Primary Storage or Main Memory (RAM)

Primary Storage or Main Memory (RAM) :-

Primary storage, presently known as main memory or simply RAM (Random Access Memory), is the only one directly accessible to the CPU. The CPU continuously reads instructions stored there and executes them as required. Any data actively operated on is also stored there in uniform manner.

Memory stores three basic categories of data.

1. Operating system and other system software that control or maintain the computer and its devices
2. Application programs that carry out a specific task such as word processing etc.
3. Data to be processed by the application programs and resulting information.

 RAM varies in size like 128 MB, 256 MB, 512 MB to 4 GB.  RAM can not store data and instruction permanently. When we switch off the computer, all data and instructions from RAM are washed or vanished. Therefore it is called volatile memory.