| 摘要 |
PURPOSE:To prevent destruction of data which is written in a magnetic disk device and should be protected by inhibiting the write to only an arbitrary area of the magnetic disk device where normal data is written. CONSTITUTION:A magnetic disk controller consists of a data transfer circuit 110, a storage circuit 120, and a microprogram control circuit 130. When the indication of data write to an arbitrary cylinder number is received from a central processing unit after a first cylinder number and a last cylinder number which indicate the write inhibit area of the magnetic disk device sent from the central processing unit are stored in the storage circuit 120, it is informed the central processing unit that the indication of write to the write inhibit area is sent from the central processing unit if the arbitrary cylinder number is in the write inhibit area. Thus, destruction of data to be protected is prevented though the indication of write to a data protection area in the magnetic disk device is erroneously sent because of trouble. |
