| 摘要 |
PURPOSE:To improve the versatility of a digital signal processor (DSP) by providing a decoding circuit to decode an encoded program on the basis of a decoding code taken out by a control circuit. CONSTITUTION:At the time of operating the DSP 11, at first, a microcomputer 12 sends a control signal to the DSP 11, and afterwards, it starts the serial transfer of a decoding key code and the encoded program in order. A decoding key extraction circuit 4 is turned into an operating state by the impressing of the control signal, and when it inputs the decoding key code transferred first by eight bits, it sends this decoding key code to the decoding circuit 15 so as to preset it in a random number generation circuit in the decoding circuit 15. The decoding circuit 15 decodes the program by taking the E-OR output of a random number generated successively and the instruction code of the encoded program inputted successively. |
