DECsystem10 FORTRAN Programmer's Reference Manual

This document is the FORTRAN Programmer's Reference Manual for the DECsystem-10, published in January 1977. It serves as a comprehensive guide for programmers using the FORTRAN-10 compiler (Version 5) and its associated software components on the DECsystem-10.

The manual is divided into two main parts and several appendices:

• Part I: Introduction to Using FORTRAN-10 with SOS This section provides a practical, step-by-step guide for new or learning FORTRAN programmers on the DECsystem-10. It covers the fundamental interactions with the operating system's SOS editor, including:

  • Logging in and out of the system.
  • Typing, entering, running, and storing FORTRAN programs.
  • Editing programs using SOS commands (inserting, deleting, replacing lines, renumbering).
  • Basic FORTRAN-10 input and output operations (READ, WRITE, ACCEPT, TYPE, and managing data files).
  • Other helpful system commands (TYPE, DIRECT, DELETE, RENAME, and seeking assistance).

• Part II: FORTRAN-10 Language Manual This part is intended as a reference for experienced FORTRAN programmers and details the FORTRAN language as implemented by the FORTRAN-10 Language Processing System. It covers:

  • Language Elements: Character set, line structure, data types (integer, real, double-precision, complex, octal, literal, statement label, logical), constants, symbolic names, variables, and arrays (subscripts, dimensioning).
  • Expressions: Arithmetic and logical expressions, including rules for writing and evaluation hierarchy.
  • Statements:
    • Compilation Control: PROGRAM, INCLUDE, END statements.
    • Specification: DIMENSION, TYPE, IMPLICIT, COMMON, EQUIVALENCE, EXTERNAL, PARAMETER statements.
    • Data and Assignment: DATA, Arithmetic Assignment, Logical Assignment, and ASSIGN statements.
    • Control: GO TO (unconditional, computed, assigned), IF (arithmetic, logical, two-branch), DO, CONTINUE, STOP, and PAUSE statements (including TRACE option).
    • Input/Output (I/O): Detailed explanations of data transfer operations, transfer modes (sequential, random access, append), I/O statement keywords (READ, WRITE, REREAD, ACCEPT, PRINT, PUNCH, TYPE, FIND, ENCODE, DECODE), logical unit numbers, and FORMAT statement references and descriptors.
    • NAMELIST: Defining and using NAMELIST I/O lists.
    • File Control: OPEN and CLOSE statements, specifying file access, disposition, and other parameters.
    • Device Control: REWIND, UNLOAD, BACKSPACE, ENDFILE, SKIPRECORD, SKIPFILE, and BACKFILE statements.
  • Subprograms: Statement functions, intrinsic functions, external functions, subroutines, RETURN statements (including multiple returns), and multiple subprogram entry points (ENTRY statement).
  • Block Data Subprograms: For initializing common areas.

• Appendices Offer more specialized and advanced information, including:

  • The ASCII-1968 character code set.
  • In-depth guidance on using the FORTRAN-10 compiler, including available switches, compiler-generated variables, and error reporting.
  • Recommendations for writing efficient user programs, including optimization techniques and considerations for interaction with non-FORTRAN programs (e.g., COBOL-10) and mixed-compiler environments.
  • A detailed description of the FORTRAN-10 Object Time System (FOROTS) and the FORTRAN-10 Debugging Program (FORDDT), covering their features, commands, calling sequences, and error messages.
  • Information on the FORTRAN-10 Realtime Software (FORRTF) and its subroutines.

The document highlights FORTRAN-10 extensions and additions to the 1966 ANSI standard by printing them with gray shading, enabling users to distinguish between standard and DEC-specific features.