The GATE Grind

GATE 2021 CS – Question 32

Computer Organization and Architecture · Memory Interfacing and Hierarchy · 1 mark · Numerical answer

Consider a computer system with a byte-addressable primary memory of size $2^{32}$ bytes. Assume the computer system has a direct-mapped cache of size 32 KB (1 KB = $2^{10}$ bytes), and each cache block is of size 64 bytes. The size of the tag field is ______ bits.

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Correct answer: 17

Explanation

Offset = 6 bits. Blocks = 32KB/64B = 512, so index = 9 bits. Tag = 32 - 9 - 6 = 17 bits.