| 摘要 |
PURPOSE:To protect information peculiar to a magnetic disk which is required at the time of maintaining, by adding a prescribed value to an address which is sent out to the magnetic disk when an instruction opened to a general user arrives, so that a general use cannot use an address area being below its prescribed value. CONSTITUTION:First of all, an instruction procedure to a magnetic disk controlling circuit 8 by decoding an instruction from a host device 2. Subsequently, whether its instruction is an instruction (maintenance use command) which is not opened to a general use or not is decided, and when it is not the maintenance use command, an address of a magnetic disk 3, instructed to the magnetic disk controlling circuit 8 is set to a value which has added '1' to an address received from the host device 2. Next, a seek start for moving a cylinder of the magnetic disk 3 is outputted to the magnetic disk controlling circuit 8, and the magnetic disk controlling circuit 8 receives it and outputs a head moving signal by a necessary portion to the magnetic disk 3. In such a way, by only adding a simple processing, a specific area of the magnetic disk 3 cannot be brought to an access by general use, and information peculiar to the magnetic disk, which has been stored therein can be protected. |
