US Patent 7263639 Combinatorial at-speed scan testing

A combinatorial at-speed scan testing. A processor including a plurality of distributed slave counters. Each distributed slave counter coupled to a group of scan chains, each distributed slave counter to generate shift-enable-flop signals to be received by the group of scan chains coupled to each distributed slave counter, the shift-enable-flop signals based at least in part on an external shift-enable signal received by the processor. A scan test controller coupled to the plurality of distributed slave counters to provide control signals to the plurality of distributed slave counters to perform an at-speed test of the processor.