Apparatus and method for alterable resource partitioning enforcement in a data processing system having central processing units using different operating systems

In a data processing system having a plurality of non-homogeneous central processing units, apparatus is disclosed that permits a central processing unit not having mechanisms for protection of the allocation of resources to be coupled to the data processing system while preserving a peer relationship among the central processing units. The protection apparatus is interposed between the coupled central processing unit and the system bus and reviews each access to data processing system resources to insure that the accessed system resource is available to the associated data processing system. In addition, the apparatus permits initialization procedures without interprocessor conflict, provides status information from the coupled central processing unit to a requesting central processing unit and permits selected control signals to be applied to the coupled central processing unit.