Patent ID: 7130142

Claim:
A magnetic disk apparatus comprising: a head that reads and writes data from and on a magnetic disk; a servo-information detecting unit that detects a present head position from a signal supplied from the head; a write-permission determining unit that calculates a present head speed and a present head acceleration from the present head position and a previous head position detected in the past, and determines whether data can be written, from the present head position, a present head speed and a present head acceleration; a data-writing unit that writes data in accordance with a decision made by the write-permission determining unit; and a head-driving unit that drives the head in accordance with the present head position, wherein the write-permission determining unit calculates the present head speed and the present head acceleration from the present head position, the last head position and the penultimate head position factors in the present head position, present head speed and present head acceleration, thereby inferring a next head position, determines that data-writing is permitted, when the present head position and the next head position fall within a predetermined write-prohibiting slice, and determines that the data-writing is prohibited, when the present head position and the next head position fall outside the predetermined write-prohibiting slice.