Computer Structure

By Shannon MacLeod

Backing Storage

  • People often get confused between main memory and backing storage, they are not the same.
  • Main memory is located inside the computer system. It can either be RAM or ROM.
  • Backing storage is outside the main processor, e.g. Hard Drives, CD/DVD drives, USB Flash Memory (Pen Drives).


ROM (Read Only Memory)

ROM

  • ROM is used to store a small part of the operating system called the bootstrap loader.
  • Data is stored permanently in ROM.
  • Data is not lost when the power goes off.
  • Data in ROM cannot be changed.


RAM (Random Access Memory)

  • This is where the operating system is stored; it also holds all programs and data. You can purchase additional RAM chips and install them in your desktop computer, which normally speeds up multi-tasking.
  • The processor can write to and read from RAM at high speed.
  • Data held in RAM can be changed.
  • All data in RAM is lost when the power is switched off.


Embedded Systems

  • Small scale computers, with their own processors and memory.
  • Built into machines to carry out a job.
  • Can be found in many products such as:
  • Digital cameras
  • Mobile phones
  • Cars
  • Washing Machines