Example transmission system simulations are used to illustrate criteria for quality architecture: Component interoperability, re-usability, reliability and maintainability. Top-level architectural issues such as system partition, encapsulation of components and a Graphical User Interface that is decoupled from the core software are considered. It is suggested that component communication should be: Write a file, signal a “commit” and then read by the recipient. This protocol allows input and output data types and ranges to be checked. An error code on failure allows roll-back to a previously saved state whereas a successful completion signal can be used as a sequential control The desirable feature of very loosely coupled independent components implies insensitivity to construction technology. This allows the use of legacy and commercial software packages. In addition, components can be deployed on different types and scales of networks and can be fixed on computers and data transferred to them, or vice-versa.