| 摘要 |
PURPOSE:To protect the secrecy of a software program by supplying the output data of a program memory and the output data of an optional number counter to an arithmetic circuit at application of a prescribed external control signal and outputting the arithmetic result of the arithmetic circuit. CONSTITUTION:A 1-chip microcomputer for electronic calculator/game, etc., outputs the contents of a program memory to the outside of an LSI 1 at test and inspects the data written in a ROM.M. In such a microcomputer it is inhibited to read the contents of the program memory directly to the outside. Thus an arithmetic operation is carried out between the data of the program memory and the output data of an optional number counter that can preset the optional value given from the outside. Then this arithmetic result is outputted. As a result, the secrecy of the software can be protected against the outsiders trying to copy the software. |
