UGC NET CSE | December 2018 | Part 2 | Question: 18

Question

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. $22$

Comments

But it is mentioned 512 sectors per pack.

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yes printing mistake most probably :/

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Thanks

Answer 1

32 surfaces = 5 bits, 64 tracks = 6 bits, 512 sectors = 9 bits, sector size 256 bytes =8 bits
To specify a particular sector, we do not need sector size, so bits required $=5+6+9=20$ bits.

Answer 2

To calculates the number of bits required to access  sector we need to know total number of sector

Total number of sector =32 Surface * 64 Tracks * 512 Sector

                                     = 2^5 * 2^6  * 2^9

                                     =  2^20

No. of bits required to identify each sector=20 bits

So option 2 is correct  answer.