| 摘要 |
PURPOSE:To obtain a device having a circuit which can independently inspect an instruction decode circuit independently of a function constituting element, by outputting a data in a shift register to an output terminal or an input/output terminal only at an inspection mode state. CONSTITUTION:A shift register and a check mode control circuit are provided and data in the shift register is outputted to an output terminal or an input/ output terminal only at the check mode state. For example, an instruction code inputted from an instruction decode circuit 4 is interpreted, corresponding control signals C1-Cn are transmitted, a check mode control circuit 8 makes a parallel input control signal 9 of the shift register 7 effective and the control signals C1-Cn are fetched in the shift register 7. A serial transfer clock 10 is applied to the shift register 7 to move the data to be fetched and an output 12 of the shift register 7 is inputted to an AND gate 13. When an output control signal 11 is at high level, the signal is outputted to an external to an external terminal 14 via the AND gate 13. |
