1.2.1. Memory

• What does RAM stand for?


  Random access memory.
• What does the RAM do?

  It holds data and programs currently in use.
• Is RAM volatile?


  Yes, meaning that it loses data without power.
• How big are RAMs?


  They have quite large capacity for primary storages, of about 4 GB to 16 GB.
• Describe the content of the RAM


  It is frequently changed.
• What does ROM stand for?


  Read only memory.
• What does the ROM do?


  It holds start up instructions for computers including BIOS and boot strap files.
• Is ROM volatile?

  No - meaning that it keeps the data even when there's no power.
• How big are ROMs?


  They have small capacity of about 4 MB.
• Describe the content of ROM:


  They do not change.
• What is virtual memory?


  Using a section of the hard drive or secondary storage as though it was RAM.
• When is virtual memory used?


  When you don't have enough space in RAM to open a new program.
• What is the purpose of virtual memory?


  It allows you to still open and run programs when you have ran out of RAM.
• How does virtual memory work?


  Files in the RAM that aren't being used are moved into the virtual memory, freeing up space for the new program.
• Can virtual memory be accessed from the CPU?


  No, the CPU cannot use data in the VM, therefore data must be swapped back to RAM.
• What is a problem with virtual memory?


  Disk thrashing - if too much VM is used, CPU can spend more time swapping data than doing processing.
• What is primary storage?


  Also known as memory, used for data currently in use and to start the computer.
• What does volatile mean?


  That it loses its content when the power is switched off.
• What is a boot strap?


  A program that loads the operating system.
• What is the BIOS?


  A program that tests basic hardware works and starts the boot process.
• What is cache?


  Small, fast memory that holds the most frequently used instructions.
• What is disk thrashing?


  Spending more time swapping data between VM and RAM than processing.
• What do hard drives do?


  They hold programs and files permanently when they are not in use.
• Why can CPU only fetch data from memory like RAM?


  Storage is too slow to access.