Formalized timing diagrams

Traditionally, the timing behavior of digital circuits has been described using timing or waveform diagrams. These diagrams concisely represent the shape of the waveforms that are observed at the interface of a circuit and the temporal relationships between their edges. Timing information takes two principal forms: propagation delays that abstract the internal implementation of the circuit and timing constraints that specify how the circuit can be used by its environment. The author proposes a formalization of the concepts and notations used in timing diagrams that enable them to be used in conjunction with hardware description language specifications of the circuit's internal function. WAVES, an interactive timing diagram editor that was designed to embody these formalisms is also described. WAVES is unique in that it captures complex timing behaviour including concurrent, conditional, and iterative event sequences.<>