A processor can support a maximum memory of 4 GB where memory is word…

2019

A processor can support a maximum memory of 4 GB where memory is word addressable and a word is 2 bytes. What will be the size of the address bus of the processor?

  1. A.

    At least 28 bits

  2. B.

    At least 2 bytes

  3. C.

    At least 31 bits

  4. D.

    Minimum 4 bytes

Attempted by 604 students.

Show answer & explanation

Correct answer: C

Approach: Find the number of addressable words, then take log base 2 to get the required number of address lines.

  • Total memory = 4 GB = 2^32 bytes.

  • Word size = 2 bytes, so number of addressable words = 2^32 / 2 = 2^31.

  • Number of address lines required = log2(number of words) = log2(2^31) = 31 bits.

Conclusion: The address bus must be 31 bits (so at least 31 bits).

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