A measure of the minimum cost of a logical network is important in the evaluation of such networks. A hypothesis is investigated which states that the average minimum cost depends on both the number of input variables and the entropy (``entropy'' in this sense is based on the probability of a ``1'' in the functions' truth table) of the function realized. Some experimental results are presented to support the hypothesis.

In designing a self-checking processor, it is essential to recognize the types of failures that are most probable. Matching the checking techniques with the type of faults that are expected to occur should yield the best result with the least amount of hardware. The microprogram control will consist of integrated circuits: large-scale integration (LSI) for the memory and small-scale integration (SSI) for the associated control logic. Because of the density of chips on a plug-in package and the physical proximity of the devices on an integrated circuit, multiple faults within a single circuit are highly probable. The types of faults within a circuit have been analyzed and found to be of the type which would tend to affect the bits in a unidirectional manner. Also the failed bits would probably be adjacent rather than randomly dispersed throughout-the microprogram store word.

Dynamic microprogramnming (i. e., utilizing a READ/ WRITE microstorage) allows the structure of a computer to be altered to suit a problem at hand and results in major efficiencies (an order of magnitude) in running time for nonarithmetic programs (e. g., compilers).