Towards the Formal Specification of the Requirements and Design of a Processor Interface Unit

ion PIU-Environment Clock-Level Behavior PIU-Environment Clock-Level Structure PIU Clock Level 1_ Composition Environment Clock Level Figure 2.1: Example PIU Specification Hierarchy Using Clock-Level Composition. Figure 2.2 describes a competing approach where abstraction is performed within the subsystems themselves, before composition. The abstract PIU specification in this case describes the PIU's behavior with respect to its outputs in addition to its internal state. PIU-Environment Transaction-Level Behavior