The features of the concurrent error-detection systems of combinational logic circuits based on the search for groups of symmetrically-independent outputs construction

The authors of the article found that in the use of classical sum codes (Berger codes) and a some of their modifications in the combinational circuits testing organization it is possible to detect both unidirectional and part of non-unidirectional errors in the data vectors. It is shown that it is possible to search for such groups of outputs of combinational circuits where only symmetrical errors occur due to stuck at-faults of elements of the internal structure of the circuits. Such groups of outputs are designated as symmetrically-independent outputs (SI-groups of outputs). The conditions of belonging of the group of outputs of the combinational circuits to the SI-groups of outputs are determined. It is shown that each SI-group of outputs can be controlled using a separate testing subsystem based on the code with the detection of any non-symmetrical errors (in particular, and any non-symmetrical errors up to certain multiplicities). The ways of searching for SI-groups of outputs in the combinational circuits testing organization are presented