Abstract: The execution over time of software code is displayed such as on the screen of a cathode ray tube by inserting probes into blocks of code and displaying each probe as the various blocks of code are executed. The execution of various blocks of code is presented in a spatial manner to provide information regarding the sequential operation of, and the temporal relationships among, the various blocks of code. This software code operating information is displayed in real time or may be stored for subsequent recall and display. The start and stop of observation of software code operation may be preprogrammed for automatic monitoring, or monitoring may be triggered by an event. By visually observing the operation of the software program, correlation can be established between execution of the various blocks of code and expected system responses or events leading to a better understanding of program operation and design.