Two classes of incompletely specified sequential machine (ISSM) are described, which contain the class of input-restricted machines defined by McCluskey [1] and Unger [2] as special cases. These new classes of machine can be identified at the conclusion of a modified (and more efficient) version of the standard compatible pairs-table analysis of Paull and Unger [3]. For such machines only maximal compatible classes need be considered in finding the minimal state machine, and any such covering selection is also closed. An algorithm is presented which is fast and efficient both for hand-use and computer implementation.

The binary rate multiplier is a device which has been used for many years in hybrid computing (operational digital techniques) and control systems as a means for generating a pulse train of average frequency proportional to the value of a binary number stored in a register. In general, the pulse spacing is irregular and the number of pulses generated in a given time fluctuates above and below the number which would be produced by a perfectly regular pulse train at the same average frequency. These fluctuations constitute a short-term frequency error, the value of which is an important parameter in the design of pulse rate digital systems incorporating binary rate multipliers. This article analyzes the conditions under which maximum positive and negative errors occur, and expressions are derived from which the magnitude of such errors may be calculated.