Unit 1.2 - Memory

Unit 1.2 - Memory

1. Virtual Memory

   • Virtual Memory is simulated memory on the hard drive
   • It is used for applications which the RAM cannot support, usually because it is too full.
   • Disk Thrashing is the process of files being moved from cache to RAM to the Hard Drive
   • Much slower than RAM, writing to a hard drive takes longer than writing to RAM

2. RAM - Random Access Memory

   • SRAM - Static RAM
     • Retains bits of data in it;s memory as long as power is supplied
     • Does not have to be refreshed
   • DRAM - Dynamic RAM
     • Typically used for data or program coding
     • Has to refresh periodically
   • Contains the data and programs currently in use
   • Loses the data as the power is lost - Volatile

3. ROM - Read Only Memory

   • Retains the information if power is disconnected - Non Volatile
   • The location of the POST (Power On Self Test) sequence
     • Makes sure the components are present and functional
     • Uses BIOS (Basic Input Output System) performance checks
     • Once completed successfully, the OS boots
   • Contains BIOS (Basic Input/Output System). A type of firmware that contains instructions to start up the computer