Computers: Information Technology in Perspective By Long and Long Copyright 2002 Prentice Hall, Inc. Computers: Information Technology in Perspective Prof: Jad Matta Copyright 2002 Prentice Hall, Inc.

Computers: Information Technology in Perspective By Long and Long Copyright 2002 Prentice Hall, Inc. Storing & Retrieving Information Chapter 4

Quit See What’s New 4.3 Monthly Technology Update

Quit Mass Storage and Files  Programs and information (text, image, audio, video) are stored:  Temporarily in RAM  Permanently in Mass Storage (disk and tape) 4.4

Quit Computer Files  ASCII file  Data file  Document file  Spreadsheet file  Web page file  Source program file  Executable program file  Graphics file  Audio file  Video file.txt.mdb.vdp.xls.htm.gif.bmp.jpg.exe.tif.wav.mov

Quit File Name Conventions 2001 Resume.doc separated by a period file extension (1 - 3 characters, optional) filename (up to 255 chars)

Quit What do we do with files? 4.7  Create, name, save  Copy, move, delete  Retrieve, update  Display, play, print  Execute  Create, name, save  Copy, move, delete  Retrieve, update  Display, play, print  Execute  Download, upload  Export, import  Compress (zip/unzip)  Protect  Download, upload  Export, import  Compress (zip/unzip)  Protect

Quit E: CD-ROM drive A: Floppy drive D: Zip drive System Unit Drive Designator Possibilities C: Hard drive Courtesy of Imation Corporation

Quit Physical Storage Process Storage medium Storage device –Sequential and/or Random –Write/Save –Read/Open –Sequential and/or Random –Write/Save –Read/Open Storage process

Quit Offline and Online Magnetic Disks Magnetic Disk Hard/Fixed Disks Online only Interchangeable Disks

Quit The Diskette  3.5” Floppy: 1.44 MB  SuperDisk: 120 MB  HiFD disk: 200 MB  Zip Disk: 100 or 250 MB Disk density

Quit Diskette Care  Do store in protected spot, away from sun and magnets  Do remove before turning off computer  Do clean them periodically  Don’t expose to extreme temperatures  Don’t touch surface  Don’t remove if drive light is on  Don’t force it in/out of the drive 4.12

Quit Hard Disks  Faster and more storage than diskettes  10 GB to >75 GB permanently installed  1-2 GB interchangeable Jaz®  Anatomy:  Recording surface  Multiple platters  Read/write head  Access arms 4.13 Courtesy of Seagate Technology

Quit Fixed Hard Disk 4.14

Quit Head Crash

Quit Magnetic Disk Organization  Disk Address  Tracks/Sectors/Clusters  Cylinders  Write data  Magnetize disk’s thin coated surface  Read data  Sense absence or presence of a bit

Quit Magnetic Disk Organization 4.17  VFAT: Virtual File Allocation Table  ScanDisk for lost clusters  Defragmentation  Formatting  Disk Speed  Access time  Data transfer rate  Disk caching

Quit Computer Viruses  Via Internet when downloading files  Via as attachments  Via diskette  Via computer networks  Use anti-viral program for your hard disks and UPDATE IT often! 4.18

Quit Backing Up Files  Magnetic Tape used for:  Backup or protection  Archiving  Tape backup units (TBUs)  Data cartridge  Inexpensive and can store > 1 GB  Magnetic Tape used for:  Backup or protection  Archiving  Tape backup units (TBUs)  Data cartridge  Inexpensive and can store > 1 GB 4.19

Quit Backing Up Files  Backup methods:  Full  Selective  Modified files only  Other backup options:  Server computer  Notebook/desktop PC  CD-R or CD-RW  Interchangeable external hard disk 4.20

Quit Backing Up Files  Internet and network servers  Must be made fault-tolerant  Use RAID (Redundant Array of Independent Disks) for backup 4.21

Quit Optical Laser Devices Spiraling Track Detector Pit Land Sector Less sensitive to environment Cheaper than magnetic disks Large data capacity Optical Storage

Quit Optical Disks: Write-Only  CD-ROM  Compact Disk: read only memory  Cannot be altered  Speeds: 32X, 40X or 75X (spin rate)  Jukeboxes  Capacity: 650 MB  DVD-ROM  Capacity: 4.7 GB to 17 GB  Backward compatible with CD-ROM

Quit Optical Disks: Read/Write  CD-R  Compact disk- recordable  CD-RW  Compact disk- rewritable  Will not work with older CD-ROM drives  DVD-R  DVD-RAM  Rewritable  FMD-ROM  Capacity up to 140 GB and backward compatible

Quit Cost Comparison 4.25 RAM - $1/Mb Hard disk < $.1/Mb CD - fraction of $.01/Mb

Computers: Information Technology in Perspective By Long and Long Copyright 2002 Prentice Hall, Inc. Storing & Retrieving Information The End