Unit 1 Lesson 4: Storage

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  • Created on: 19-04-19 15:37
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  • UNIT 1 LESSON 4: STORAGE
    • Types of Storage
      • secondary storage
        • SSD
          • Solid State Drive
        • HDD
          • Hard Disk Drive
      • primary storage
        • ROM
          • Read Only Memory
        • RAM
          • Random Access Memory
      • offline secondary storage
        • USB flash memory
        • BluRay
        • removable HDD
        • DVD
        • magnetic tape
        • CD
    • Storage Methods
      • optical
        • laser read and write data using light
      • magnetic
        • mechanical parts move over the disks surface to read and write data magnetically
      • solid state
        • data is recorded onto solid memory chips without any moving parts
    • SSD
      • disadvantages
        • less storage capacity / physical size than traditional hard disks
        • expensive at present
      • advantages
        • very fast read / write speeds
        • no moving parts
        • no noisy fan
        • highly durable
        • faster start up times
      • information
        • uses electrical current
        • non volatile
        • type of RAM
        • very fast
        • Solid State Drive
        • no mechanical or moving parts
        • flash memory
        • trapped = 0, not trapped = 1
    • Optical Storage
      • disadvantages
        • less storage capacity compared to other types
        • easily damaged / scratched
        • requires a CD reader
        • slow write speeds
      • advantages
        • very easily portable
        • cheap
        • take up little space physically
      • information
        • a laser beam passes over the pits and lands, the level of reflection is measured
        • data is stored as pits and lands burnt into a spiral track circulating outwards from the centre
        • 0's and 1's can b derived from reflections or no reflections
    • Magnetic Disks
      • advantages
        • vast storage capability
        • cheap
        • fast write speed
      • information
        • have a large storage capacity
        • can get portable ones - for backing up
        • disk heads mounted on mechanical arms read and write the data
        • used for transferring data
        • each track is divided into sectors
        • can store several GB of data
        • disk contains concentric circles called tracks
      • disadvantages
        • sealed unit due to disk head and platter precision
        • durability an issue
        • not very portable
        • lots of mechanical parts
    • Flash Memory
      • information
        • read and write
        • non volatile
        • used as secondary storage in desktops and phones
      • advantages
        • no moving parts
        • portable
        • durable
        • low cost
    • Factors to consider when choosing storage
      • portability
      • durability
      • reliability
      • speed

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