Maximal diagnosis of interconnects of random access memories

This paper presents an approach for the maximal diagnosis of all faults (stuck-at, open and short) in the interconnect of a random access memory (RAM); and the interconnect includes data and address lines. This approach accomplishes maximal diagnosis under a complex model in which the lines in the interconnect of the RAM can be affected by multiple faults. Maximal diagnosis consists of detection and location of all diagnosable faults as well as type identification of multiple faults affecting each line. The proposed algorithm (referred to as the Improved Maximal Diagnosis Algorithm, or IMDA) requires max{n, m-1}+n+3 WRITE and max{n, m}+2n READ, where n is the number of address lines and m is the number of data lines. IMDA executes in three different steps: the first step diagnoses the data lines (and in particular the stuck-at faults); the second step accomplishes maximal diagnosis of the shorts (involving either the data lines only, or the data and address lines); and the third step completes the diagnosis of the address lines.