88 chapter secondary storage. © 2005 the mcgraw-hill companies, inc. all rights reserved. 8-2...

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.