8 8 C H A P T E R SECONDARY STORAGE
Mar 31, 2015
8888CH
AP
TE
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SECONDARY STORAGE
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Competencies
Distinguish between primary & secondary storage
Discuss the different types of storage mediaFloppy disk, hard disk and optical disk
Describe the traditional floppy disk and the high capacity floppy disks
Describe various types of hard disk devices
Internal HD , HD cartridge and HD packs.
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Competencies cont.
Describe ways to improve hard-disk operationsDisk caching, data compression
Describe the different types of optical disks
Describe other kinds of secondary storage devices .
Solid state storage, internet drives and magnetic tape
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Storage
Primary storageVolatileTemporary
It loses all of its contents when power to the system unit is shut off.
Secondary storageNonvolatile
Permanent
Writing : is the process of saving information.
Reading: is the process of accessing information.
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Secondary storage characteristics
Media ( actual physical material that holds the data and programs, Example: CD).
Capacity( measured how much a particular storage medium can hold) Storage devices (are hardware that reads data and program from storage media) Access speed ( measures the amount of time required by storage device to retrieve data and program).
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Secondary Storage Devices
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Floppy Disks
DiskettesFlexible disk and Floppies
The plastic disk inside the diskette cover is flexible
Portable storage mediaFloppy disk drives (FDD)
Store data and programs by altering the electromagnetic charges on the
Disk surface to represent ones and zeroes. Characters are represented by positive + and – charges using ASCII
code.
Traditional Floppy Disk
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Traditional Floppy Diskette 3.5 inch, 1.44 MB
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Types of Floppies
High capacity
Known as a floppy-disk cartridge
Require special disk drives
Three well known typesZip disks (Iomega)
100MB, 250MB, 750MB
HiFD disks (Sony) 200MB, 720MB, read and store data on 1.44MB disk
SuperDisks (Imation)240MB, 120MB
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Zip disks (Iomega)
SuperDisks (Imation)
HiFD disks (Sony)
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Hard Disks
Use thicker, metallic platters for storage
Faster than a floppy diskette
Large capacity
Sensitive instruments
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Materials that Cause a Head Crash A head crash occurs when a read/write head makes contact with the hard disk’s surface or with particles on its surface.
Three types of HD
Internal H.D
H.D Cartridge.
H.D Pack.
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Internal Hard Disk
Located inside system unit
Known as a fixed disk
Designated as the C drive
Advantages over floppies
Access speed
Capacity
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Hard-Disk Cartridges
Removable hard disks
Used to complement
internal hard disk
Capacities of 10 to 20
GB PC Card Hard Disks
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Peerless Disk
PC Card Hard Disks
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Hard-Disk Packs
Removable
Massive storage capacity
Common in mainframes
Used in Banks and credit cards companies.
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Hard-Disk Pack
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Performance Enhancements
Disk caching
Redundant arrays of inexpensive disks (RAID)expanding external storage
several hard disk drives are connected to one another.
File compression and decompression
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Optical Disks
Compact
Permanent storage
Optical disk use reflected light.
The 1s and 0s are represented by flat areas called lands and bumpy areas called pits.
Two common typesCD ( 650 MB to 1GB)
DVD ( 4.7 GB to 17 GB)
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Compact Disc
Optical formatFrom 650 MB to 1 GB capacityRotation speeds vary
It determines how fast data can be transferred from the CD24X or 24- speed CD drive can transfer 3.6 MB per second.
Types Read only: CD-ROMWrite once: CD-RRewriteable: CD-RWPicture CDs and Photo CDs
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Digital Versatile Disc
Digital Versatile Disk or Digital Video Disk (DVD)
Similar to CDs, but can store more data
TypesRead only
Write once
Rewritable
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DataPlayCD-R
Optical diskWrite once formatQuarter size
500 MB capacityHolds 5 hours of CD-quality sound
Use for storing and playing music files
Data play format ( search for it)
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Other Types of Secondary Storage
Solid-state storage
Internet hard drives
Magnetic tape
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Solid-State Storage
Flash memory cardsWidely used in notebook computers
Used to record MP3 music files
Key chain hard drives Key chain flash memory devices
Connects to a USB port
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Internet Hard Drives
Special service sites on the WEB provide users
With storage
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Magnetic Tape
External storage
Provides sequential accessInformation stored in sequence
Slower than disks which provide direct access
Magnetic tape streamers or tape cartridges used by both mainframes and microcomputers
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A Look to the FutureBlu-Ray Technology
New standard in storage
Blu-RayNew disks use blue laser light instead of the red laser light used in traditional CD players
Disks may ultimately hold Over 30GB on one-sided disks
Over 50GB on two-sided disks
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Key Terms
1.44 MB 31/2-inch disk (211)2HD (211)access time (210)C drive (213)capacity (210)CD (compact disc) (216)CD burner (216)CD-R (CD-recordable) (216)
CD-ROM (compact disc-read only memory) (216)
CD-RW (compact disc rewritable) (217)
DataPlay (220)
density (211)
direct access (221)
disk caching (213)
Diskette (210)
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Key Terms
disk (210)
DVD (digital versatile disc or digital video disc) (217)
DVD-RW or DVD+RW (DVD rewritable) (217)
DVD-R or DVD+R (DVD recordable) (217)
DVD-RAM (DVD-random-access memory) (217)
DVD player (217)
DVD-ROM (digital versatile disc-read only memory) (217)
Erasable optical disk (217)
file compression (215)
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Key Terms
file decompression (215)
fixed disk (212)
flash memory card (221)
flexible disk (211)
floppies (211)
floppy disk (210)
floppy disk drive (FDD) (210)
Floppy-disk cartridge (211)
hard disk (212)
hard-disk cartridge (213)
hard-disk pack (214)
head crash (212)
HiFD disk (212)
high capacity floppy disk (211)
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Key Terms
i-drive (221)
internal hard disk (212)
Internet hard drive (221)
jewel box (216)
key chain hard drives (221)
label (211)
land (216)
magnetic tape (222)
magnetic tape reel (222)
magnetic tape streamer (222)
media (210)
medium (210)
multiread (217)
multisession (217)
nonvolatile storage (210)
online storage (221)
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Key Terms
optical disk (216)
optical disk drive (216)
PC Card hard disk (214)
Photo CD (217)
Picture CD (217)
pit (216)
platters (212)
primary storage (210)
reading (210)
redundant arrays of inexpensive disks (RAID) (215)
removable hard disk (213)
rotational speed (216)
secondary storage (210)
secondary storage device (210)
sector (211)
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Key Terms
sequential access (221)
shutter (211)
single-session (217)
solid-state storage (220)
storage devices (210)
SuperDisk (212)
tape cartridge (222)
track (211)
volatile storage (210)
write-protection notch (211)
writing (210)
Zip disk (211)
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FAQs
What is the difference between primary storage and secondary storage?
What kinds of floppy disks are available?
What is the C drive of a computer?
When would I use a hard-disk cartridge?
What is the difference between a CD and a DVD?
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Discussion Questions
Discuss three ways to improve the performance of hard disks.
Describe the different types of compact discs.
Describe the different types of DVDs.
What are the advantages and disadvantages of using an Internet hard drive?
Describe solid state technology. Discuss the many uses for key chain flash memory devices.