GATE 2017 CS (CS2) – Question 63

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

A byte-addressable main memory has 2³² bytes, divided into 32-byte blocks. A direct-mapped cache has 512 lines. Find tag-field size in bits.

Show answer and explanation

Correct answer: 18.0 to 18.0

Explanation

The address is 32 bits. Block offset uses log₂32=5 bits; cache-line index uses log₂512=9 bits. The remaining 32−5−9=18 bits identify the memory tag.

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