Two contributions to redundancy theory

By analysing an ideal model of a redundancy scheme, a measure for the reliability improvement produced by a redundancy scheme is found; and it is shown that for real redundancy schemes this measure is effectively independent of the size of system to which the scheme is applied. Other advantages of the measure are that it is relatively easy to evaluate, and has a good sensitivity characteristic. This measure, together with a redundancy "cost" factor, represents the performance of a redundancy scheme more generally than was previously possible. A new high performance redundancy scheme - "radial logic" is described, and its error correcting action explained. It can be applied to combinational and sequential logic circuitry, and in this application appears to have a better performance than other schemes, as well as being simple to design, and offering considerable flexibility in the degree of error correction.