Source : Free On-Line Dictionary of Computing

Logical Block Addressing
     
         (LBA) A {hard disk} {sector} addressing scheme used
        on all {SCSI} hard disks, and on {ATA-2} conforming {IDE} hard
        disks.  The addressing conversion is performed by the hard
        disk firmware.
     
        Prior to LBA, combined limitations of {IBM PC} {BIOS} and
        {ATA} restricted the useful capacity of IDE hard disks on IBM
        PCs and compatibles to 1024 cylinders * 63 sectors per track *
        16 heads * 512 bytes per sector = 528 million bytes = 504
        megabytes.  Modern BIOSes select LBA mode automatically, and
        work around the 1024-cylinder BIOS limit by representing a
        hard disk to the OS as having e.g. half as many cylinders and
        twice as many heads.  However, there is still an unbreakable
        BIOS disk size limit of 1024 cylinders * 63 sectors per track
        * 256 heads * 512 bytes per sector = 8 gigabytes, but modern
        OSes (including {Windows 9x}, {Windows NT} and {Linux}) are
        not affected by it, since they issue direct LBA-based calls,
        bypassing the BIOS hard disk services completely.
     
        (2000-04-30)