| 摘要 |
PURPOSE:To omit an external pin that sets only an internal mode by providing the internal mode setting storage circuits on the data and address pins in a normal operation mode, latching the signals inputted from those external pins in the storage circuits, and using the output signals received from these storage circuits as the internal mode setting signals. CONSTITUTION:In a normal mode the data inputted via a data pin 19a are latched synchronously with a clock signal and fetched by a microprocessor via a data input line 21b. Then the processed data are outputted via a data output line 21a and taken out via the pin 19a. In a test mode an internal mode setting signal is inputted via the pin 19a synchronously with a resetting signal 20 and then latched by a storage circuit 25 added to the pin 19a. The output signal 24 of the circuit 25 is used as a scan path selecting signal. Thus it is possible to omit an exclusive external pin that sets an internal mode. |
