The result of the "modular replacement of combinational switching networks method" by Schmidt and Metze1is discussed in this correspondence. It shows that the switching function of the last example used to demonstrate the power of the developed computer programs, can be implemented in "library modules" at less than half the cost of the best computer result. With other "non- library" modules being ordinary integrated circuits, an even better result can be obtained.

For many years two-input NAND, AND, NOR, OR and EX-OR gates have been commercially available as cheap quad TTL integrated circuits (IC's). Ideas on quad programmable two-input gates (three inputs per gate) have been published in the literature but have not reached the commercial stage [1]. However, complicated and expensive arithmetic logic units (ALU's) programmable to perform 16 different functions on two 4-bit arguments have become commercially available. The four sections of ALU's are not individually programmable.

Reflected binary (RB) code words plus an even parity check can be considered as signed digit (SD) representations of the corresponding natural binary (NB) code words. The SD code words allow a simple serial conversion with the least significant bit leading of their digits forming the RB code words into the NB code words.

In digital integrated circuits (IC's) a synchronous binary-rate multiplier is commercially available, generating a programmable number of output pulses during each internal counting cycle having a length equal to a power of two. These output pulses are not equally divided over that fixed internal counting cycle and the generated binary rate has a fixed denominator. In this note a new type of binary-rate multiplier is described. This circuit allows the programming of both numerator a and denominator b of the rate of the numbers of output and input pulses. It operates in such a way that during a cycle of b pulses the circuit output generates a number of pulses divided over the cycle of b pulses as equally divided as is possible in digital systems.