| 摘要 |
PURPOSE:To completely prevent a program from being run illegally apart from an executable period by generating an interruption signal that cannot be masked if a decoded executable period excludes the current time. CONSTITUTION:Prior to the execution of a program, an encoded executable period code recorded in the program is inputted and decoded in a decoder 11, and stored in a register 12. On the other hand, a timing device 12 transmits time to a comparator 14 without fail. The comparator 14 compares the time with the executable period stored in the register 12. If the time is included in the executable period, an interruption generation circuit 15 never generates an interruption signal. If not, the circuit 15 generates the interruption signal that cannot be masked to a computer. Accordingly the program concerned can be run only during the executable period which is encoded and recorded in the program. |
