[en] Until recently, digital control systems have been implemented on centralized processing systems to function in one of several ways: (1) as a single processor control system; (2) as a supervisor at the top of a hierarchical network of multiple processors; or (3) in a client-server mode. Each of these architectures uses a very different set of communication protocols. The latter two architectures also belong to the category of distributed control systems. Distributed control systems can have a central focus, as in the cases just cited, or be quite decentralized in a loosely coupled, shared responsibility arrangement. This last architecture is analogous to autonomous hosts on a local area network. Each of the architectures identified above will have a different set of architecture-associated issues to be addressed in the verification and validation activities during software development. This paper summarizes results of efforts to identify, describe, contrast, and compare these issues