PARTIAL-SCAN BUILT-IN SELF-TESTING CIRCUIT HAVING IMPROVED TESTABILITY

The testability of a near-acyclic circuit (14) can be enhanced by the addition of one or more control points (36) and observation points (34) to allow for increased observability and controllability of selected nodes (28). The control points (36) and/or test points (34) are added by first computing the controllability, observability and fault detection probability at each node. A fault is then selected. If either the controllability or observability for such fault is not inside a prescribed value range, and the fault detection probability is below a prescribed value, then either a control point (36) and/or a observation point (34) may be added.