Models and methods checking mantissas by inequalities for on-line testing of digital circuits in critical applications

摘要

This paper is devoted to a problem of on-line testing efficiency in digital components of safety-related systems taking into account their design for operation in two modes: normal and emergency. Approach to increase of on-line testing method trustworthiness in checking of approximate results is offered. Approach is based on distinguishing of the essential and inessential errors caused by faults of digital circuits in most and least significant bits of result and on development of on-line testing methods for circuits with the raised dual-mode functional checkability. For operations of multiplication and division of mantissas, the result models which are its upper and lower boundaries are offered. On a set of models of result the methods checking mantissas by inequalities with the dominating detection of essential errors are defined and evaluated. The two-mode functional checkability is raised by abbreviation of array structures when on-line testing methods are used for the iterative array multipliers and dividers executing the truncated operations.