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Asked: 2026-05-25T21:32:00+00:00

I was recently asked a question that in a computer system, if the primary

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I was recently asked a question that in a computer system, if the primary memory(RAM) is comparable to the secondary memory (HDD) then is there a need for virtual memory to be implemented in such a computer system ?
Since paging and segmentation require context switching, which is purely processing overhead, would the benefits of virtual memory overshoot the processing overhead it requires ?
Can someone help me with this question ?
Thanku

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1 Answer

  1. Editorial Team

    I’m going to dump my understanding of this matter, with absolutely no background credentials to back it up. Gonna get downvoted? 🙂

    First up, by saying primary memory is comparable to secondary memory, I assume you mean in terms of space. (Afterall, accessing RAM is faster than accessing storage).

    Now, as I understand it,

    Random Access Memory is limited by Address Space, which is the addresses which the operating system can store stuff in. A 32bit operating system is limited to roughly 4gb of RAM, while 64bit operating systems are (theoretically) limited to 2.3EXABYTES of RAM, although Windows 7 limits it to 200gb for Ultimate edition, and 2tb for Server 2008.

    Of course, there are still multiple factors, such as

    • cost to manufacture RAM. (8gb on a single ram thingie(?) still in the hundreds)

    • dimm slots on motherboards (I’ve seen boards with 4 slots)

    But for the purpose of this discussion let us ignore these limitations, and talk just about space.

    Let us talk about how applications nowadays deal with memory. Applications do not know how much memory exists – for the most part, it simply requisitions it from the operating system. The operating system is the one responsible for managing which address spaces have been allocated to each application that is running. If it does not have enough, well, bad things happen.

    But, surely with theoretical 2EXABYTES of RAM, you’d never run out?

    Well, a famous person long ago once said we’d never need more than 64kBs of RAM.

    Because most Applications nowadays are greedy (they take as much as the operating system is willing to give), if you ran enough applications, on a powerful enough computer, you could theoretically exceed the storage limits of the physical memory. In that case, Virtual Memory would be required to make up the extra required memory.

    So to answer your question: (in my humble opinion formed from limited knowledge on the matter,) yes you’d still need to implement virtual memory.

    Obviously take all this and do your own research. I’m turning this into a community wiki so others can edit it or just delete it if it is plain wrong 🙂

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