Requirements of Memory Management

Logical Organisation:

Although processes in memory often occupy linear sequences of addresses, programs are seldom written, or execute, this way.

Structured programming and, more recently, object-oriented techniques, encourage/enforce programming using modules which are developed and compiled independently.

Ideally, all references from one module to another are resolved at run-time, maintaining their independence (termed late binding).

Physical Organisation:

The relationship between primary memory (RAM) and secondary memory (disk) is straightforward, but not one that programmers wish to manage. Old techniques termed overlays permitted reuse of a process's memory, but (today) are unnecessarily complex.

Moreover, in a multi-programmed system, the programmer cannot predict the size nor location of a process's memory. The task of moving information between main and secondary memory is clearly the responsibility of the operating system.