Abstract
This paper describes the design of a modular operating system
for a network message processor. The basic requirements of the message
processor are defined by the University of Calgary's Distributed
Communication System (DCS), which is a general purpose network
connecting a variety of interactive terminals, two host computers, and a
trans-Canada network (DATPAC). Starting with these requirements, the operating system
is decomposed into a small set of easily understood components whose
interactions are both restricted and simple. A brief outline is then
presented of the implementation of these components in Oasis, an
extension of Simula 67 which was designed for implementing and
simulating system software. Finally, it is conjectured that: (1) A new, more
flexible, reliable system can be easily developed from this Oasis version, and (2)
the effort required to implement and test both the Oasis simulated version
and the actual system will be much less than that required for the original
operating system development.
