A CPU generates 32 bits virtual addresses. The page size is 4 KB. The processor has a translation look-aside buffer (TLB) which can hold a total of 128-page table entries and is 4 way set associate. The minimum size of the TLB tag is
- A. 11 bits
- B. 15 bits
- C. 13 bits
- D. 20 bits
✅ Correct Answer: 15 bits
Explanation
Total virtual address space is $2^{32}$. Page size is $4\,KB = 2^{12}$. Total pages $= 2^{32} / 2^{12} = 2^{20}$. TLB entries $= 128 = 2^7$. 4-way set associative means number of sets $= 2^7 / 2^2 = 2^5$. Tag size $= 20 - 5 = 15$ bits.
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