Digital device testing apparatus and method

Testing apparatus monitors signals at selected test points in a tested device. An operator specifies sets of signals defining a display window during which all signals at the selected test points will be available to the operator for immediate or later examination. One set of signals defines the beginning of the window. Another set defines the end of the window, but only after other sets or conditions, also specified by the operator, occur. For each set, the operator specifies test points monitored, signal states expected and what happens when the expected states occur.