Consider a disk pack with 32 surfaces, 64 tracks and 512 sectors per pack. 256…
2018
Consider a disk pack with 32 surfaces, 64 tracks and 512 sectors per pack. 256 bytes of data are stored in a bit serial manner in a sector. The number of bits required to specify a particular sector in the disk is
- A.
18
- B.
19
- C.
20
- D.
22
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Correct answer: C
Key insight: the number of bits needed equals log2(total number of sectors).
Compute total sectors: 32 surfaces × 64 tracks × 512 sectors = 1,048,576 sectors.
Express as a power of two: 1,048,576 = 2^20.
Therefore the number of bits required to uniquely specify a sector is 20.
Note: The given 256 bytes per sector would only matter if the question asked to address a specific bit within a sector. In that case you would add log2(256 × 8) = log2(2048) = 11 bits for intra-sector bit addressing; but for sector addressing alone, 20 bits suffice.
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