A fault detect mechanism is described for hardwired control logic. The mechanism takes advantage of inherent redundancy in the control logic design style which assigns a unique flip-flop to each machine state. The mechanism is capable of detecting all single stuck-at faults, as well as many multiple faults and intermittents within the control section.

A bound is derived on the number of low-weight sequences an L-step observable nonsingular-autonomous finite-state machine is capable of producing.

It is shown that the numberMof binary-valuedn-tuples having fractional weight\deltaor less,0 < \delta \leq \frac{1}{3}, such that no twon-tuples agree in anyLconsecutive positions, is bounded by2^{2LH(\delta)+1}. A set ofn-tuples is constructed to show that this bound is not likely to be improved upon by any significant factor. This bound is used to show that the ratiod_{DD}/n_{DD}of definite-decoding minimum distance to definite-decoding constraint length is lower bounded byH^{-l}[\frac{1}{6} \cdot (1 - R)/ (1+R)]asn_{DD}grows without bound.

A counterexample to a conjecture on the number of constraint lengths required to achieve the free distance of a rate1/nsystematic convolutional code is presented.