Posted by : Ali Khan Sunday, 7 July 2013

“Virtual Memory is an extremely large main memory than physical memory”. Do you agree with the given statement or not? Give reason to support your answer.

Solution: 
Yes , I agree Virtual Memory is an extremely large main memory than physical memory”
.Physical memory is the memory on the RAM Chips in your computer. This memory can be added or removed, and works very fast. The problem is that it’s finite: once you run out, you run out. 
Virtual memory is the hard disk being used in the same manner as physical memory. Virtual memory can be as large as the remaining available free hard drive space on your PC, but it’s much slower to access and not as useful as your physical memory.
The main idea is that if a virtual address is not mapped into the physical memory, then it has to be fetched from the disk. The unit of transfer is a page (or a segment). Observe the similarities (as well as differences) between virtual memory and cache memory. Also, recall how slow is the disk (~ ms) to the main memory (50 ns). So each miss (called a page fault or a segment fault) has a large penalty.

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