ROM and Secondary Memory not yet done

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  • Created by: Noye
  • Created on: 22-04-13 14:57
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  • Memory
    • Definition: Components that store information, data and instructions
      • Memory access speed from fastest to slowest
        • Processor
          • Cache
            • Main Memory
              • Virtual Memory
    • RAM
      • Used in MAIN MEMORY
      • Random Access Memory
        • Can be written to ANYWHERE  in the memory space and at ANY TIME
        • Volatile
      • To run a program it must be LOADED FROM THE HARD DISK to the main memory.
        • Reading  from and writing to the hard disk is SLOW. Main memory makes it FASTER
      • DATA is also loaded WHILE THE PROGRAM IS RUNNING
      • Acts as TEMPORARY STORAGE while programs are running
    • Virtual Memory
      • On the HARD DISK
      • Computers can be configured so part of the hard disk behaves like main memory
        • This happens when there is not enough main memory to run a program
        • Can store parts of programs, but parts currently being run must be in main memory
          • Inefficient as sometimes more fetch-execute cycles are spent swapping sections between main memory and virtual memory
        • Much slower  than actual main memory
    • ROM
      • Read Only Memory
        • Non-Volatile
        • Contents can't be written over
      • Bootstrap Loader
        • Loads the operating system
    • Secondary Memory
      • LONG TERM, NON-VOLATILE storage
      • Includes: Hard Disk, memory sticks, floppy disks, tapes, DVDs and CDs
  • Contents can't be written over


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