SYSTEMS PROGRAMMING WITH JSP: EXAMPLE--A VDU CONTROLLER.

The article presents a discussion on systems programming with Jackson Structured Programming (JSP). In JSP and Jackson Structured Design (JSD), a computer program or process always models a data stream or a process in the outside world. Since most external processes and data are conveniently described as regular expressions with sequences, selections, and iterations, which are also the classical program structuring elements, this is indeed possible. In the article, the basic principles of JSP and JSD have been illustrated by means of an embedded micro-program controlling a video display unit. JSP represents a systematic method for designing a correct and efficient program from the elements of any language. The JSP designer starts by analyzing the relevant data streams. When their structures have been found, the fundamental similarity between data and programs is applied. In this way, the program becomes a model of its data. JSD applies the same idea to entire systems; it encompasses the steps from a preliminary system concept to functioning programs.