System control structure of the IBM eServer z900

As computer systems become more complex, the use of embedded controllers for initializing and maintaining system operation is becoming increasingly prevalent. In the IBM eServer z900, a new control approach was introduced. This paper discusses why its introduction was necessary and outlines its associated, key technological and economic innovations. In particular, the following topics are addressed: service subsystem topology, hardware elements for performing system control, hardware abstraction, object-oriented framework for control, and inter-networking of system control microprocessors.