Test access mechanism for diagnosis based on partitioining scan chains

A method of test access mechanism, comprising:

• capturing test response data of a circuit under test in scan cells, the scan cells forming a plurality of scan chains;
• generating check values for the test response data based on expected test response data while the test response data are being shifted out from the plurality of scan chains;
• and
• generating partition pass/fail signals based on the check values using a plurality of partitioning scheme generators while the checked values are being generated, each of the plurality of partitioning scheme generators configured to generate one of the partition pass/fail signals for one of partitioning schemes, each of the partitioning schemes dividing the scan cells into a set of non-overlapping partitions, each non-overlapping partition in the set of non-overlapping partitions including a set of scan cells from different scan chains.