at one time and another part at a later time. Disc’s contents cannot be erased. Most current CD-ROM drives can read a CD-R. CD-R drives can read both audio CDs and standard CD-ROMs. Speed of CD-R drive
Reading speed: 48X or more Writing speed: 40X or more Manufactures list the writing speed first and reading speed next, such as 40/48.
Slightly more expensive than standard CD-ROM drives.
CDs and DVDs
What is a CD-RW (compact disc-rewritable)? Erasable disc users can write on multiple times. CD-RW overcomes the major disadvantage of CD-R disc. With CD-RW, the disc acts like a floppy disk or hard disk, allowing users to write and rewrite data onto it multiple times. Reliability of disc tends to drop with each successive rewrite. Speed of CD-RW drive
writing speed: 52X or more rewriting speed: 24X or more reading speed: 52X or more Manufacturers state the speeds in the above order: 52/24/52.
Multithread CD drive is a drive that reads audio CDs, data CDs, CD-Rs, and CD-RWs. Most current CD drives are multithread.
CDs and DVDs
Comparison of CD-ROM, CD-R and CD-RW
p. 7.20
Must haveCD recorder
or CD-R drive
CD-R (compact disc-recordable)— multi-session CD
CD-RW (compact disc-rewritable)—ceerasable disc you can write on
multiple times Must haveCD-RW softwareand CD-RW drive
CD-ROM (compact disc read only memory)— single-session CD Must have
CD-ROM drive
How is an audio CD created?
Step 5.User listensto song ona personal computer or removes CD and listens to song ona portable CD player.
Step 2.Song is stored on audio CD andpurchasedby user.
Step 1.Artist composes a song.
Step 3.User inserts audio CD into CD drive, plays song, and rips desired tracks onto hard disk.
Step 4.User copies file to aCD-RW disc.
Nextp. 7.20 Fig. 7-26
CDs and DVDs
From a purchased CD. . .
CDs and DVDs
Step 3.User pays for and downloads song as audio file onto a hard disk.
Step 2.Song is compressed and stored on the Internet.
How is an audio CD created? From the Internet. . .
p. 7.20 Fig. 7-26 Next
Step 5.User listensto song ona personal computer or removes CD and listens to song ona portable CD player.
Step 1.Artist composes a song.
Step 4.User copies file to aCD-RW disc.
CDs and DVDs
What is a DVD-ROM (digital versatile disc-ROM or digital video disc-ROM)?
p. 7.22 Fig. 7-27 Next
DVD
DVD drive
High capacity disc capable of storing 4.7 GB to 17 GB
Must have DVD-ROM drive or DVD player to read DVD-ROM
Newer DVD-ROM drive, CD-RW/DVD, can read audio CDs, CD-ROMs, CD-Rs, and CD-RWs
Stores databases, music, complex software, and movies
CDs and DVDs
How does a DVD-ROM store data?
DVD-ROM uses one of three storage techniques Make the disc denser by packing the pits closer
together. Two layers of pits are used, lower layer is
semitransparent so laser can read through Some are double-sided
DVD-ROM Storage Capacities
Sides Layers Storage Capacity
1 1 47 GB
1 1 8.5 GB
2 1 9.4 GB
2 2 17 GB
CDs and DVDs
DVD Variations
DVD-R (DVD-recordable) DVD+RW (DVD-rewritable) DVD+RAM (DVD+random access memory) : allow users to erase and record on a DVD+RAM discs more than 100,000 times. Storage capacity up to 4.7 GB per side
Tape
What is tape?
p. 7.24 Fig. 7-29 Next
Magnetically coated plastic ribboncapable of storing large amountsof data at low cost
Primarily used for backup Tape drive reads and writes data on a tape
Tape drive
Tape cartridge
Tape
How is data stored on a tape? Sequential access
Digital audio tape DAT 2 GB to 240 GB
(also called digital data storage) (also called DDS)
Digital linear tape DLT 20 GB to 229 GB
Linear tape-open LTO 100 GB to 200 GB
Quarter-inch cartridge QIC 40 MB to 25 GB
Travan TR 8 GB to 40 GB
Popular Types of Tape
Name Abbreviation Storage Capacity
Unlike direct access (random access) — used on floppy disks, Zip disks, hard disks, CDs, and DVDs — which can locate particular item immediately
Reads and writes data consecutively, like music tape
PC Cards
What is a PC Card?
p. 7.24 Figs. 7-31–7-32 Next
PC Cards
Category Thickness Use
Type I 3.3 mm RAM, SRAM, flash
memory
Type II 5.0 mm Modem, LAN, SCSI,
sound, TV turner, hard
disk, or other storage
Type III 10.5 mm Rotating storage such
as a hard disk
Adds capabilities to computer Credit-card-sized device commonly
used in notebook computers
Miniature Mobile Storage Media
What is miniature mobile storage media?
p. 7.25 Fig. 7-33 Next
Storage for small mobile devices
Miniaturemobile storage
media
Miniature Mobile Storage Media
What are common types of miniature mobile storage media? (Refer to the Figure 7-34 for storage capacity and use)
Next
Smart Media Secure Digital
Microdrive ™ USBDrive™Memory Stick ®
CompactFlash
Miniature Mobile Storage Media
p. 7.27 Fig. 7-35 Next
What is a card reader? Reads information stored on miniature mobile storage media Type of card determines type of card reader needed
Miniature Mobile Storage Media
What is a USB flash drive (keychain drive)?
Flash memory storage device that plugs into a USB port on a computer or potable device Storage capacity is up to 32 GB Data transfer rate is about 16 MBps
Miniature Mobile Storage Media
What is a smart card?
p. 7.27 Fig. 7-36 Next
Stores data on microprocessor embedded in small card
Difference with a flash memory card: Flash memory card has only
storage capabilities. Smart card contains a
processor and have input, process, output, and storage capabilities
Sometimes called intelligent smart card
Miniature Mobile Storage Media
Where is a smart card used?
To store a prepaid dollar amount, as in a prepaid telephone calling card or electronic money To store medical records, vaccination data, and other health- care information To track information such as customer purchases or employee attendance
Miniature Mobile Storage Media
What is e-money (electronic money)?
p. 7.28 Next
Sometimes placed Sometimes placed on smart cardon smart card
Means of paying forMeans of paying forgoods and servicesgoods and services
over the Internetover the InternetAlso called digital cashAlso called digital cash
Bank issues unique Bank issues unique digital cash numbers digital cash numbers that represent amount that represent amount of moneyof money
Money is withdrawn Money is withdrawn from your bank from your bank accountaccount
Microfilm and Microfiche
What are microfilm and microfiche?
p. 7.28 Fig. 7-37 Next
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
Microfilm — 100- to215-foot roll of film
Microfiche — small sheet of film, usually 4” 6”
Microfilm and Microfiche
Applications?
Libraries use to store back issues of newspapers, magazines, and genealogy records Large organizations use to archive inactive files Banks use to store transactions and canceled checks US Army uses to store personnel records
Advantages?
Reduce the amount of paper usage Inexpensive Have the longest life of any storage media
Microfilm and Microfiche
How do life expectancies of various media compare?
p. 7.29 Fig. 7-38 Next
Media Life Expectancies
Magnetic disks 3 to 5 years 20 to 30 years
CDs and DVDs discs 5 to 10 years 50 to 100 years
Microfilm 100 years 500 years
Media Type Guaranteed Life Potential LifeExpectancy Expectancy
Microfilm and microfiche have longest life of any storage media
Putting It All Together
What are recommended storage devices for home users?
p. 7.29 Fig. 7-39 Next
Home
3.5-inch high-density floppy disk drive
250 MB Zip drive 60 GB hard disk Internet hard drive CD or DVD drive Card reader
Putting It All Together
What are recommended storage devices for small office/home office (SOHO) users?
p. 7.29 Fig. 7-39 Next
3.5-inch high-density floppy disk drive
250 MB Zip drive 100 GB hard disk Internet hard drive CD or DVD drive External hard drive for backupSmall Office/
Home Office (SOHO)
Putting It All Together
What are recommended storage devices for mobile users?
p. 7.29 Fig. 7-39 Next
3.5-inch high-density floppy disk drive 2 GB PC Card hard disk or USB Drive 40 GB hard disk Internet hard drive CD or DVD drive Card reader External or removable hard disk for
backupMobile
Putting It All Together
What are recommended storage devices for large business users?
p. 7.29 Fig. 7-39 Next
3.5-inch high-density floppy disk drive
160 GB hard disk CD or DVD drive Microfilm or microfiche Smart card reader Tape driveLarge Business
Putting It All Together
What are recommended storage devices for power users?
p. 7.29 Fig. 7-39 Next
3.5-inch high-density floppy disk drive CD or DVD drive 160 GB hard disk Internet hard drive External or removable hard disk for
backup
Power
Summary of Storage
Floppy disksFloppy disks
Zip disksZip disks
Internal hard disksInternal hard disks
External hard disksExternal hard disks
Removable hard disksRemovable hard disks
CD-ROMsCD-ROMs
CD-RWsCD-RWs
DVD-ROMsDVD-ROMs
DVD+RWsDVD+RWs
TapeTape
PC CardsPC Cards
Flash memory cards and other miniature mobile storage media
Flash memory cards and other miniature mobile storage media
Microfilm and microficheMicrofilm and microfiche
Chapter 7 Complete