| 摘要 |
<p>PURPOSE:To prevent the infringement of copyright by realizing the protection of a program verifying mode of an action mode decoder. CONSTITUTION:A signal T is produced by an exclusive OR circuit 14, an AND circuit 16, etc., and set at H only when the coincidence is secured between the data on a data latch circuit group 13I and that on a data latch circuit group 13II. Then the signal T and the output Ve' obtained via an AND secured with the output Ve of an action mode selecting decoder 11 are used as the verifying signals of an EPROM. This program verifying signal Ve' is set at H only when the coincidence is obtained between both circuits 13I and 13II. Thus a program verifying action can be protected. Therefore a person who does not know a due password is unable to check the program contents via an EPROM writer or to copy the program contents. As a result, the copyright of a program is easily protected.</p> |
