| 摘要 |
PURPOSE:To test the function of an apparatus by the reduced number of testing signals, by serially performing the giving and receiving of the input signal of testing data and the output signal corresponding thereto and determining a signal transmitting direction corresponding to each test terminal on the basis of a control signal. CONSTITUTION:The third terminals of switch circuits SW1-SWn are connected to input/output circuits IO1-IOn. The circuits IO1-IOn perform operation as input or output circuits corresponding to an operation mode signal and the giving and receiving of the input and output signals of testing data is performed with respect to a logical circuit LOG. A testing circuit PSCV serially transmits the testing input signal supplied from a terminal TDI according to a control signal S/P and this testing input signal is parallelly sent out to each circuit from terminals T1-Tn. Then, the output signal corresponding to said input signal is received from the circuit LOG parallelly and subsequently transmitted serially to be outputted from external terminal TOD. By this method, the function of an apparatus can be tested by the reduced number of signals. |
