Abstract: A magnetic disk apparatus includes a reproducing circuit for reproducing a signal recorded in a medium, a reproduced signal processing controller having a TA compensation mode to effectively control reproduced signal processing in accordance with generation of TA, a reproduced signal processor for processing the reproduced signal output from the reproducing circuit under the control of the reproduced signal processing controller, and an HDC.

Abstract: At a predetermined time before activation of a motor of a hard disk drive HDD, a central processing unit CPU transfers a part of a speed control routine or a part of a position control routine from a read only memory ROM via an external bus, and stores the transferred part in a command random access memory RAM. When a servo process is executed, the CPU accesses to the ROM and the command RAM and executes a head positioning control consisting of a speed control and a position control. Thereby, a routine stored in the command RAM can be accessed at high speed. As a result, a servo process time period can be reduced.

Abstract: In the head positioning control system in the magnetic disk device of the index servo system of the invention, a position signal representing the position of the head on the disk, generated by a position signal generator, is converted by an A/D converter into a digital signal. Based on the digital signal, a CPU determines positioning correction data. The CPU stores positioning correction data in a memory, converts it into an analog signal by a D/A converter, and drives a stepping motor through a distributor and a magnetizing circuit so as to correct the position of the magnetic head.