This letter describes a novel design of a combinational network to facilitate the single stuck-at fault detection problem. The design makes use of EXCLUSIVE-OR modules as control elements and the observability has been increased by providing an additional observable output which is the output of an additional AND gate in the network. Such a design of a combinational network with n primary input variables will require only (n + 1) predefined test input patterns belonging to the set T = {11...11,011...11,101 ...11, ........., 11 ... 110} for the detection of stuck-at single s-a-0 and s-a-1 fault on a line of the network. As a result, the extremely difficult task of test generation can be easily dispensed with.

A novel design of a combinational network to facilitate fault detection

In this paper a new and a graph theoretic approach based on Petrinet model for calculating any order Boolean Difference has been suggested. The concept of Boolean Difference has also been extended to generate a complete test set for all possible multiple faults on any number of lines of a logic circuit. The approach is based on the study of the system of open paths in an acyclic graph and on some basic theorems established in the paper. Unlike algebraic methods, this method is suitable for machine computation and is therefore, applicable to arbitrarily large circuits.

A graph-theoretic multiple logic fault analysis through Petri-nets

A direct approach for single and multiple fault test set generation on any number of lines of a logical circuit has been described in this paper. The present paper simplifies the results of Ku and Masson [2] for which only some visual inspections are needed rather than going through tedious steps of algebraic manipulations. This method is thus easily applicable to arbitrarily large combinational circuits, whether it is fan-out free or with fan-out nodes.

An efficient algorithm for single and multiple fault test sets generation

A method for finding out the prime implicants and hence the minimal sum(s) of switching functions containing essential prime implicants, cyclic type prime implicants or functions with don't care terms has been suggested in this paper. This paper describes a simpler procedure for sorting out the EPIs while forming the combination tables and to select the other essential terms needed for the minimal cover of the function by a new technique known as the “Formation of combination chain” decribed in the method. The method thus does away with the need for the successive PI tables as suggested in Q-M method.

A simpler method for minimization of switching functions

This paper reports on the development of a novel scheme as an alternative to Susskind's method [A.K. Susskind, Testing by verifying Walsh coefficients, Proceedings of the 11th Annual Symposium on fault-tolerant computing, June 1981, pp. 206-208.] for detection of struck-at faults in combinational logic circuits. The main idea in the present scheme is to extend an existing design of the combinational network under test in minterm format by some logic checking the correctness of all input-output mappings by computing only one novel parameter after cycling through all 2n input combinations of a circuit with n inputs. Thus the present scheme uses 2n n-bit input patterns once to a circuit while Susskind's method uses twice that many. So it provides substantially less work than that needed in Susskind's method. Furthermore, the tester needed to implement the present scheme is a simplified version of that needed in Susskind's method.

Pramode Ranjan Bhattacharjee

Papers

An efficient algorithm for single and multiple fault test sets generation

A simpler method for minimization of switching functions

Quick detection of faults in combinational networks designed in minterm format by computing a single novel parameter