| 摘要 |
PURPOSE:To protect programs with a simple constitution by using a cylinder key to set the levels of loadable programs and loading these programs after discriminating whether the level of the program received a start request is higher or lower than a set level. CONSTITUTION:A cylinder key 1 is used to set the level of a startable program and has the limited one of rotary angles L1-Ln according to the type of a keyhole 1-2 of a lock 1-1. These angles L1-Ln are detected by a multi-step contact provided to the lock 1-1. For instance, the key 1 can turn up to the position L1 and a key 2 can turn up to the position L2 and so on. Thus the used key can be specified by detecting the angles which are turned by keys 1-n according to a opened or closed state of said multi-step contact. |
