This paper describes a simulation study of a class of carrier sense multiaccess buses with collision detection, similar to the Xerox Ethernet. The driving loads for the network models are similar to ones that might be found in an office information system which integrates data and voice communication. Various backoff algorithms are considered, to investigate the suitability of the approach and to suggest an appropriate family of architectures for communication within this medium.

MERT is a multi-environment real-time operating system for the Digital Equipment PDP-11/45 and 11/70 computers. It is a structured operating system built on top of a kernel which provides the basic services such as memory management, process scheduling, and trap handling needed to build various operating system environments. Real-time response to processes is achieved by means of preemptive priority scheduling. The file system structure is optimized for real-time response. Processes are built as modular entities with data structures that are independent of all other processes. Interprocess communication is achieved by means of messages, event flags, shared segments, and shared files. Process ports are used for communication between unrelated processes.