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SECONDARY STORAGE

2

Storage

Primary storageVolatile

Temporary

Secondary storageNonvolatile

Permanent

Secondary storage characteristics

Media

Capacity

Storage devices

Access speed

3

Secondary Storage Devices

4

Floppy Disks

Diskettes

Floppies

Portable storage media

Floppy disk drives (FDD)

Traditional Floppy Disk

5

Traditional Floppy Diskette

6

Types of Floppies

High capacity

Known as a floppy-disk cartridge

Require special disk drives

Three well known typesZip disks ,100MB, 250MB, 750MB

HiFD disks, 200MB, 720MB

SuperDisks, 120MB, 240MB

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Hard Disks

Use thicker, metallic platters for storage

Faster than a floppy diskette

Large capacity

Sensitive instruments

8

Materials that Cause a Head Crash

9

Internal Hard Disk

Located inside system unit

Known as a fixed disk

Designated as the C drive

Advantages over floppies

Access speed

Capacity

10

Hard-Disk Cartridges

Removable hard disks

Used to complement

internal hard disk

Large capacity

PC Card Hard Disks

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Hard-Disk Packs

Removable

Massive storage capacity

Common in mainframes

12

Hard-Disk Pack

13

Performance Enhancements

Disk caching

Redundant arrays of inexpensive disks (RAID)

File compression and decompression

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Optical Disks

Compact

Permanent storage

Laser beams reflect off pits

Two common typesCD

DVD

15

Compact Disc

Optical format

From 650 MB to 1 GB capacity

Rotation speeds vary

Types Read only: CD-ROM

Write once: CD-R

Rewriteable: CD-RW

Picture 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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DataPlay

Optical disk

Write once format

Quarter size500 MB capacity

Holds 5 hours of CD-quality sound

Use for storing and playing music files

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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

Can be 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

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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

The End of Chapter 8