Pgdib hw devices

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Pgdib hw devices

  1. 1. Introduction With Hardware Devices Yogesh Tomar [email_address] , 9811521782 Copyright 2002 Prentice Hall, Inc.
  2. 2. Storing & Retrieving Information
  3. 3. Mass Storage and Files <ul><li>Programs and information (text, image, audio, video) are stored: </li></ul><ul><ul><li>Temporarily in RAM </li></ul></ul><ul><ul><li>Permanently in Mass Storage (disk and tape) </li></ul></ul>
  4. 4. Computer Files <ul><li>ASCII file </li></ul><ul><li>Data file </li></ul><ul><li>Document file </li></ul><ul><li>Spreadsheet file </li></ul><ul><li>Web page file </li></ul><ul><li>Source program file </li></ul><ul><li>Executable program file </li></ul><ul><li>Graphics file </li></ul><ul><li>Audio file </li></ul><ul><li>Video file </li></ul>.txt .mdb .vdp .xls .htm .gif .bmp .jpg .exe .tif .wav .mov
  5. 5. File Name Conventions 2001 Resume.doc separated by a period file extension (1 - 3 characters, optional) filename (up to 255 chars)
  6. 6. What do we do with files? <ul><li>Create, name, save </li></ul><ul><li>Copy, move, delete </li></ul><ul><li>Retrieve, update </li></ul><ul><li>Display, play, print </li></ul><ul><li>Execute </li></ul><ul><li>Download, upload </li></ul><ul><li>Export, import </li></ul><ul><li>Compress (zip/unzip) </li></ul><ul><li>Protect </li></ul>
  7. 7. Drive Designator Possibilities E: CD-ROM drive A: Floppy drive D: Zip drive System Unit C: Hard drive Courtesy of Imation Corporation
  8. 8. Physical Storage Process Storage medium Storage device <ul><ul><li>Sequential and/or Random </li></ul></ul><ul><ul><li>Write/Save </li></ul></ul><ul><ul><li>Read/Open </li></ul></ul>Storage process
  9. 9. Magnetic Disks Offline and Online Magnetic Disk Interchangeable Disks Hard/Fixed Disks Online only
  10. 10. Diskette Care <ul><li>Do store in protected spot, away from sun and magnets </li></ul><ul><li>Do remove before turning off computer </li></ul><ul><li>Do clean them periodically </li></ul><ul><li>Don’t expose to extreme temperatures </li></ul><ul><li>Don’t touch surface </li></ul><ul><li>Don’t remove if drive light is on </li></ul><ul><li>Don’t force it in/out of the drive </li></ul>
  11. 11. Hard Disks <ul><li>Anatomy: </li></ul><ul><ul><li>Recording surface </li></ul></ul><ul><ul><li>Multiple platters </li></ul></ul><ul><ul><li>Read/write head </li></ul></ul><ul><ul><li>Access arms </li></ul></ul>Courtesy of Seagate Technology
  12. 12. Fixed Hard Disk
  13. 13. Magnetic Disk Organization <ul><li>Disk Address </li></ul><ul><ul><li>Tracks/Sectors/Clusters </li></ul></ul><ul><ul><li>Cylinders </li></ul></ul><ul><li>Write data </li></ul><ul><ul><li>Magnetize disk’s thin coated surface </li></ul></ul><ul><li>Read data </li></ul><ul><ul><li>Sense absence or presence of a bit </li></ul></ul>
  14. 14. Magnetic Disk Organization <ul><li>VFAT: Virtual File Allocation Table </li></ul><ul><li>ScanDisk for lost clusters </li></ul><ul><li>Defragmentation </li></ul><ul><li>Formatting </li></ul><ul><li>Disk Speed </li></ul><ul><ul><li>Access time </li></ul></ul><ul><ul><li>Data transfer rate </li></ul></ul><ul><ul><li>Disk caching </li></ul></ul>
  15. 15. Backing Up Files <ul><li>Magnetic Tape used for: </li></ul><ul><ul><li>Backup or protection </li></ul></ul>
  16. 16. Computer Viruses <ul><li>Via Internet when downloading files </li></ul><ul><li>Via e-mail as attachments </li></ul><ul><li>Via diskette </li></ul><ul><li>Via computer networks </li></ul><ul><li>Use anti-viral program for your hard disks and UPDATE IT often </li></ul>
  17. 17. Backing Up Files <ul><li>Backup methods: </li></ul><ul><ul><li>Full </li></ul></ul><ul><ul><li>Selective </li></ul></ul><ul><ul><li>Modified files only </li></ul></ul><ul><li>Other backup options: </li></ul><ul><ul><li>Server computer </li></ul></ul><ul><ul><li>Notebook/desktop PC </li></ul></ul><ul><ul><li>CD-R or CD-RW </li></ul></ul><ul><ul><li>Interchangeable external hard disk </li></ul></ul>
  18. 18. Backing Up Files <ul><li>Internet and network servers </li></ul><ul><ul><li>Must be made fault-tolerant </li></ul></ul><ul><ul><li>Use RAID (Redundant Array of Independent Disks) for backup </li></ul></ul>
  19. 19. Optical Laser Devices Less sensitive to environment Cheaper than magnetic disks Large data capacity Optical Storage Spiraling Track Detector Pit Land Sector
  20. 20. Optical Disks: Write-Only <ul><li>CD-ROM </li></ul><ul><ul><li>Compact Disk: read only memory </li></ul></ul><ul><ul><li>Cannot be altered </li></ul></ul><ul><ul><li>Speeds: 32X, 40X or 75X (spin rate) </li></ul></ul><ul><ul><li>Jukeboxes </li></ul></ul><ul><ul><li>Capacity: 650 MB </li></ul></ul><ul><li>DVD-ROM </li></ul><ul><ul><li>Capacity: 4.7 GB to 17 GB </li></ul></ul><ul><ul><li>Backward compatible with CD-ROM </li></ul></ul>
  21. 21. Optical Disks: Read/Write <ul><li>CD-R </li></ul><ul><ul><li>Compact disk-recordable </li></ul></ul><ul><li>CD-RW </li></ul><ul><ul><li>Compact disk-rewritable </li></ul></ul><ul><ul><li>Will not work with older CD-ROM drives </li></ul></ul><ul><li>DVD-R </li></ul><ul><li>DVD-RAM </li></ul><ul><ul><li>Rewritable </li></ul></ul><ul><li>FMD-ROM </li></ul><ul><ul><li>Capacity up to 140 GB and backward compatible </li></ul></ul>
  22. 22. The End

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