Design for autonomous test

A technique for modifying networks so that they are capable of self test is presented. The major innovation is partitioning the network into subnetworks with sufficiently few inputs that exhaustive testing of the subnetworks is possible. Procedures for reconfiguring the existing registers into modified linear feedback shift registers (LFSR´s) which apply the exhaustive (not pseudorandom) test patterns or convert the responses into signatures are described. No fault models or test pattern generation programs are required. A method to modify CMOS circuits so that exhaustive testing can be used even when stuck-open faults must be detected is described. A detailed example using the 74181 ALU is presented.