August
1999 QUESTION 4 Total Marks: 20 Marks |
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| An important feature
in designing a system is the construction of its memory hierarchy.
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| (a) | Draw a diagram showing the main elements of
the memory hierarchy and showing with arrows how the size, cost and access time vary for
the different forms of memory.
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| (b) | What is the purpose of virtual memory? Will
the virtual memory address space be larger or smaller than the physical memory address
space? Explain your answer.
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| (c) | In virtual memory, what is the page table?
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| (d) | Using the page table can mean that each memory
access takes twice as long as it would without virtual memory. Explain why this is, and
how a translation lookaside buffer (TLB) may be used to overcome this difficulty.
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| (e) | In which ways are virtual memory and the cache
similiar? What are the main differences?
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