Procedures for the modeling and simulation of faults in LSI devices at functional level are developed. Generalized functional level fault classes are defined for digital LSI devices such as microprocessor and peripheral chips. General procedures to inject functional level faults in the LSI chip models are illustrated with the help of various examples. Next, techniques of automating the simulation of the faulty systems are discussed. Finally, simulation of faults at the functional level is compared with the gate level simulation in case of INTEL 8212 (8 bit I/O) chip. / Master of Science