| 摘要 |
PURPOSE: To effectively prevent unauthorized copying without affecting ordinary operation. CONSTITUTION: A security track 14 on a disk 10 is formed as a spiral different from the spiral of data tracks 12. Even if, therefore, the data is wholly copied on another disk by continuously reproducing the data tracks 12, the copying of the data of the security track 14 is infeasible. Only the data tracks 12 are accessed and the security track 14 is not accessed at the time of ordinary reproduction and, therefore, such trouble as occurrence of a tracking error by a protect code does not arise. |
