When writing to a disk, some or all tracks can have write precompensation applied. This technique compensates for the tendency for consecutive flux transitions to interact and cause them to spread apart. The effect is particularly noticeable on inner tracks where the bit density is highest.

The precomp specifier is presented by --precomp= and can contain any of the following elements:

• type=<t>: Precomp type (mfm, fm, gcr): Default mfm
• <c>=<p>: Precompensate all cylinders >= c by p nanoseconds.

For example:

• 40=125: Apply 125ns MFM precompensation to cylinders 40 and higher