Pooley, RobWilliams, AlanBirtwistle, Graham2008-02-272008-02-271983-11-01http://hdl.handle.net/1880/45714This paper describes experiences with an implementation of the X25 long haul data communications protocol based on Demos, a Simula extension with enhanced discrete event capabilities. X25 has a modern definition with functionally separated layers which are mapped directly into a hierarchy of Simula (Demos) packages. During development and testing, the X25 processes were embedded in a simulation model of the real time environment, and subjected to extensive testing before acceptance. The design steps are repeated should further enhancements be required, or design errors be revealed after commissioning.EngComputer Scienceunknown1983-138-2710.11575/PRISM/30374