Reducing the storage requirements of a test sequence by using a background vector

We describe a storage scheme for functional test sequences where a test sequence T is associated with a primary input vector B called a background vector. T is stored by storing only the differences between its test vectors and B. We describe a procedure for computing a background vector B for a given test sequence T. We also describe a procedure that modifies T so as to reduce its storage requirements with respect to B. We present experimental results demonstrating that the single background vector B, computed based on T, allows T to be modified such that a vast majority of its entries are equal to the corresponding entries of B. Consequently, storage of T reduces to storage of a small number of entries.