Redundancies and don't cares in sequential logic synthesis
Journal of Electronic Testing: Theory and Applications
On removing redundancy in sequential circuits
DAC '91 Proceedings of the 28th ACM/IEEE Design Automation Conference
Logical redundancies in irredundant combinational circuits
Journal of Electronic Testing: Theory and Applications
Theory and Design Switching Circ
Theory and Design Switching Circ
Classification of Faults in Synchronous Sequential Circuits
IEEE Transactions on Computers
Testable design of non-scan sequential circuits using extra logic
ATS '95 Proceedings of the 4th Asian Test Symposium
Testable design of non-scan sequential circuits using extra logic
ATS '95 Proceedings of the 4th Asian Test Symposium
Hands-on, simulated, and remote laboratories: A comparative literature review
ACM Computing Surveys (CSUR)
Constructing reality: A study of remote, hands-on, and simulated laboratories
ACM Transactions on Computer-Human Interaction (TOCHI)
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Design of irredundant and fully testable nonscan sequential circuits is a major concern of logic synthesis, as the presence of undetectable faults may render an ATPG intractable. This paper outlines some intriguing properties of isomorph faults, which are sequentially undetectable as well as redundant. An isomorph fault in a sequential circuit makes the state diagram of the faulty machine identical to that of the fault-free machine under certain renaming of states. Examples of reduced sequential machines whose circuit realization is combinationally irredundant, but isomorph-redundant, are hard to construct and very little is known about them. In this paper, many curious examples of such sequential circuits are presented wherein a single stuck-at fault causes isomorphic faulty machines. An infinite family of such circuits may, in fact, be constructed. It is shown that even two-level irredundant circuits obtained by synthesis tools may admit isomorph-redundancy under multiple stuck-at faults. Various classifications and related properties of isomorph faults are also reported. These results reveal new insight and understanding of redundancy in sequential circuits.