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Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
Computers12 Ch6
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Computers12 Ch6

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  • 1. Chapter 6 B.M.H Storage and Multimedia
  • 2. Index
    • Secondary Storage
    • Magnetic Disk Storage
      • Diskettes
      • Hard Disks
    • Data Organization on a Disk
  • 3. Computer System
    • Hardware
      • Input devices
      • Output devices
      • Processor and Memory
      • Secondary Storages
    • Software
      • System SW
      • Applications SW
    • People
  • 4. Computer system Input Processing Output Secondary Storage
  • 5. Secondary Storage
    • Benefits
      • Space
      • Reliability
      • Convenience
      • Economy
  • 6. Secondary Storage
    • Types
      • Magnetic disk storage
        • Diskettes, Hard Disks
      • Magnetic tape storage
      • Optical disk storage
        • CD, DVD
  • 7. Magnetic Disk Storage
    • Magnetic media
      • a technology of representing data as magnetized spots on the surface of a spinning disk
        • A magnetized spot : 1 bit
        • The absence of such a spot : 0 bit
  • 8. Magnetic Disk Storage
    • Reading data from the disk
      • Converting the magnetized data to electrical impulses
    • Writing data to disk
      • Converting electrical impulses from the processor to magnetized spots on the disk
  • 9.  
  • 10. Magnetic Disk Storage
    • Types
      • Diskettes
      • Hard disks
  • 11. Diskettes
    • Made of flexible Mylar
    • Coated with iron oxide,
      • a substance that can be magnetized
    • Types
      • The standard floppy disk :
        • 3 1/2-inch diskette 1.44 megabytes of data
      • Two new high-capacity drives :
        • 120 or 200 megabytes per disk
      • Iomega’s Zip drive :
        • 250-megabyte disks
        • Is not compatible with 31/2-inch diskettes
  • 12.  
  • 13.  
  • 14.  
  • 15.  
  • 16. Hard Disk
    • A rigid platter coated with magnetic oxide
    • Sizes : various
    • Capacity for PC
      • Older ones : hundreds of megabytes
      • New ones : tens of gigabytes of storage
  • 17. Hard Disk
    • Disk pack
      • assembles several platters
      • Components
        • Platters
        • Access arms
        • Read/write heads
  • 18.  
  • 19.  
  • 20.  
  • 21. Hard Disks in Groups
    • RAID
      • ( R edundant A rray of I ndependent d isks)
      • Uses a group of small hard disks that work together as a unit
      • Used for storage system to be safe
      • Types
        • RAID level 1
        • Higher levels of RAID
  • 22. Data organization on a disk
    • Several characteristics
      • Track
      • Sectors
      • Clusters
      • Cylinder
  • 23.  
  • 24.  
  • 25.  
  • 26.  
  • 27.  
  • 28.  
  • 29. Disk drive
    • A device that allows data to be read from a disk or written to a disk
    • The performance
      • One measure : average access time
      • Another measure : data transfer rate
  • 30.  
  • 31. Access Time
    • The time needed to access data directly on disk
    • Three primary factors
      • Seek time
      • Head switching
      • Rotational delay
    • Average access time
      • Usually measured in milliseconds (ms)
      • Current hard disk drives : Under 10ms
  • 32. Data transfer
    • The process of transferring data between memory and the place on the disk track
      • Writing : from memory to the track
      • Reading : from the track to memory
    • Data transfer rate
      • Tells how fast data can be transferred once it has been found
      • Usually be measured in megabytes of data per second
  • 33. Disk Cache
    • Used to improve the effective access time
    • Memory cache

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