| 摘要 |
PURPOSE:To realize a key code system with high confidentiality and low cost, by setting a key code data and storing it corresponding to an operation circuit different at each decoder. CONSTITUTION:A key code circuit 10N corresponding to a decoder consists of a memory 16N, an operation circuit 17N and a key code register 18. A key code data is set to the memory 16N corresponding to the operation circuit 17N different from decoder for storage. The operation circuit 17N makes a specified operation processing and gives output to a key code register 18. The key code register 18 stores the key code from the operation circuit 17N and supplies the key code to a decoding circuit 9 in response to the reading signal from the decode circuit 9. |
