| 摘要 |
PURPOSE:To quickly attain the test of an FF by providing a deciding circuit, which decides the coincidence between the non-inverted output and the inverted output of the flip-flop(FF) on an output stage, and a circuit, which selectively fetches one output of the FF and the output of the deciding circuit. CONSTITUTION:An FF 2 is provided on the output stage of a programmable logic array(PLA) 1. A deciding circuit 3 decides whether or not the non-inverted output of the FF 2 corresponds to the inverted output. An output selecting circuit 4 selectively fetches one output of the FF 2 and the output of the circuit 3 to an output terminal is response to a control signal. At the time of testing, when the operation of the FF 2 is normal, the output is fetched to the terminal 5, when the operation is abnormal, a signal to indicate the coincidence is fetched to the terminal. Consequently without taking into consideration feedback to an AND array, and regardless of a programmed logical function, whether or not the FF is normally operated can be easily and promptly tested. |
