| 摘要 |
PURPOSE:To make high-speed access possible in the case of defective track information by storing defective track information and alternative track information and providing a discriminating device which outputs alternative track information when defective track information is obtained. CONSTITUTION:A defective track discriminating device 6 discriminates whether given track information is defective track information or not. Track information is given to a head moving controller 3 as it is if it is normal track information; but it is defective track information, alternative track information corresponding to this defective track information is given to the head moving controller 3. The head moving controller 3 moves the head of a head and disc device 5 on the basis of given track information. In this head position, a disc controller 1 can read out data immediately. Since the track discriminating device which outputs alternative track information as head moving information is provided in this manner, a very high-speed access is possible in the case of defective track information. |
