FORTRAN IV-PLUS Object Time System

This document provides a comprehensive technical reference for the FORTRAN IV-PLUS Object Time System (OTS), which is a library of assembly language modules that complement compiled FORTRAN IV-PLUS programs. It covers:

• OTS Architecture: Explains the five main components of the system (I/O processing, mathematical functions, compiled-code support, error processing, and impure storage).
• Standards & Conventions: Defines the calling sequences (R5, PC, R4, F0), register usage, and data formats for interfacing with the OTS.
• Data Base: Details the program sections (PSECTs), work areas, and structure of the Logical Unit Device Table (FFDB) and Array Descriptor Blocks (ADBs).
• I/O Processing: Describes the internal mechanisms for I/O operations, including initialization, record processing, and the use of File Control Services (FCS).
• Error Handling: Details how the OTS detects and processes run-time errors using trap instructions and error control bytes.
• System Generation: Explains how to tailor the OTS during installation using assembly-time options and macros.