Question-1 What is Virtual Memory? Explain in brief.
- The basic idea behind virtual memory is that each program has its own address space, which is broken up into pages.
- Each page is a contiguous range of addresses.
- These pages are mapped onto the physical memory but, to run the program, all pages are not required to be present in the physical memory.
- The operating system keeps those parts of the program currently in use in main memory, and the rest on the disk.
- Virtual memory works fine in a multiprogramming system, with bits and pieces of many programs in memory at once.
- While a program is waiting for part of itself to be brought in, it is waiting for I/O and cannot run, so the CPU can be given to another process.
- In a system using virtual memory, the physical memory is divided into page frames and the virtual address space is divided in into equally-sized partitions called pages.