Revision2 Storage

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Revision of storage devices for GCSE

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Revision2 Storage

  1. 1. Revision Session 2
  2. 2. Storage Devices <ul><li>RAM </li></ul><ul><ul><li>Temporary storage </li></ul></ul><ul><ul><li>Stores current program </li></ul></ul><ul><ul><li>Random access memory </li></ul></ul><ul><ul><li>Read from or written to </li></ul></ul><ul><ul><li>Volatile </li></ul></ul><ul><ul><li>Power off = memory cleared </li></ul></ul><ul><ul><li>Internal memory </li></ul></ul>
  3. 3. Storage devices <ul><li>ROM </li></ul><ul><ul><li>Permanent storage </li></ul></ul><ul><ul><li>Read Only Memory </li></ul></ul><ul><ul><li>Contains the information to boot up the computer </li></ul></ul><ul><ul><li>Not lost when power down </li></ul></ul><ul><ul><li>Non-volatile </li></ul></ul><ul><ul><li>Internal memory </li></ul></ul>
  4. 4. Internal memory <ul><li>Small memory </li></ul><ul><li>Faster to access </li></ul>
  5. 5. Backing storage v internal <ul><li>Mass storage (BS) </li></ul><ul><li>Fast access (int) </li></ul><ul><li>Cheaper (BS) </li></ul>
  6. 6. Hard Disc <ul><li>Magnetic disc </li></ul><ul><li>Several disks on top of each other </li></ul><ul><li>Sterile </li></ul><ul><li>Tracks and sectors </li></ul><ul><li>Massive memory </li></ul><ul><li>Random access </li></ul>
  7. 7. Optical Disks <ul><li>Serial Access </li></ul><ul><li>Read or written to by laser </li></ul><ul><ul><li>CD-ROM </li></ul></ul><ul><ul><ul><li>Read only </li></ul></ul></ul><ul><ul><ul><li>650Mb </li></ul></ul></ul><ul><ul><ul><li>Created by laser and read by laser </li></ul></ul></ul><ul><ul><li>CD/R </li></ul></ul><ul><ul><ul><li>Read only </li></ul></ul></ul><ul><ul><ul><li>WORM </li></ul></ul></ul><ul><ul><ul><li>Laser created and laser read </li></ul></ul></ul>
  8. 8. continued <ul><ul><li>CD/RW </li></ul></ul><ul><ul><ul><li>Magnetico-optical </li></ul></ul></ul><ul><ul><ul><li>Read many write many </li></ul></ul></ul><ul><ul><ul><li>Created magnetically read optically </li></ul></ul></ul><ul><ul><li>DVD </li></ul></ul><ul><ul><ul><li>Digital Versatile Disk </li></ul></ul></ul><ul><ul><ul><li>17Gb </li></ul></ul></ul><ul><ul><ul><li>Use for films </li></ul></ul></ul><ul><ul><li>Blu-ray </li></ul></ul><ul><ul><ul><li>100+Gb </li></ul></ul></ul><ul><ul><ul><li>Used for HD </li></ul></ul></ul>
  9. 9. continued <ul><ul><li>Flash memory </li></ul></ul><ul><ul><ul><li>Non-volatile </li></ul></ul></ul><ul><ul><ul><li>Memory sticks, pen drives </li></ul></ul></ul><ul><ul><ul><li>USB </li></ul></ul></ul><ul><ul><ul><li>Small, stable and robust </li></ul></ul></ul><ul><ul><ul><li>Transfer data </li></ul></ul></ul><ul><ul><ul><li>Slower than RAM, faster than Hard Drive </li></ul></ul></ul><ul><ul><ul><li>Easily lost or broken </li></ul></ul></ul>
  10. 10. continued <ul><ul><li>Memory cards </li></ul></ul><ul><ul><ul><li>Flash </li></ul></ul></ul><ul><ul><ul><li>Use in digital cameras, MP3, mobile phones </li></ul></ul></ul><ul><ul><li>Magnetic tape </li></ul></ul><ul><ul><ul><li>Mass storage </li></ul></ul></ul><ul><ul><ul><li>Cheap </li></ul></ul></ul><ul><ul><ul><li>Access slow </li></ul></ul></ul><ul><ul><ul><li>Used in backups </li></ul></ul></ul><ul><ul><li>Floppy discs or zips </li></ul></ul><ul><ul><ul><li>1.4 Mb </li></ul></ul></ul><ul><ul><ul><li>Slow and unreliable </li></ul></ul></ul><ul><ul><ul><li>Zip = large floppy, 750Mb </li></ul></ul></ul>
  11. 11. Backing up data <ul><li>Don’t mix up with backing storage </li></ul><ul><li>A copy of the data onto a separate device used in case the original gets corrupted </li></ul><ul><li>Archive </li></ul><ul><ul><li>The removal of old data from a computer onto another device so that it can be referred to at a later date </li></ul></ul>

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