Edward J. McCluskey

Concurrent error detection using watchdog processors-a survey

Concurrent system-level error detection techniques using a watchdog processor are surveyed. A watchdog processor is a small and simple coprocessor that detects errors by monitoring the behavior of a system. Like replication, it does not depend on any fault model for error detection. However, it requires less hardware than replication. It is shown that a large number of errors can be detected by monitoring the control flow and memory-access behavior. Two techniques for control-flow checking are discussed and compared with current error-detection techniques. A scheme for memory-access checking based on capability-based addressing is described. The design of a watchdog for performing reasonable checks on the output of a main processor by executing assertions is discussed. >

Probabilistic Treatment of General Combinational Networks

In this correspondence two methods are given for calculating the probability that the output of a general combinational network is 1 given the probabilities for each input being 1. We define the notions of the probability of a signal and signal independence. Then several proofs are given to show the relationship between Boolean operations and algebraic operations upon probabilities. As a result of these, two simple algorithms are presented for calculating output probabilities. An example of the usefulness of these results is given with respect to the generation of tests for the purpose of fault detection.

Built-In Self-Test Techniques

A system that includes self-test features must have facilities for generating test patterns and analyzing the resultant circuit response. This article surveys the structures that are used to implement these self-test functions. The various techniques used to convert the system bistables into test scan paths are discussed. The addition of bistables associated with the I/O bonding pads so that the pads can be accessed via a scan path (external or boundary scan path) is described. Most designs use linear-feedback shift registers for both test pattern generation and response analysis. The various linear-feedback shift register designs for pseudorandom or pseudoexhaustive input test pattern generation and for output response signature analysis are presented.

Curriculum 68: Recommendations for academic programs in computer science: a report of the ACM curriculum committee on computer science

This report contains recommendations on academic programs in computer science which were developed by the ACM Curriculum Committee on Computer Science. A classification of the subject areas contained in computer science is presented and twenty-two courses in these areas are described. Prerequisites, catolog descriptions, detailed outlines, and annotated bibliographies for these courses are included. Specific recommendations which have evolved from the Committees 1965 Preliminary Recommendations are given for undergraduate programs. Graduate programs in computer science are discussed, and some recommendations are presented for the development of masters degree programs. Ways of developing guidelines for doctoral programs are discussed, but no specific recommendations are made. The importance of service courses, minors, and continuing education in computer science is emphasized. Attention is given to the organization, staff requirements, computer resources, and other facilities needed to implement computer science educational programs.

An experimental chip to evaluate test techniques experiment results

This paper describes the testing of a chip especially designed to facilitate the evaluation of various test techniques for combinational circuitry. The different test sets and test conditions are described. Several tables show the results of voltage tests applied, either at rated speed or 2/3 speed, to each defective CUT. Data for CrossCheck, Very-Low-Voltage, IDDQ and delay tests are also given.

Which concurrent error detection scheme to choose

Concurrent error detection (CED) techniques (based on hardware duplication, parity codes, etc.) are widely used to enhance system dependability. All CED techniques introduce some form of redundancy. Redundant systems we subject to common-mode failures (CMFs). While most of the studies of CED techniques focus on area overhead, few analyze the CMF vulnerability of these techniques. In this paper, we present simulation results to quantitatively compare various CED schemes based on their area overhead and the protection (data integrity) they provide against multiple failures and CMFs. Our results indicate that, for the simulated combinational logic circuits, although diverse duplex systems (with two different implementations of the same logic function) sometimes have marginally higher area overhead, they provide significant protection against multiple failures and CMFs compared to other CED techniques like parity prediction.

Very-low-voltage testing for weak CMOS logic ICs

In this paper we propose a very-low-voltage (VLV) testing technique for CMOS logic ICs. Voltage dependence of CMOS logic circuit operation in the presence of resistive shorts and hot carrier damage is studied. It is shown that at certain much-lower-than-normal power supply voltage, weak CMOS logic ICs due to the presence of these flaws can be forced to malfunction while truly good ICs continue to function. Very-low-voltage testing also detects pattern dependent faults caused by resistive shorts. Because of its simplicity and because there is no overhead associated with it, very-low-voltage testing can easily be applied to chips and circuit boards as a production test, field test, or failure diagnosis technique.<<ETX>>

Fault Equivalence in Combinational Logic Networks

This paper is a study of the effects of faults on the logical operation of combinational (acyclic) logic circuits. In particular, the conditions whereby two different faults can produce the same alteration in the circuit behavior are investigated. This relationship between two faults is shown to be an equivalence relation, and three different types of equivalence relations are specified. Necessary and sufficient conditions for the existence of these equivalence relations are proved. An algorithm for determining the equivalence classes for one of the types of equivalence is presented. Other types of algebraic properties of faults are discussed.

Diagnosing CMOS bridging faults with stuck-at fault dictionaries

It is shown that the traditional approach to diagnosing stuck-at faults with fault dictionaries generated for stuck-at faults is not appropriate for diagnosing CMOS bridging faults. A novel technique for using stuck-at-fault dictionaries to diagnose bridging faults is described. Teradynes LASAR was used to simulate bridging and stuck-at faults in a number of combinational circuits, including parity trees, multiplexers, and the 74ASCI181 4-b, 16-function ALU (arithmetic and logic unit). When the traditional technique was used, between 30%-50% of the bridging faults were mis-diagnosed, with the presence of a failure indicated on a fault-free node. In addition, as the stuck-at-fault diagnostic ability of a test increased, the bridging fault diagnostic ability decreased. By use of the new technique. over 92% of the bridging faults in the circuits used for this research were diagnosed correctly and less than 4% led to misleading diagnoses.<<ETX>>

RESISTIVE SHORTS WITHIN CMOS GATES

This paper studies the effects of shorts within CMOS gates. Dynamic as well as static gate properties are analyzed as a function of the short’s resistance. Increased propagation delay is found to be a common dynamic effect. Circuit behavior can change drastically with small variations in a short’s resistance. It is found that faults caused by transistor gate-to-source and gate-to-drain shorts can be dependent not only on inputs of gates containing the faults but also on other signals. This pattern dependence due to “resistive shorts” can invalidate tests generated using normal TPG procedures.