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).
Data is stored permanently in ROM, Data is not lost when the power goes off, Data in ROM cannot be changed.
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 desktopcomputer, 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.