Operational specification is a method of documenting specifications for systems which separates the implementation details from the problem requirements details. Operational specification permits simulation of the specification enabling the specification creator to test the specification to see how well it satisfies prescribed functional requirements. The line between specification and description when applied to computer architecture design is rather thin in my opinion and the experience of this author indicates that a particular specification tool known as PAISLey (described in more detail below) can serve as a suitable hardware description tool.
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