Globally asynchronous systems of interactive Moore state machines

The problem of organising the temporal behaviour of globally asynchronous systems consisting of parallel interacting blocks is discussed. System blocks are represented by the Moore state machine model. The earlier suggested GALA (Globally Asynchronous, Locally Arbitrary) design methodology is used. This methodology is based on decomposing the system to a Processors Stratum (stratum of blocks) and a Synchronisation Stratum (synch-stratum). The synch-stratum acts as a distributed asynchronous clock network that produces local synch-signals for the processor stratum, which basically can be a synchronous prototype. The synch-stratum is a self-timed circuit that interacts with the processor stratum (system devices) via the handshake protocol. Every local device that has received the request signal from the synch-stratum produces the acknowledgment signal and sends it back. In this study, some logic circuits of universal modules are suggested. They provide an easy way to design any synch-stratum for parallel synchronisation of system blocks with arbitrary interconnection graphs and for wave synchronisation of system blocks with acyclic interconnection graph.