1. A system for representing a hardware device in a physical environment, wherein said hardware device has inputs and said physical environment imposes restrictions on said inputs, the system comprising: a Mealy machine representation of said hardware device, said Mealy machine having inputs corresponding to said hardware device inputs and said Mealy machine implementing a set of state transition functions for manipulating input bits and state bits; a first store for holding a set of state bits for said Mealy machine; a second store for holding a set of input bits for said Mealy machine; an input device for inputting a set of initial states of said state bits into said first store; means for implementing a set of state transition functions for manipulating said input bits and said state bits; and means for providing input bits to said second store, said input bits satisfying a set of constraints representing said restrictions by the physical environment, wherein said means for providing input bits comprises means for providing unconstrained bits and means for constraining said unconstrained bits whereby said set of constraints is satisfied, wherein said means for constraining comprises means for transforming said set of constraints into a set of correction conditions and means for applying said correction conditions to said unconstrained bits.