Functional level testability analysis for digital circuits

A general approach is proposed for calculating controllabilities and observabilities of signals in sequential and combinational circuits at the functional level. The methods and algorithms are based on alternative graphs which are an extension of binary decision diagrams. The algorithms are general and can be easily adjusted for calculation of different testability measures. A structured expression of the combinational controllability is presented, which allows to regard initiability and different heuristic controllability measures as components of the probabilistic controllability