| 摘要 |
PURPOSE:To achieve a reduction in an overhead while reducing the number of input/output terminals necessary for testing by arranging a circuit to let a specified FF transmit data to be supplied to an input terminal as intact to an output terminal by a control signal from outside. CONSTITUTION:A circuit contains a transfer gate T5 which is connected in parallel to a transfer gate T3 of an FF12a to be turned ON or OFF by a control signal DTC and an inversion signal thereof and a transfer gate T6 which is connected in series to the transfer gate T4 between an output terminal of an inverter IV4 and an input terminal of an inverter IV3 to be turned ON or OFF opposite to the gate T5 by a control signal DTC and an inversion signal thereof. An FF12 containing the gates T5 and T6 acts as normal FF to let data through irrelevant to a clock signal CK if the control signal DTC is at an active level and if the control signal is at a nonactive level, the data at an input terminal is taken in while being let through when the signal CK is at an active level. When the signal is at a nonactive level, the data taken in is held. |
