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Storage

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Objectives

1. Floppy and hard disks

2. Cartridges and disk packs

3. Performance enhancements

4. Compact disks

5. Specialized disks

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Secondary Storage

• Save information

• Permanent storage

• Temporary storage

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Floppy Disks

• Removable

• Write-protect

• Parts– Tracks– Sectors

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New Standards

• Zip Disks– 250 MB

• SuperDisks– 120 MB

• HiFD disks– 200 MB

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Hard Disks

• Metallic disks

• Fast information

• Read-write heads

• Three types– internal hard disk

– hard-disk cartridge

– hard-disk pack

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Human hair

dust particle

fingerprint

smoke particle

disk head

disk surface

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Internal Hard Disk

• Inside system unit

• Advantage over

floppy disks

• Capacity: 80 gig

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Hard-disk Cartridges

• Easy removal

• Complements internal

– JAZ from Iomega

– SPARQ from SyQuest

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Hard-disk Packs

• Removable

• Massive storage capacity

• Common in mainframes

• Resembles stack of vinyl records

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Performance Enhancements

• Disk caching

• Redundant arrays of inexpensive

disks (RAID)

• File compression and decompression

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• Compact

• Permanent storage

• Laser beams reflect off pits

• Three types

Optical Disks

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CD-ROM

• Compact disc-read-only memory

• Not written to

• 650 MB capacity

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CD-R & CD-RW

• CD-Recordable or WORM

• CD-RW or rewritable optical discs

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CD-R for Music

• Download from Internet

• Arrange and play music

• Create custom CD-R or

CD-RW

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DVD

• Digital Versatile Disk or Digital

Video Disk

• Types– DVD-ROM– DVD-R – DVD-RAM or DVD-RW

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Magnetic Tape

• Fast, direct access

• Sequential access

• Storage and backup

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A Look to the Future

• Near-field recording devices

• Holographic storage systems

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