ZUSE,KONRAD PLANKALKUL - THE FIRST HIGH-LEVEL, NON VON-NEUMANN PROGRAMMING LANGUAGE

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 prog ramming model and, based on it, an algorithmic programming language ca lled Plankalkul (plan calculus). The Plankalkul features binary data s tructure types, thus supporting a loop-free programming style for logi cal or relational problems. As a language for numerical applications, the Plankalkul already had the essential features of a ''von Neumann l anguage,'' though at the level of an operator language. Consequently, the Plankalkul is in some aspects equivalent and in others more powerf ul than the von Neumann programming model that came to dominate progra mming for a long time. To find language concepts similar to those of t he Plankalkul, one has to look at ''non von Neumann languages'' such a s APL or the relational algebra. This paper conveys the syntactic and semantic flavor of the Plankalkul, without intending to present all it s syntactic idiosyncrasies. Rather, it tries to point out that the Pla nkalkul was not only the first high-level programming language but in some aspects conceptually ahead of the high-level languages that evolv ed a decade later.