A formal model of several fundamental VHDL concepts

This paper presents a formal model of several fundamental concepts in VHDL including the semantics of individual concurrent statements, and groups of those statements, resolution functions, delta delays, and hierarchical component structuring. Based on this model, several extensions to VHDL are proposed including nondeterministic assignments and unbounded asynchrony. Nondeterminism allows the specification of environments and of classes of devices. This model naturally captures the meaning of composition of VHDL programs.<
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