Pearl at the age of five: Case study of development and application of a common high order realtime programming language

The Programming language PEARL for industrial process automation has been developed since 1969. After extensive studies its final definition was frozen in 1976. Since then considerable experience has been gained with some 25 implementations and 200 applications.With PEARL at the age of three, these experiences are offered as a case study in this paper.The paper starts with a characterization of PEARL by indicating the requirements for such a tool, by classifying it with respect to other language types and by pleading for embedded realtime features. As PEARL has been submitted to ISO for international standardization, the question of how it meets the requirements set up by ISO is more thoroughly answered in Appendix A.The report of experience is given separately for implementation, application, and standardization with as much quantitative results as possible, including compiler behaviour, application areas, and economical benefit.For readers not yet familiar with PEARL a tutorial introduction by means of a simple but completely programmed control problem is given in Appendix B.