FORTRAN IV Advanced Software System Programmer's Reference Manual

This manual describes the FORTRAN IV language and its compiler system for the PDP-9 computer, providing essential information for writing, compiling, and executing FORTRAN programs within the PDP-9 Advanced Software System.

The document is organized into three main parts:

1. Basic FORTRAN IV Language: This section details the fundamental elements of the FORTRAN IV language, including constants (integer, real, double-precision, logical, Hollerith), variables, arrays and subscripts, and expressions (arithmetic, relational, logical). It also covers various statement types: arithmetic, control (GO TO, IF, DO, CONTINUE, PAUSE, STOP, END), input/output (READ, WRITE, FORMAT, BACKSPACE, REWIND, ENDFILE), and specification (TYPE, DIMENSION, COMMON, EQUIVALENCE, EXTERNAL, DATA).
2. FORTRAN IV Object Time System (OTS): This part describes the collection of subprograms responsible for processing compiled FORTRAN IV statements during program execution. It outlines routines for formatted and unformatted I/O operations, auxiliary I/O statements (like BACKSPACE, REWIND, ENDFILE), computed GO TO, STOP, PAUSE, and file commands.
3. PDP-9 Science Library: This section provides detailed descriptions of the mathematical routines available in the library, categorizing them as intrinsic functions (e.g., absolute value, truncation, remaindering, float, fix), external functions (e.g., exponential, logarithms, trigonometric, square root, arctangent, hyperbolic tangent), and sub-functions. It also covers the arithmetic package for integer, real, and double-precision arithmetic, including details on accumulators and calling sequences.

The manual notes that PDP-9 FORTRAN IV largely conforms to the USASI Standard FORTRAN (X3.9-1966), with specific exceptions outlined to accommodate the compiler's operation within limited core storage, such as the exclusion of complex arithmetic, fixed array sizes in subprograms, and blank COMMON being treated as named COMMON. It also discusses two compiler versions (F4 and F4A) and provides guidance on linking FORTRAN IV programs with MACRO-9 subprograms and library routines, along with a comprehensive list of error codes.