SEMICONDUCTOR TEST CIRCUIT

PURPOSE:To facilitate comparing of the timing at am external terminal with a timing signal produced internally by a logic circuit, facilitate grasp of the internal condition of the circuit, and shorten the time required to analyze the cause of failed operation. CONSTITUTION:A semiconductor test circuit is equipped with a selector 3 to select one of the timing signals produced internally by a logic circuit, a select register 1 to hold the value set externally in order to select the timing signal, a decoder 2 to decode the value of the select register 1 for controlling the selector 3, and a counter 4 for counting the timing signals. The circuit also includes a count register 5 for setting the count, a comparator 6 for comparing the count with the value on the count register, a selector 7 to select necessary signals among status signals produced internally by the logic circuit, and a status register 8 to hold the status signal emitted by the selector 7.