| 摘要 |
PURPOSE:To prevent data from being written erroneously to a storage device by providing a gate with regard to a scan-in signal for setting a write control register, and inhibiting an input to the write control register at the time of a regular operation. CONSTITUTION:The control system is constituted so that a scan-in (SI) signal sent out of a scan control circuit 3 is inputted to a write control register 1 through a gate 4. Usually, an input level of the gate 4 is set to a prescribed level so that the scan-in (SI) signal is not inputted to the write control register 1. At the time of testing parts, the input level of the gate 4 is set to other level and the scan-in (SI) signal is inputted to the write control register 1 so that that which is selected by a scan address (SAD) signal is set. In such a way, at the time of setting the contents of the control register 1 to an arbitrary value, setting to the write control register 1 is inhibited and erroneous write to a storage device 2 is prevented. |
