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FORTRAN-20 is a FORTRAN compiler for TOPS-20. It supports the FORTRAN-77 standard (ANSI X3.9-1978 American National Standard Programming Language FORTRAN) with extensions and additions.
The purpose of this tutorial is to document the peculiarities of using FORTRAN-20 on TOPS-20 as opposed to other FORTRAN implementations on other operating systems; to highlight useful FORTRAN-20 extensions and additions that are not found in standard FORTRAN-77; and to briefly introduce the FORTRAN-77 programming language for those unfamiliar with it.
The order of presentation moves from more to less specialized and technical which runs counter to traditional organization, but the author feels this order is more convenient for the primary audience of programmers already familiar with FORTRAN but unfamiliar with the TOPS-20 operating system environment.
This section gives an brief overview of the FORTRAN-77 programming language for programmers with at least some experience with one or more other programming languages. It is not intended to be a comprehensive description or tutorial. Readers desiring a more complete introduction to Fortran are recommended to read the Fortran 77 Tutorial linked in the References section below.
A sample program for the FORTRAN-20 compiler.
program hello write(5,*) ' Hello, World!' stop end
(Text on each line is preceded by six spaces.)
Digital Equipment Corporation. (1987, February). AA-N383B-TK FORTRAN Language Manual [Online]. Available: http://bitsavers.trailing-edge.com/pdf/dec/pdp10/TOPS20/fortran/AA-N383B-TK_FORTRAN_Language_Manual_Ver_10_May85.pdf.