Logical Address - Computer Memory

Computer Memory

The physical address of computer memory banks may be mapped to different logical addresses for various purposes.

For example, the same physical memory may appear at two different logical addresses and if accessed by the program at one address, data will pass through the CPU cache whereas if it is accessed at the other address, it will bypass the cache.

In a system supporting virtual memory, there may actually not be any physical memory mapped to a logical address until an access is attempted. The access triggers special functions of the operating system which reprogram the MMU to map the address to some physical memory, perhaps writing the old contents of that memory to disk and reading back from disk what the memory should contain at the new logical address. In this case, the logical address may be referred to as a $ virtual address.