File Management

Memory Management

POS/355 Introduction to Operating Systems

Memory management is a critically important aspect of any operating system which, when utilized correctly, can distribute portions of memory to programs and software after freeing space in the computer memory. Without memory management a computer will not run efficiently as there will not be a supply of ready processes to utilize available processor time (Stallings, 2015).

There are several requirements that memory management seeks to fulfill: relocation, protection, sharing, logical organization, and physical organization. Since the computer must allow for the possibility that a program may be moved within the main memory, relocation allows the computer to translate a reference found in the code of the program into a physical memory that shows its present location in the main memory. Since the programmer will not know at the time of program execution which other programs are stored in the main memory, and in order to free up the process of swapping the program back into the main memory, relocation is utilized. Protection deals with interference by other processes, disallowing other processes from referencing memory locations for reading or writing purposes, unless permission is given within the process. Made more difficult by the relocation requirement, the protection requirement is satisfied by the processor, not the operating system, due to the fact that the operating system cannot predict the memory references any given program will make. Occasionally, several processes will need to access the same portion of the main memory while cooperating on a task. Sharing allows multiple processes to do so in a controlled method without compromising protections.

Logical organization of memory allows modules to be compiled and written independently, it allows for different protections such as read only or execute only to be given to different modules, and allows modules to be shared among...