Discussion
An application has to modify 34th byte in sector number 4 (on first track present on first side of the first plate) on a conventional hard disk. Operating system will copy how many bytes from that sector into primary memory to enable this operation to be performed ?
Answer: D
The operating system copies 512 bytes.
A disk cannot read or write a single byte. The smallest unit it transfers is a sector, which on a conventional hard disk holds 512 bytes. To change the 34th byte, the operating system reads the whole sector into a buffer in main memory, changes that byte, and writes the whole sector back.
1 and 34 assume byte-level access, which disks do not offer, and 136 (34 × 4) mixes the byte number with the sector number.
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