Copyright Prentice-Hall, Inc. 2001

Storing & Retrieving Storing & Retrieving InformationInformation

Chapter Chapter 77

4-2See What’s NewSee What’s New

Monthly Monthly Technology Technology

UpdateUpdate

4-3Computer FilesComputer FilesData Files Program Files

Word Processing Document

Pictures Card Files or Lists

Spreadsheets

Sound Clips

Word

Excel

SoundRecorder

Paint

Access

4-4File Name ConventionsFile Name Conventions

2000 Resume.DOC

separated by a periodseparated by a periodseparated by a periodseparated by a period

file extensionfile extension(1 - 3 characters, optional)(1 - 3 characters, optional)

file extensionfile extension(1 - 3 characters, optional)(1 - 3 characters, optional)

filenamefilename(up to 255 chars)(up to 255 chars)

filenamefilename(up to 255 chars)(up to 255 chars)

4-5What do we do with files?What do we do with files?

Create, name, saveCreate, name, save Copy, move, deleteCopy, move, delete Retrieve, updateRetrieve, update Display, play, printDisplay, play, print

Download, uploadDownload, upload Export, importExport, import CompressCompress ProtectProtect

4-7Physical Storage ProcessPhysical Storage Process

Storage mediumStorage medium

Storage deviceStorage device

–Sequential and/or Random

–Write/Save

–Read/Open

–Sequential and/or Random

–Write/Save

–Read/Open

Storage processStorage process

4-8

OfflineOfflineandand

OnlineOnline

OfflineOfflineandand

OnlineOnline

Magnetic DisksMagnetic Disks

MagneticMagneticDiskDisk

Interchangeable DisksInterchangeable Disks

OnlineOnlineonlyonly

OnlineOnlineonlyonlyHard/Fixed DisksHard/Fixed Disks

4-9Interchangeable DisksInterchangeable Disks

3.5” Floppy: 1.44 MB3.5” Floppy: 1.44 MB SuperDisk: 120 MBSuperDisk: 120 MB Zip Disk: 100 or 250 MBZip Disk: 100 or 250 MB Disk densityDisk density

4-10Hard DisksHard Disks

Faster and more storage than diskettesFaster and more storage than diskettes 4 GB - 75 GB permanently installed4 GB - 75 GB permanently installed 1-2 GB interchangeable Jaz®1-2 GB interchangeable Jaz® Read/write head and access armsRead/write head and access arms

Courtesy of Seagate Technology

4-11Head CrashHead Crash

4-13Magnetic Disk AccessMagnetic Disk Access

VFAT: Virtual File Allocation TableVFAT: Virtual File Allocation Table DefragmentationDefragmentation FormattingFormatting Disk-Access TimeDisk-Access Time Data Transfer RateData Transfer Rate

Disk cachingDisk caching

4-14Diskette CareDiskette Care

Do backup Do backup Do remove before turning off computer Do remove before turning off computer Avoid cold or hot or direct sunAvoid cold or hot or direct sun Avoid magnetsAvoid magnets Don’t touch surfaceDon’t touch surface Don’t remove if drive light is onDon’t remove if drive light is on

4-15Computer VirusesComputer Viruses

Via Internet when downloading filesVia Internet when downloading files Via email as attachmentsVia email as attachments Via diskette Via diskette Via computer networksVia computer networks Use anti-virus program for your hard Use anti-virus program for your hard

disksdisks

4-16Back Up and Rest Easy Back Up and Rest Easy

Magnetic Tape used for:Magnetic Tape used for: Backup or protectionBackup or protection ArchivingArchiving File portabilityFile portability

Pros and ConsPros and Cons Sequential access - slowSequential access - slow CheapCheap

Or use an interchangeable diskOr use an interchangeable disk

4-17Optical Laser DevicesOptical Laser Devices

OpticalOpticalStorageStorage

Spiraling Track

Detector

Pit

Land

Sector

4-18Optical Device: CD-ROMOptical Device: CD-ROM

Compact Disk: Read only memoryCompact Disk: Read only memory Capacity: 680 MBCapacity: 680 MB 24X, 32X and 40X speeds24X, 32X and 40X speeds Jukeboxes Jukeboxes

4-19Optical Device: DVDOptical Device: DVD

Digital VideodiskDigital Videodisk Capacity: 10 GBCapacity: 10 GB

Backwards compatible with CD-ROMBackwards compatible with CD-ROM

4-20Newest Optical DevicesNewest Optical Devices

CD-RCD-R Recordable onceRecordable once

CD-RWCD-RW Rewritable : Random accessRewritable : Random access

WORMWORM Write once, read many timesWrite once, read many times

Photo Courtesy of Hewlett-Packard Company

4-21Cost ComparisonCost Comparison

RAM - $1/MbRAM - $1/MbRAM - $1/MbRAM - $1/Mb

Hard disk - $.1/MbHard disk - $.1/MbHard disk - $.1/MbHard disk - $.1/Mb

CD - fraction of $.01/MbCD - fraction of $.01/MbCD - fraction of $.01/MbCD - fraction of $.01/Mb

Copyright Prentice-Hall, Inc. 2001

End of Chapter End of Chapter 77

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