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ch7Wilson

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ch7Wilson

  1. 1. Chapter 7 - Storage By Chris Wilson
  2. 2. Storage <ul><li>Holds data, instructions, and information for future use. </li></ul><ul><li>Storage Medium (secondary storage) – The physical material on which a computer holds data. Ex: floppy disks, hard disks, CDs, DVDs, tape, ZIP disks, PC cards. </li></ul><ul><li>Capacity – Number of bytes a storage medium can hold. </li></ul>
  3. 3. Storage Device <ul><li>The computer hardware that records and/or retrieves items to and from storage media. </li></ul><ul><li>Writing – process of transferring data to a storage medium </li></ul><ul><li>Reading – process of transferring these items from a storage medium into memory. </li></ul><ul><li>Access time – amount of time it takes a storage device to locate an item on a storage medium. </li></ul>
  4. 4. Floppy Disks <ul><li>Floppy Disk (diskette) – A portable storage medium that consists of a thin, circular, flexible plastic Mylar film in a square plastic shell. </li></ul><ul><li>Magnetic media – Uses magnetic particles to store items in tracks and sectors. </li></ul><ul><ul><ul><li>Tracks – narrow recording band that forms a full circle on the disk </li></ul></ul></ul><ul><ul><ul><li>Sector – arc shaped storage locations that make the tracks. </li></ul></ul></ul>
  5. 5. ZIP Disk <ul><li>ZIP disk – A type of portable magnetic media that can store up to 500 times more than a standard floppy. </li></ul>
  6. 6. Hard Disk <ul><li>Hard Disk (hard disk drive) – A storage device that contains one or more inflexible, circular platters that store data, instructions, and information. </li></ul><ul><li>Platter – A 3.5 or 5.25in disk made of aluminum, glass, or ceramic and is coated with an alloy material that allows items to be recorded magnetically on it’s surface. </li></ul>
  7. 7. How a Hard Disk Works <ul><li>A platter will spin around at a rate of 5,400-7,200rpms, while a reader/writer head floats above the platter at ~two millionths of an inch. </li></ul><ul><li>Cache – location where frequently used items are store to improve efficiency. </li></ul>
  8. 8. Types of Hard Disks <ul><li>Internal – Permanently inside the CPU. </li></ul><ul><li>External – A separate freestanding hard disk that connects with a cable to a USB port. </li></ul>
  9. 9. Internet Hard Drives <ul><li>Internet Hard Drive – a service on the web that provides storage to computer users, usually for a minimal fee. </li></ul><ul><ul><ul><li>Allows users to to access files from any computer of device that has Internet access. </li></ul></ul></ul>
  10. 10. CDs and DVDs <ul><li>CDs and DVDs – storage media that consists of a flat, round, portable metal disc with a protective plastic coating. </li></ul><ul><ul><ul><li>An optical media that stores items by using microscopic pits (indentations) and lands (flat areas) </li></ul></ul></ul><ul><ul><ul><li>A high –powered laser light creates the pits, and a lower-powered laser reads items by reflecting light through the bottom of the disc. </li></ul></ul></ul>
  11. 11. CD-ROMs and CD-RWs <ul><li>CD-ROM – Optical disc that holds from 650MB to 1 GB of data. Users can read information from these discs but can not modify them. </li></ul><ul><li>CD-R (compact disc-recordable) – A multisession disc that users can record their own information once only </li></ul><ul><li>CD-RW (compact disc-rewritable) – A disc in which users can write, and then re-write new information. </li></ul>
  12. 12. DVD-ROM and DVD+RWs <ul><li>DVD-ROM (digital versatile disc-ROM or digital video disc) – an extremely high capacity optical disk capable of storing from 4.7 GB to 17 GB. </li></ul><ul><li>DVD+RW – A recordable version of DVD that allows users to erase and record more than 1,000 times. </li></ul>
  13. 13. Tape <ul><li>Tape – a magnetically coated ribbon of plastic capable of storing large amounts of data and information at a low cost. </li></ul><ul><li>Tape drive – Device that reads and writes data and information on tape. </li></ul>
  14. 14. PC Cards and Types of Miniature Storage Media <ul><li>PC Card – A thin credit-card sized device that fits into a PC Card slot to add storage or other capabilities to a desktop or notebook computer. </li></ul><ul><ul><ul><li>Examples : PDA;s, digital cameras, music plaers. </li></ul></ul></ul><ul><li>Miniature mobile storage media – Compact flash, Memory stick, Secure digital, Smart Media. </li></ul>
  15. 15. Microfilm and Microfiche <ul><li>Microfilm – A 100-215ft roll of film used to store back issues of newspapers, magazines, and records. </li></ul><ul><li>Microfiche – A small sheet of film usually about 4 by six inches used in the same fashion as microfilm. </li></ul>

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