Types of Memory Storage

• Memory
  • Internal devices access directly
  • Applications store
  • Files
  • Storage devices
    • Removable Access
      • Devices can be lost
    • Data Drop
      • Solved this issues
        • Bluetooth
        • Cloud Storage
  • Internal memory
    • Registers
      • Part processer
  • Memory Cache
    • External processor
    • Regularly accessed by computer
• Primary
  • Directly accessed by CPU
  • Random Access Memory (RAM)
    • In some form of RAM
    • RAM data is accessible compared secondary devices
      • Written or read
      • Change data
      • Store, Files, Application run
      • Volatile
        • It is lost when you the turn off the computer
    • Larger the ram, the faster the computer
    • RAM never runs out of memory
      • Instead it slower
    • Continually new data is load
      • Old data in the RAM is overwrite
  • DRAM (dynamic RAM)
    • Chip has multiple transistors and capacitors
    • Capacitor 0 or 1
    • Transistors act like switches
      • Circulation control to Capacitors
    • Has to be refreshed regularly
    • Capacitor re-charge 15 microseconds
      • Capacitor leak
    • Benefits
      • Less expensive
      • Less power consume
      • Higher memory capacity SRAM
  • Static RAM (SRAM)
    • No constantly refreshing required
    • Flip Flops
      • Bit of memory held
    • SRAM faster than DRAM
      • SRAM data access speed 25 nanoseconds
      • DRAM data access speed 60 nanoseconds
  • Read Only Memory (ROM)
    • Non-volatile
      • Power turn off does not lose data
      • Permanent Memory Devices
        • Contents can’t easily be changed
      • Data required by computer start up, boot
        • BIOS – Basic Input Output System
    • PROM
      • Programmable read-only memory (PROM)
      • Altered once
      • Fuses
      • Fuse burning is used matrix which data words
    • EPROM
      • Erasable Programmable read-only memory (EPROM)
        • Floating gate transistors and capacitors
    • Embedded System
      • Microprocessors devices – efficiently
      • Benefits
        • Small size easy to install
        • Low cost
        • Dedicated to one type of task – dedicated, processing power less
        • Power less consume
        • Reaction time is fast
        • Mass produce
      • Drawbacks
        • Upgrade issues
        • Troubleshooting
        • Interface can be complex
        • Devices can be hackers
        • Throw away instead repair
• Secondary Storage Devices
  • Not directly accessible from the CPU
  • Non-volatile
  • Space larger compared primary memory
  • Operating system contained in it.
  • 3 types
    • Hard Disk Drives (HDD)
      • Common
      • Digital format – magnetic surfaces – platters
      • Speed spin speedily (7000 times a second)
      • Heads – read/ write functions performed
      • Two surfaces to store data
      • Center to edge (50 times in a second)
      • Sectors and tracks
      • Slow data access
      • Latency
        • Time taken data extract write multiple sectors tracks
      • Fragmentation
        • Defragmentation software
      • Removable Hard Disk