# Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 19 (Page No. 256)

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A computer with a $32-bit$ address uses a two-level page table. Virtual addresses are split into a $9-bit$ top-level page table field, an $11-bit$ second-level page table field, and an offset. How large are the pages and how many are there in the address space?

$\underline{\mathbf {Answer:}}$

Number of bits used for virtual page numbers $=20$

Number of bits used for offset $=12$

$\therefore$ Size of Page $=\;\mathbf{4K} \;$.

$20$ bits for Virtual Page means $2^{20}$ pages.

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can you plz explain the meaning of “how many are there in the address space”

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