Q1. Explain Virtual Memory.
Ans. Virtual memory is a computer system technique which gives an application program the impression that it has contiguous working memory, while in fact it may be physically fragmented and may even overflow on to disk storage.
The basic idea behind virtual memory is that the combined size of the program, data and stack may exceed the amount of physical memory available for it. The operating system keeps those parts of the program currently use in main memory and the rest on the disk.
A 16 MB program can run on a 4 MB machine by carefully choosing which 4 MB to keep in main memory at each instance, with pieces of the program being swapped between disk and memory as needed.