Universal Logic Modules Research Articles

Optimal and Near-Optimal Universal Logic Modules with Interconnected External Terminals

A universal logic module (ULM) with interconnected external terminals contains m input terminals and s auxiliary function terminals. The module implements the function U( Z 1 , Z 2 ,...,Z m ) such that every Boolean function of n variables f( x 1 , x 2 ,* .* * X, n ) can be realized by an appropriate substitution of an element of 5= { x l ,x 1 ,x 2 ,x 2 ,...,X n ,x n ,g 1 ,g2,..., gs} for each zj. An improved lower bound on the minimum number of terminals of a ULM of this type is derived. It is shown that certain of the best-known designs are in fact optimal. Improved designs are presented for ULM's of nine and ten arguments.

Correction to "Design and application of a modified universal logic module"

Correction to "Design and application of a modified universal logic module"

Design and application of a modified universal logic module

The basic concept of an n-variable universal logic module (ULM-n) as developed by Yau and Tang is extended so that the input control functions are simple two-bit binary codes and not determined by one of the n variables. Although the resulting design is not a minimum pin configuration, it has the advantage that the control variables are 0 and 1. Basic ULM-2 and ULM-3 are developed and a method of using them to implement higher variable ULM's is also considered.

Universal Base Functions and Modules for Realizing Arbitrary Switching Functions

Universal base functions (UBF's) which are generalizations of universal logic functions are defined. An (n, m, r)-UBF can be implemented as a single module (UBM) with n+m inputs and 1 output. An arbitrary n-variable switching function f n (X) is then realized on the fixed UBM by realizing a suitable set of m r-variable functions with which to drive m inputs of the UBM, the remaining n inputs being driven by X. The fan-in of a UBM for r ?2 is shown to be considerably less than that of a universal logic module (a special case corresponding to r = 1). Specific UBF's are proposed for r = 2 in which m is on the order of 60 percent of the value obtained by using the UBF defined by the familiar Shannon decomposition formula. This is close to the theoretical lower bound on m. The use of UBM's provides a new way to realize an arbitrary function or set of functions, completely specified or otherwise, by assembling a small number of circuits selected from a small set of standard logic modules of limited fan-in. For the case r = 2, the number of two-input devices required to drive the m inputs of the UBM is often considerably less than m. DON'T CARES can be used to advantage to reduce this number still further.

Universal Logic Modules of a New Type

By considering universal logic modules whose terminals may be interconnected, new designs are presented for six, nine, and ten arguments, whose numbers of terminals represent substantial improvements over previously known designs.

Comments on "Universal Logic Modules and Their Applications"

Research on universal logic modules has taken place with two directed aims: 1) the production of universal microcircuits, and 2) the design of adaptive logic systems. This correspondence comments on the progress in these two fields.

Universal Logic Modules and Their Applications

Recent advances in integrated circuit technology and its potential advantage in logical design have motivated the search for modular synthesis techniques for logic networks. This problem may be divided into two parts: find appropriate modules; and develop efficient synthesis techniques for logic networks using a minimum number of modules. In this paper a new type of universal logic modules (ULM's) called the Q-type is presented. The Q-type ULM's are superior to the existing ULM's in the sense that they require fewer input/output terminals when n≥6 where n is the number of input variables of the ULM. Various techniques for synthesizing a logic network with a small number of ULM's are discussed. A much simpler type of modules, which is suitable to realize any symmetric or partially symmetric function and can be used as auxiliary building blocks for realizing any given logic function, is presented. A special kind of ULM's, called serially controlled ULM's which has only n+ 3 input/ output terminals, is also presented. For a ULM of this kind the signals for specifying the logic function to be realized are serially applied to one of its input terminals.