, short for Write
Precompensation, is a technique
used on hard drive
s for changing the timing of data
that is written to disk, depending on the current cylinder
Because the tracks towards the center of the spinning disk are shorter than those on the outer edge, the manufacturers need to compensate for the read timing differences. They came up with altering the timing of the writing procedure for the cylinders closest to the hub.
Old hard drives do not have on-board logic to control the write precomp, so one had to enter it manually in the computer's BIOS settings. Modern drives have the logic incorporated in the drive electronics to perform the write precomp transparent to the end user.