FORTRAN II Programming Manual PDP-7

This document serves as a programming manual for the FORTRAN II system on the PDP-7 computer, designed for machines with 8K of memory, primarily using paper tape. It aims to guide scientists and engineers in writing PDP-7 FORTRAN II programs by detailing the language's structure and operational procedures.

The manual is divided into two main sections:

1. FORTRAN II Language Description: This section covers fundamental aspects of FORTRAN II, including:

   • Introduction to the Language: Explains FORTRAN II as a problem-oriented compiler that converts input into executable machine language.
   • Arithmetic and Data-Specification Statements: Describes arithmetic expressions, their evaluation, the use of the replacement (equals) sign, and how numbers are represented and stored (integers and real numbers in fixed-point, and two-word or three-word floating-point modes). It also details data allocation for arrays using DIMENSION statements.
   • Program Control: Outlines statements that manage the flow of a program, such as GOTO for unconditional branching, IF statements for conditional branching, DO loops for iterative procedures, CONTINUE as a dummy statement, and STOP/PAUSE for program termination.
   • Input/Output (I/O) Statements: Explains how data is transferred between core memory and external devices like keyboards, paper tape readers/punches, magnetic tape, and DECtape. It covers I/O assignments, data lists, and various format specifications (E, F, I, X, H, A) for numeric and non-numeric data, as well as data organization into records.
   • Subprograms: Functions and Subroutines: Discusses user-defined functions (FUNCTION, RETURN statements) and subroutines (CALL statement, COMMON storage for data sharing), along with an introduction to machine language coding within FORTRAN and subprogram linking.

2. Operating Procedures, Diagnostics, and Error Messages: This section provides practical guidance on using the PDP-7 FORTRAN system, including:

   • Operating Procedures: Step-by-step instructions for compiling FORTRAN programs, assembling them, and loading them onto a paper-tape system.
   • Diagnostics and Error Messages: Lists and explains error codes generated during compilation (compiler diagnostics) and assembly (FORTRAN Assembler error messages) to help programmers debug their code.

The appendices include character code equivalences (ASCII, 'A' Format, 'H' Format), information on using extended memory, and a summary description of the FORTRAN language elements. The manual assumes familiarity with general FORTRAN II programming principles.