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

A sample program for the FORTRAN-20 compiler.

c2345+---^---------^---------^---------^---------^---------^---------^--........
      program hello                    ! The above line is a comment.
                                       ! Text from exclamation pt. to 
                                       !    end of line is a comment.
      write(5,*) ' Hello, World!'      ! 5 is the user TTY logical unit.
                                       ! Space before Hello is significant!

      stop                             ! The compiler ignores blank lines.
      end                              

The same program without annotation:

      program hello
      write(5,*) ' Hello, World!'
      stop
      end                              

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.

P. H. Hargrove, S. T. Whitlock, E. Boman. (1997, December). Fortran 77 Tutorial [Online]. Available: http://www.stanford.edu/class/me200c/tutorial_77.