ROM and RAM

Main store, or computer memory, is divided into ROM or Read Only Memory and RAM or Random Access Memory.

ROM

Read Only Memory cannot be changed by a program [program: An organised list of instructions that, when executed, causes the computer to behave in a predetermined manner. ] or user. ROM retains its memory even after the computer is turned off. For example, ROM stores the instructions for the computer to start up when it is turned on again. The operating system is loaded from the hard disk and stored in RAM whilst the machine is being used.

RAM

Random Access Memory is a fast temporary type of memory in which programs and datadata: information which has been organised or presented for analysis are stored whilst the computer is switched on. For example, when you load a word processing program [program: An organised list of instructions that, when executed, causes the computer to behave in a predetermined manner. ] it is loaded into RAM. The contents of the computer's screen is also held in RAM. If the computer loses power, data stored in RAM is lost.