Patent ID: 6958881

Claim:
A magnetic disk drive, comprising: a head disk assembly (HDA) including a rotating magnetic disk having distributed position information in a plurality of uniformly spaced-apart servo wedges for defining data storage tracks, an actuator for positioning a transducer head in response to a control effort signal, the transducer head for periodically reading the distributed position information from the servo wedges and reading data from the data storage tracks; and a control system having an accelerator circuit for implementing a first sampled servo controller for periodically adjusting, only during a track-following operation under one or more of a first set of predetermined conditions, the control effort signal based on the distributed position information, and for indicating the occurrence of a predetermined condition within a second set of predetermined conditions to the control system; a second sampled servo controller, separate from the accelerator circuit, for periodically adjusting the control effort signal based on the distributed position information during a track-following operation under one or more of the second set of predetermined conditions.