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In logical block addressing, only one number is used to address data, and each linear base address describes a single block. The LBA scheme replaces earlier schemes which exposed the physical details of the storage device to the software of the operating system. Chief among these was the cylinder-head-sector (CHS) scheme, where blocks were addressed by means
INT 13h is shorthand for BIOS interrupt call 13 hex, the 20th interrupt vector in an x86-based (IBM PC-descended) computer system.The BIOS typically sets up a real mode interrupt handler at this vector that provides sector-based hard disk and floppy disk read and write services using cylinder-head-sector (CHS) addressing.
The term fixed-block architecture was created by IBM in 1979 [3] to distinguish this format from its variable-length record format. Each track is divided into fixed-length blocks, consisting of an ID field and a data field. Application programs refer to blocks by relative block number, and cannot address them by cylinder, head and record.
A "direct access" (i.e. disk type) storage device consists of a number of logical blocks, addressed by Logical Block Address . A typical LBA equates to 512 bytes of storage. The usage of LBAs has evolved over time and so four different command variants are provided for reading and writing data.
Like MBR, GPT uses logical block addressing (LBA) in place of the historical cylinder-head-sector (CHS) addressing. The protective MBR is stored at LBA 0, and the GPT header is in LBA 1, with a backup GPT header stored at the final LBA. The GPT header has a pointer to the partition table (Partition Entry Array), which is typically at LBA 2 ...
Logical block addressing (LBA) is supported in MS-DOS 7 for accessing larger hard disks, unlike earlier versions which only supported cylinder-head-sector (CHS)-based addressing. Unlike MS-DOS 7.0, MS-DOS 7.1 recognizes a hard disk beyond the first 8.4GB. [14] Year 2000 support was added to DIR command via the new /4 option.
In 1996, support for logical block addressing (LBA) was introduced in Windows 95B and MS-DOS 7.10 (Not to be confused with IBM PC-DOS 7.1) in order to support disks larger than 8 GB. Disk timestamps were also introduced. [2] This also reflected the idea that the MBR is meant to be operating system and file system independent.
CLI—Command line interface; ... JFS—IBM Journaling File System; ... LBA—Logical Block Addressing; LB—Load Balancer;