In systems consisting of interacting datapaths and controllers and utilizin
g built-in self test (BIST), the datapaths and controllers are traditionall
y tested separately by isolating each component from the environment of the
system during test. This work facilitates the testing of datapath/controll
er pairs in an integrated fashion. The key to the approach is the addition
of logic to the system that interacts with the existing controller to push
the effects of controller faults into the data flow, so that they can be ob
served at the datapath registers rather than directly at the controller out
puts. The result is to reduce the BIST overhead over what is needed if the
datapath and controller are tested independently, and to allow a more compl
ete test of the interface between datapath and controller, including the fa
ults that do not manifest themselves in isolation. Fault coverage and overh
ead results are given for four example circuits.