The FORTRAN II source language [1, 2] places rather severe restrictions on the form a subscript may take, primarily because of the manner in which indices are incremented in iterative loops. In the process of constructing a compiler for a medium-sized (8008-word memory) computer which will accept the FORTRAN II source language, it became clear that the “recursive address calculation” scheme, as used in the FORTRAN compilers to minimize object-program running time, was probably not the best one to use. This system, described in some detail by Samelson and Bauer [3], requires that the subscript expression be a linear function of the subscripting variable. The alternative, which requires complete evaluation of the “storage mapping function”, is usually rejected because of the time required for the object program to perform the necessary address calculation.
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