Main-Memory Management

Primary-Memory or Main-Memory is a large array of words or bytes. Each word or byte has its own address. Main-memory provides storage that can be access directly by the CPU. That is to say for a program to be executed, it must in the main memory.
The major activities of an operating in regard to memory-management are:
Keep track of which part of memory are currently being used and by whom.
Decide which process are loaded into memory when memory space becomes available.
Allocate and deallocate memory space as needed.