| 摘要 |
PROBLEM TO BE SOLVED: To prevent the copying of optical disk by an illegal copying of data on a program recorded in an optical disk while satisfying a disk specification. SOLUTION: A reproduction pickup unit 2 accesses a sub-channel in the read in area of a CD-ROM disk 1 and reads the first key code of a table of contents(TOC) area. The reproduction pickup unit 2 accesses the main channel of a read out area and reads a second key code. A control microcomputer 6 judges the presence or absence of the first and second key codes. When at least one of the first and second key codes is not detected, the control microcomputer 6 controls the reproduction pickup unit 2 not to execute a reproduction operation. |
