Apparatus for testing an integrated circuit is described, including a set of signal conductors for communicating signals to respective external conductors of the integrated circuit. The apparatus also includes a tester comprising circuitry for outputting a signal. An interposer is electrically coupled between the set of signal conductors and the tester. The interposer comprises circuitry for selecting a set of signals between the set of signal conductors and the tester and outputting the set of signals. A signal processing apparatus is coupled to receive the set of signals, and the signal processing apparatus is operable to evaluate a parameter associated with each signal in the set of signals.