Block Marking and Updating Coding in Test Data Compression for SoC

A novel test data compression coding scheme, block marking and updating coding, is proposed in this paper. Test data in the test set was divided into successive fixed-length vectors, called blocks, and then they were marked according to their compatibility compared with a reference vector. An operation that is similar to difference and a technique that strategically fills in don ´t-care bits are combined to increase the probabilities of compatibility or inverse compatibility. It effectively compresses test data and its decompression structure is very simple. Experimental results of ISCAS-89 benchmark circuits show that the scheme is very effective.