A unified facility for interprocess communication and processor dispatching on the Intel 432 is described.The facility is based on a queuing and binding mechanism called a port.The goals and motivations for ports, both abstract and implementation views of them, and their absolute and comparative performance are described.

This paper describes interprocess communication and process dispatching on the Intel 432. The primary assets of the facility are its generality and its usefulness in a wide range of applications. The conceptual model, supporting mechanisms, available interfaces, current implementations, and absolute and comparative performance are described.

The Intel iAPX 432 is an object-based microcomputer which, together with its operating system iMAX, provides a multiprocessor computer system designed around the ideas of data abstraction. iMAX is implemented in Ada and provides, through its interface and facilities, an Ada view of the 432 system. Of paramount concern in this system is the uniformity of approach among the architecture, the operating system, and the language. Some interesting aspects of both the external and internal views of iMAX are discussed to illustrate this uniform approach.

The extent to which resource allocation policies are entrusted to user-level software determines in large part the degree of flexibility present in an operating system. In Hydra the determination to separate mechanism and policy is established as a basic design principle and is implemented by the construction of a kernel composed (almost) entirely of mechanisms. This paper presents three such mechanisms (scheduling, paging, protection) and examines how external policies which manipulate them may be constructed. It is shown that the policy decisions which remain embedded in the kernel exist for the sole purpose of arbitrating conflicting requests for physical resources, and then only to the extent of guaranteeing fairness.