Linking Loader Utility Program

This document describes the operation and use of the Linking Loader Utility Program for the PDP-15 computer. The Linking Loader is designed to load and link both relocatable and absolute binary program units, which are typically generated by the FORTRAN IV Compiler or MACRO-15 Assembler. It functions within the DOS-15, ADVANCED, and Background/Foreground Monitor Systems.

The manual outlines how the loader processes machine language instruction codes and special "loader codes" to relocate, link, and assign COMMON data storage areas. It explains the loading process, starting with explicitly named program units, followed by automatic loading and linking of I/O handlers and library subprograms from user and system libraries. The loader resolves global linkages and manages memory allocation, preventing program units from crossing 4K page or 8K bank boundaries. Optionally, it can load symbols and their definitions into a program dictionary for debugging with DDT.

The document also details the structure of program units, library files, and the identification codes used by the loader to interpret data words. Operating procedures include .DAT slot assignments, different commands to call the loader (LOAD, GLOAD, DDT, DDTNS), and command string syntax with options for memory map output (program names, global symbols, COMMON blocks). Finally, it lists and explains various error conditions that may occur during the loading process.