As discussed in the section on zoned bit
recording, older hard disks used the same number of sectors per track. This meant that
older disks had a varying bit density as you moved from the outside edge to the inner part
of the platter. Many of these older disks required that an adjustment be made when writing
the inside tracks, and a setting was placed in the BIOS to allow the user to specify at
what track number this compensation was to begin.
This entire matter is no longer relevant to modern hard disks, but the BIOS setting remains for compatibility
reasons. Write precompensation is not done with today's drives; even if it were, the
function would be implemented within the integrated controller and would be transparent to
the user.
Next: Interleaving
