GATE 2023 CS – Question 64

Computer Organization and Architecture · Memory Interfacing and Hierarchy · 2 marks · Numerical answer

An 8-way set associative cache of size 64 KB (1 KB = 1024 bytes) is used in a system with 32-bit address. The address is sub-divided into TAG, INDEX, and BLOCK OFFSET. The number of bits in the TAG is ______.

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Correct answer: 19

Explanation

Index bits + offset bits = log₂(cache size / associativity) = log₂(64K/8) = 13, regardless of block size. So TAG = 32 − 13 = 19 bits.