Any location in the main memory is uniquely identified by an address. This address is called the physical address of the main memory (RAM).
The address that CPU Is called a logical address.
The group of all logical addresses in the main memory is called logical address space.
A group of all physical address is called physical address space.
These logical addresses are converted into a physical address and the process in which the logical address is converted to physical address is called memory mapping.
The hardware unit that changes the logical address to physical address is called a memory management unit (MMU).
There are many methods of memory mapping, but the simplest method is using the relocation register for memory mapping. In this, the base address of the program is loaded in the relocation register. The physical address is calculated by adding value to the relocation register in the logical address.
For example – The base address of the program is 39000 if the logical address in the program is 338 then the logical address is added to the base address then the physical address 39338 is generated.