Konrad Zuse's Plankalkul: the first high-level, "non von Neumann" programming language

Abstract

Konrad Zuse was the first person in history to build a working digital computer, a fact that is still not generally acknowledged. Even less known is that in the years 1943-1945, Zuse developed a high-level programming model and, based on it, an algorithmic programming language called Plankalku/spl uml/l (Plan Calculus). The Plankalku/spl uml/l features binary data structure types, thus supporting a loop-free programming style for logical or relational problems. As a language for numerical applications, Plankalku/spl uml/l already had the essential features of a "von Neumann language", though at the level of an operator language. Consequently, the Plankalku/spl uml/l is in some aspects equivalent and in others more powerful than the von Neumann programming model that came to dominate programming for a long time. To find language concepts similar to those of the Plankalku/spl uml/l, one has to look at "non-von Neumann languages" such as APL or the relational algebra. This paper conveys the syntactic and semantic flavor of the Plankalku/spl uml/l, without presenting all its syntactic idiosyncrasies. Rather, it points out that the Plankalku/spl uml/l was not only the first high-level programming language but in some aspects conceptually ahead of the high-level languages that evolved a decade later.