13 2-17.   For which of the following reasons would you classify an IC as a "black box" device? 1.   Because ICs are always black in color 2.   Because all you can check are the inputs and outputs, not the internal operation of ICs 3.   Because printed circuit boards that contain ICs cannot be repaired 4.   Because ICs are designed to be repairable components 2-18.    Test equipment used to detect the logic state of a digital IC should have which of the following characteristics? 1.   A capability of measuring rms voltages 2.   A frequency response in excess of 40 GHz 3.   A high input impedance 4.   A low input impedance 2-19.   Which of the following statements describes) the use of logic clips? 1.   Logic clips are designed to monitor the input and output of an IC simultaneously 2.   Logic clips can only be used to test an IC that is out of the circuit 3.   Logic clips can only be used with flat pack ICs 4.   All of the above 2-20.   For which of the following purposes are logic comparators used? 1.   To test linear ICs 2.   To compare different types of ICs 3.   To inject pulse trains into digital ICs 4.   For in-circuit testing of digital ICs by comparing them with reference ICs 2-21.   Which of the following is an advantage of using a logic probe instead of an oscilloscope to test a digital IC? 1.   Logic probes are usually larger than an oscilloscope but much lighter 2.   Logic probes have a low input impedance 3.   Logic probes are battery powered and do not react to line voltage variations 4.   Logic probes are capable of detecting short-duration pulses that most oscilloscopes cannot display 2-22.   For which of the following purposes are logic pulsers used? 1.   To detect the logic state of digital ICs 2.   To detect the logic state of linear ICs 3.   To inject a pulse or pulse train into a logic circuit 4.   To inject a 1-kHz sine wave into a circuit for signal tracing 2-23.   Which of the following is a typical application for a logic analyzer? 1.   To program EPROMs 2.   To test individual logic ICs 3.   To analyze the spectral purity at the output of a logic IC 4.   To perform timing analysis by monitoring and comparing more than one timing signal simultaneously