Report Number: CS-TR-75-501
Institution: Stanford University, Department of Computer Science
Title: Procedural events as software interrupts.
Author: Pettersen, Odd
Date: June 1975
Abstract: The paper deals with procedural events, providing a basis for synchronization and scheduling, particularly applied on real-time program systems of multiple parallel activities ("multi-task"). There is a great need for convenient scheduling mechanisms for minicomputer systems as used in process control, but so far mechanisms somewhat similar to those proposed here are found only in PL/I among the generally known high-level languages. PL/I, however, is not very common on computers of this size. Also, the mechanisms in PL/I seem more restricted, as campared to those proposed here. A new type of boolean program variable, the EVENTMARK, is proposed. Eventmarks represent events of any kind that may occur within a computational process and are believed to give very efficient and convenient activation and scheduling of program modules in a real-time system. An eventmark is declared similar to a procedure, and the proposed feature could easily be amended as an extension to existing languages, as well as incorporated in future language designs.