GATE 2025 CS (CS2) – Question 58
A computer system supports a logical address space of $2^{32}$ bytes. It uses two-level hierarchical paging with a page size of 4096 bytes. A logical address is divided into a $b$-bit index to the outer page table, an offset within the page of the inner page table, and an offset within the desired page. Each entry of the inner page table uses eight bytes. All the pages in the system have the same size.
The value of $b$ is ___________ . (Answer in integer)
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Correct answer: 11
Explanation
The page offset is 12 bits. An inner page table page holds 4096/8 = 512 entries, so the inner index is 9 bits. Therefore $b = 32 - 12 - 9 = 11$.