The present invention relates to a magnetic disk drive apparatus or system, and more particularly to an actuator driving method which is well suited to a magnetic disk drive apparatus having a large number of actuators or a magentic disk drive system including a large number of HDA's (Head Disk Assemblies).
As an invention pertinent to a method of driving a large number of actuators, Japanese Patent Application Laid-open No. 55-12528 discloses a method which shares a coarse servo circuit for a plurality of actuators carried on a disk drive apparatus, thereby intending to attain reduction in cost. With this method, however, the lowering of throughput occurs due to the fact that the plurality of actuators cannot be simultaneously accessed. Another problem is that, since an expensive, high power amplifier for a high speed access control is shared in a track following positioning control, the cost rises.