Memory management in an operating system is all about handling how memory is used and shared between different programs. The goal is to make sure that memory is used efficiently, safely, and that multiple programs can run smoothly without crashing into each other.
In a computer running multiple programs, we don’t know where each program will be placed in memory beforehand. The operating system might move programs around to free up space or load new ones. But even if a program gets moved, it still needs to work properly.
Branch instructions contain an address to reference the instruction to be executed next.
Data reference instructions contain the address of the byte or word of data referenced.
So, memory management ensures that the program’s references to memory addresses get updated when it is relocated.
Programs should be isolated from each other, so one program cannot accidentally or maliciously access or modify another program’s memory.
For example, if you’re using a word processor, it shouldn’t be able to mess with your browser’s memory.
The system checks every memory access request at run-time to make sure that programs stay in their own memory space.
Sometimes, multiple programs might need to use the same data or code.
For example, many programs may run the same piece of code like a library or system function.
Instead of loading multiple copies of the same data or code into memory, memory management allows them to share memory safely, without breaking protection rules.
Main memory in a computer system is organized as a linear, or one-dimensional, address space, consisting of a sequence of bytes or words.
Programs are often broken up into pieces or modules (like the code section, data section, etc.).