Programming in VAX FORTRAN (Ver 4.0)

This document, "Programming in VAX FORTRAN" (AA-D034D-TE, September 1984, Software Version: V4.0) by Digital Equipment Corporation, serves as a comprehensive manual for developing VAX FORTRAN programs on the VAX/VMS V4 system. It is intended for programmers and students with a basic understanding of FORTRAN.

The manual is structured into four main sections:

1. Using the VAX/VMS Operating System (Chapters 1-4): This section provides foundational knowledge for program development within the VAX/VMS environment. It covers essential system commands (like EDIT, FORTRAN, LINK, RUN), user interaction with the system (logging in/out, managing passwords, setting terminal types), DCL (Digital Command Language) usage including command procedures and symbol definitions, file management (file specifications, wildcards, directories, logical names, and file operations like copy, delete, rename, search, print), and an overview of the compilation, linking, and execution process for FORTRAN programs, including basic error handling.

2. VAX FORTRAN Language Specification (Chapters 5-13): This forms the core of the manual, offering a complete description of the VAX FORTRAN language, based on ANSI FORTRAN-77 with detailed VAX-specific extensions. Key topics include:

   • The fundamental elements of FORTRAN source programs (program units, statements, symbolic names, character set, and source code formatting rules).
   • Detailed explanations of data types (integer, real, complex, logical, character, Hollerith), data items (constants, variables, arrays, character substrings, and records), and expressions (arithmetic, character, relational, and logical, including operators and precedence).
   • Comprehensive coverage of all statement types, such as assignment statements, various specification statements (e.g., BLOCK DATA, COMMON, DATA, DIMENSION, EQUIVALENCE, IMPLICIT, INTRINSIC, NAMELIST, PARAMETER, PROGRAM, RECORD, SAVE, Structure Declaration, VOLATILE), and control statements (e.g., CALL, DO, IF, GO TO, PAUSE, RETURN, STOP).
   • An in-depth guide to subprograms (user-written and intrinsic functions/subroutines), focusing on argument passing mechanisms and entry points.
   • Extensive details on Input/Output (I/O) operations, including file specifications, logical unit numbers, different file organizations (sequential, relative, indexed), record formats, access modes, and various READ, WRITE, REWRITE, ACCEPT, TYPE, and PRINT statements, along with the intricacies of FORMAT statements and auxiliary I/O statements (OPEN, CLOSE, INQUIRE, REWIND, BACKSPACE, ENDFILE, DELETE, UNLOCK).

3. VAX FORTRAN Extensions and Advanced Topics (Chapters 14-18): This part delves into more advanced features and practical applications, specifically focusing on VAX FORTRAN extensions:

   • The use of structures and records for grouping associated data, including their definition, memory arrangement, and referencing.
   • Working with indexed files, covering creation, writing, reading, updating, and deleting records, and handling associated exception conditions.
   • Detailed information on manipulating character data, including substrings and character library functions.
   • A guide to debugging VAX FORTRAN programs using the VAX Symbolic Debugger, explaining its environment, commands (e.g., SET BREAK, SET WATCH, EXAMINE, DEPOSIT), and techniques for controlling program execution and inspecting data.
   • A discussion of error processing by the Run-Time Library, including default behaviors and how to use ERR, END, and IOSTAT specifiers for explicit error handling.

4. Appendices (Appendices A-E): These appendices provide supplementary reference information, such as additional language elements for compatibility with older FORTRAN versions, character sets supported by VAX FORTRAN (ASCII, Radix-50), detailed VAX FORTRAN data representation in memory, a comprehensive language summary of all operators and statements, and a listing of compiler and run-time diagnostic messages.