Topic 2

• Differences between primary and secondary storage

  
• Why do computers need primary storage

  -Primary storage holds the data and instructions that the CPU needs to access whilst the computer is turned on
• What is RAM


  -Random Access Memory

  -Primary storage

  -Directly connected to the CPU and holds the data and instructions that are currently in use

  -Volatile

  -Very fast working memory

  -Read/write which means data can be read from and written to
• RAM is volatile, what does this mean?


  The contents of the RAM will be lost when the power is turned off
• What is ROM


  -Read Only Memory

  -Primary storage

  -Holds the first instructions a computer needs to start up (Bootstrap)

  -Contains the BIOS

  -Read only

  -Non-volatile
• RAM vs ROM


  RAM: larger capacity, temporary, volatile, faster, and writable. ROM: smaller capacity, permanent, non-volatile, slower, and non-writable.
• What is virtual memory


  An extension of primary storage (RAM) located on secondary storage
• When is virtual memory used


  When the RAM is closed to being full, virtual memory is used so that the computer remains operational
• Virtual memory characteristics


  -Virtual memory is much slower than RAM and its use will impact negatively on system performance

  -To avoid the use of virtual memory, increase the size of the RAM
• Why do computers need secondary storage


  -For long term storage of programs and data that are not currently in use.

  -ROM is read only and RAM is volatile so secondary storage is needed

  -Secondary storage holds the programs and data whilst the computer is turned off (non-volatile)
• What are the three types of storage

  Magnetic

  Optical

  Solid state
• Magnetic storage advantages and disadvantages

  
• Solid state storage advantages and disadvantages

  
• Optical storage advantages and disadvantages