Data and instructions are stored in the Main Memory.
It stores programs and data when the computer is running. Programs that are to be executed by the computer are placed in the main memory and the CPU in turn gets each instruction from the memory and executes it. Main memory is fast and limited in its capacity. Only the CPU can access the information in main memory directly. The main memory cannot retain information when the computer is switched off. Main memory has a series of locations that are called bytes, each byte equals eight bits. Every byte has an address related to it by which it can be accessed. The address is stored in the form of a number.
For example, you would find the mail for James by looking in James' letterbox.
In the same way, the control unit will find the contents of location 1 by
looking in that location.
