Copyright Prentice-Hall, Inc Storing & Retrieving Information Chapter 7

4-2 See What’s New Monthly Technology Update

4-3 Computer Files Data Files Program Files Word Processing Document Pictures Card Files or Lists Spreadsheets Sound Clips Word Excel Sound Recorder Paint Access

4-4 File Name Conventions 2000 Resume.DOC separated by a period file extension (1 - 3 characters, optional) filename (up to 255 chars)

4-5 What do we do with files? l Create, name, save l Copy, move, delete l Retrieve, update l Display, play, print l Download, upload l Export, import l Compress l Protect

4-6 E: CD-ROM drive A: Floppy drive D: Zip drive System Unit Drive Designator Possibilities C: Hard drive Courtesy of Imation Corporation

4-7 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

4-8 OfflineandOnlineOfflineandOnline Magnetic Disks MagneticDisk Interchangeable Disks OnlineonlyOnlineonly Hard/Fixed Disks

4-9 Interchangeable Disks l 3.5” Floppy: 1.44 MB l SuperDisk: 120 MB l Zip Disk: 100 or 250 MB l Disk density

4-10 Hard Disks l Faster and more storage than diskettes l 4 GB - 75 GB permanently installed l 1-2 GB interchangeable Jaz® l Read/write head and access arms Courtesy of Seagate Technology

4-11 Head Crash

4-12 How Is Data Recorded? l Disk Address u Tracks/Sectors/Clusters u Cylinders l Write data u Magnetize disk’s thin coated surface l Read data u Sense absence or presence of a bit

4-13 Magnetic Disk Access l VFAT: Virtual File Allocation Table l Defragmentation l Formatting l Disk-Access Time l Data Transfer Rate u Disk caching

4-14 Diskette Care l Do backup l Do remove before turning off computer l Avoid cold or hot or direct sun l Avoid magnets l Don’t touch surface l Don’t remove if drive light is on

4-15 Computer Viruses l Via Internet when downloading files l Via as attachments l Via diskette l Via computer networks l Use anti-virus program for your hard disks

4-16 Back Up and Rest Easy l Magnetic Tape used for: u Backup or protection u Archiving u File portability l Pros and Cons u Sequential access - slow u Cheap l Or use an interchangeable disk

4-17 Optical Laser Devices OpticalStorage Spiraling Track Detector Pit Land Sector

4-18 Optical Device: CD-ROM l Compact Disk: Read only memory l Capacity: 680 MB l 24X, 32X and 40X speeds l Jukeboxes

4-19 Optical Device: DVD l Digital Videodisk l Capacity: 10 GB l Backwards compatible with CD-ROM

4-20 Newest Optical Devices l CD-R u Recordable once l CD-RW u Rewritable : Random access l WORM u Write once, read many times Photo Courtesy of Hewlett-Packard Company

4-21 Cost Comparison RAM - $1/Mb Hard disk - $.1/Mb CD - fraction of $.01/Mb

Copyright Prentice-Hall, Inc End of Chapter 7 Interactive Study Guide