Standard bus for 8-bit microprocessor systems

A large application area of microprocessor systems, where low cost is essential and relatively low throughout can be tolerated, is serviced by simple 8-bit systems. Examples of such applications are industrial process control, program development systems and intelligent instrumentation. A bus definition which adequately covers the requirements of this application area is currently being investigated for standardization by the IEEE Computer Society's P961 working group, and is known to the industry as the STD bus. There are already a number of 8-bit schemes in use, particularly in Europe, but most do not have the potential for use as a standard as they are defined in such as way that they are specific to one family of CPU only. The STD bus will support any 8-bit CPU and has already evolved as a de facto standard for small card systems in the US, being supported by around 60 manufacturers to date. Its popularity in Europe is restricted only by its nonconformance with IEC mechanical specifications (Eurocard) and its use of direct edge connectors rather than the more reliable DIN 41612 connector. However a recent move to provide a European format STD bus had been made and is highlighted later in this paper