| 摘要 |
PURPOSE:To hold the secrecy of a program by constituting the titled computer so that an input of a key word and a comparison of the key word and a ROM data are repeated by a prescribed number of times, and thee contents of a program store use P-ROM cannot be read out to the outside when there is no coincidence during that time. CONSTITUTION:At the time of reading out the contents of a P-ROM 5, a key word from the outside is divided into several times by a one step portion each and inputted from an input part 1. Subsequently, the inputted key word and the contents of a specific address of the P-ROM 5 are compared by a comparing part 2. In case the coincidence cannot be obtained by a result of comparison, the number of times of discrepancy is counted, a count value of a data coincidence frequency counter 3 is added by '1', and an output part 4 is set to a disenable state so that the contents of the P-ROM 5 cannot be read out to the outside. In this case, a key word input by the input part 1, and a key word comparing work which follows up said input are repeated. In such a way, the secrecy of a program being the contents of the P-ROM can be held. |
