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In computer disk storage, a sector is a subdivision of a track on a magnetic disk or optical disc. For most disks, each sector stores a fixed amount of user-accessible data, traditionally 512 bytes for hard disk drives (HDDs), and 2048 bytes for CD-ROMs, DVD-ROMs and BD-ROMs. [1]
Many host computer hardware and software components assume the hard drive is configured around 512-byte sector boundaries. This includes a broad range of items including chipsets, operating systems, database engines, hard drive partitioning and imaging tools, backup and file system utilities as well as a small fraction of other software applications.
Floppy disks and controllers had used physical sector sizes of 128, 256, 512 and 1024 bytes (e.g., PC/AX), but formats with 512 bytes per physical sector became dominant in the 1980s. [ 3 ] [ 4 ] The most common physical sector size for hard disks today is 512 bytes, but there have been hard disks with 520 bytes per sector as well for non-IBM ...
With the standard hard disk sector size of 512 bytes, this gives a maximum of 32 KB cluster size, thereby fixing the "definitive" limit for the FAT16 partition size at 2 GB for sector size 512. On magneto-optical media, which can have 1 or 2 KB sectors instead of 0.5 KB, this size limit is proportionally larger.
Under the assumption that the drive in question reports a sector size of 512 bytes, then dividing this byte offset by 512 results in 63, which is the physical sector number (or LBA) containing the first sector of the partition (unlike the sector count used in the sectors value of CHS tuples, which counts from one, the absolute or LBA sector ...
The drive had 35 tracks and was single sided. The data sheet gives the unformatted capacity as 3125 bytes per track for a total of 109.4 K bytes (3125 × 35 = 109 375). When formatted with 256 byte sectors and 10 sectors per track the capacity is 89.6 K bytes (256 × 10 × 35 = 89 600). [69]
1 byte: A number from 0 to 255; 90 bytes: Enough to store a typical line of text from a book; 512 bytes = 0.5 KiB: The typical sector size of an old style hard disk drive (modern Advanced Format sectors are 4096 bytes). 1024 bytes = 1 KiB: A block size in some older UNIX filesystems; 2048 bytes = 2 KiB: A CD-ROM sector
The second property requires dividing the disk into several sectors, usually 512 bytes (4096 bits) long, which are encrypted and decrypted independently of each other. In turn, if the data is to stay confidential, the encryption method must be tweakable ; no two sectors should be processed in exactly the same way.