38. Why is memory management necessary in a system that uses hard disks?

What will be an ideal response?

Without memory management, all logical addresses from the processor would be mapped onto the same
physical addresses in memory. Memory management makes it possible to map any logical address space onto
any physical address space, making it easy to provide memory space protection and shared data or program
space (for example, two different tasks could share the same library of functions).
However, the main use of memory management is to integrate the disk space into memory space. This allows
gigantic memory spaces. Suppose the logical address space is very much larger than the physical address space
of the DRAM. If a logical address is generated and the corresponding data is on disk, the operating system can
read the disk and transfer a page into DRAM and then map that page onto the logical address space. As long as
pages are not swapped in too frequently, memory management can effectively hide a hard disk’s latency.