Memory and secondary storage

• RAM is high speed, volatile memory.
• What kind of memory is RAM?

  Main memory that can be read and written to.
• What is stored in main memory (RAM)?

  Data, files and programs that are currently being used.
• When RAM is full, data that hasn't been used recently is moved to secondary storage (virtual memory).
• Why is using virtual memory slow?

  Because data needs to be transferred back to RAM in order for it to be read.
• Why might virtual memory be needed?

  There are too many applications open at once or a memory-intensive application is being used.
• Using virtual memory can cause a computer to be..

  slow to respond
• What does the ROM do?

  Contains all the instructions a computer needs to boot up, known as BIOS.
• What happens when the computer is booted up?

  CPU reads the BIOS from the ROM.
• What are HDDS?

  Magnetised metal disks that spin thousands of times per second.
• How is data stored in HDDs?

  magnetically with moving parts
• What are SSDs?

  Storage devices with no moving parts which is flash storage
• Give some examples of flash storage

  USB pen drives

  memory cards
• Give advantages of HDDs compared to SSDs.

  Cheaper

  Have a higher capacity than SSDs

  Longer read/write life
• Give advantages of SSDs compared to HDDs.

  Faster

  Don't need defragmenting

  Shock proof

  Silent
• Give disadvantages of HDDs.

  Can be damaged

  Needs defragmenting

  Noisey
• Give disadvantages of SSDs.

  More expensive

  Limited read/write life
• Give examples of optical disks.

  CD

  DVD

  Blu-ray
• Give advantages of optical disks.

  Cheap

  Portable

  Robust/shock proof
• What are magnetic tapes used for?

  Used by large organisations in archive libraries to store huge amounts of data.
• Give advantages of magnetic tapes.

  Large storage

  low cost per GB

  Fast once in correct place to begin read/writing