Portable Operating Systems for Network Computers: Distributed Operating Systems Support for Group Communications

摘要

The project 'Portable Operating Systems for Network Computers' that ran from April 1982 until August 1985 saw the creation of an entire distributed operating system (MICROS/SAM2S) for a multiple ethernet system of DEC LSI-11 and Motorola 68000 systems. The modularity, hidden type managers, abstract manager hierarchies, message-oriented drivers, and layered tasks used in the design of the SAM2S operating system allowed the easy porting of the original LSI-11 based system to Motorola 68000 processors and its extension to a plexus of four interconnected thernets. The system was used to explore ways to support efficient communications within groups of processes scattered over many computers, especially in very large networks. This project has carefully delineated different classes of multicast communications within networks and has shown three different efficient waqys to implement multicast: host, channel, and tree-based protocols. Only tree multicast is suitably efficient for networks of thousands of computers.