Ramifications of Metastability in Bit Variables Explored Via Simpson's 4-Slot Mechanism

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  2. Dr Stephen Paynter
  3. Neil Henderson
  4. Dr James Armstrong
Author(s)Paynter SE, Henderson N, Armstrong JM
Publication type Report
Series TitleSchool of Computing Science Technical Report Series
Legacy DateJanuary 2003
Report Number789
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Protocol descriptions often fail to take metastability into account. Metastability, however, can undermine protocols which depend on shared bits. In this paper, a series of increasingly realistic models of bits are developed in CSP, to explore the implications of metastability for Simpson's 4-Slot asynchronous communication mechanism. It is shown that the 4-Slot mechanism with realistic bit models preserves data-coherence, freshness, and sequencing, and is Lamport-atomic. We demonstrate that metastability can undermine the correctness of protocols demonstrated correct with Lamport-safe models of bits; furthermore, realistic bit models can demonstrate protocols correct which Lamport-safe bit models would suggest were incorrect.
InstitutionSchool of Computing Science, University of Newcastle upon Tyne
Place PublishedNewcastle upon Tyne
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