Write precompensation
Encyclopedia
Write precompensation is a technical aspect of hard disk
design. It is the use of a stronger magnetic field
to write data
in sector
s that are closer to the center of the disk. In constant angular velocity recording, in which the disk spins at a constant speed no matter where the data is written, the sectors closest to the spindle are packed tighter than the outer sectors and so require a stronger magnetic field to write the data.
In the past one of the hard disk parameters stored in a PC's CMOS memory is the WPcom number, a marker of the track where precompensation begins. Modern hard disks rarely access the CMOS memory and internally store the WPcom number if write precompensation is used.
Hard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...
design. It is the use of a stronger magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
to write data
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
in sector
Disk sector
In computer disk storage, a sector is a subdivision of a track on a magnetic disk or optical disc. Each sector stores a fixed amount of user data. Traditional formatting of these storage media provides space for 512 bytes or 2048 bytes of user-accessible data per sector...
s that are closer to the center of the disk. In constant angular velocity recording, in which the disk spins at a constant speed no matter where the data is written, the sectors closest to the spindle are packed tighter than the outer sectors and so require a stronger magnetic field to write the data.
In the past one of the hard disk parameters stored in a PC's CMOS memory is the WPcom number, a marker of the track where precompensation begins. Modern hard disks rarely access the CMOS memory and internally store the WPcom number if write precompensation is used.