Virtual memory is an old concept; before computers had caches, they had virtual

Question

Virtual memory is an old concept; before computers had caches, they had virtual memory. For a long time, virtual memory only appeared on mainframes. Personal computers in the 1980s did not use virtual memory. In fact, many good ideas that were in common use in the UNIX operating systems didn't appear in personal computer operating systems until the mid-1990s.

Initially, virtual memory meant the idea of using disk to extend RAM. Programs wouldn't have to care whether the memory was "real" memory (i.e., RAM) or disk. Later on, virtual memory was used as a means of memory protection. Every program uses a range of addresses called the address space.

Discuss the advantages of virtual memory. Identify some real-life applications of virtual memory and discuss why virtual memory would be beneficial in those situations.

Explanation / Answer

Virtual memory basically involves a computer to compensate for shortages of physical memory by temporarily transferring pages of data from random access memory (RAM) to disk storage.This has following advantages:

1..Multiple applications can run simultaneously.

2.This helps to eliminate external fragmentation.

3.It results in more efficient swapping-the operating system has the abilty move other pages to hard disk so it has room to bring back the pages it needs right away from temporary disk storage. This process is known as paging or swapping

4.Allocating the memory is easy and cheap and can be done depending on the size of the process rather than predeclaring it is static in case of arrays.

5. It provides the ability to load and execute a process that requires a larger amount of memory than what is available by loading the process in parts and then executing them.

6.It allows demand paging and prepaging

Real time application of virtual application involves

to remember the birthdays of 50 friends .we can write them down on a sheet of paper(virual memory).then we can sort them out monthly that will be around 50/12=4 birthdays per month.now we need to remmber just 4 dates per month in the memory and then we can use the virtual memory from the sheet of paper to know whose birthday it is as and when it is required .This is how virtual memory works.

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