Chapter 9: Main Memory: Paging, Allocation, and Swapping

Main Memory: Paging, Allocation, and Swapping begins with a discussion of basic hardware concepts, including address binding, logical versus physical addresses, and the role of the memory management unit (MMU). The chapter then covers the process of loading programs into memory, from compile time to execution time, and explains dynamic loading and linking. Contiguous memory allocation methods are introduced, including fixed and variable partitioning, along with problems like external and internal fragmentation. Swapping techniques are detailed, showing how processes are temporarily moved between main memory and backing storage. The chapter explores non-contiguous memory allocation via paging, detailing page tables, page sizes, and frame allocation, as well as hierarchical, hashed, and inverted page tables. Segmentation is also presented as an alternative that supports modular program design. The trade-offs between paging and segmentation are discussed, including complexity, flexibility, and performance implications. Real-world memory management strategies from systems such as Windows and Linux are examined to show how these concepts are implemented in practice. By the end, readers understand how operating systems allocate, track, and protect main memory to ensure efficient and reliable execution of processes.