Copyright Prentice-Hall, Inc. 2001 Storing & Retrieving Storing & Retrieving Information Information Chapter Chapter 7 7
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
Interactive Interactive Study GuideStudy Guide