DEC-10-ULKMA-B-D LINK-10 Ver 2 Jul4

This document is the DECsystem-10 LINK-10 Programmer's Reference Manual, published in July 1974. It serves as a comprehensive guide for intermediate-level applications programmers on the LINK-10 Linking Loader, a system utility program for the DECsystem-10 operating system.

LINK-10's primary function is to merge independently-translated object modules (.REL files) into a single executable program (core image). It handles relocation of code and data, resolves symbols (both internal and external), and manages libraries (system and user-defined) to satisfy undefined references. The output—the executable program—can be run immediately or saved for later use. LINK-10 also generates various auxiliary output files, such as map files, log files, symbol files, and expanded core image files, which are valuable for debugging.

The manual details two methods of using LINK-10:

1. Automatically: Through system commands like LOAD, EXECUTE, or DEBUG, which typically involve the COMPIL program for convenience.
2. Directly: By issuing the "R LINK" system command, which provides users with fine-grained control over the loading process, especially for large and complex programs.

A significant feature of LINK-10 is its overlay capability, which allows programs larger than available core memory to run by dynamically loading and replacing program segments as needed, structured in a tree-like hierarchy. Users can control this process and various loading parameters using an extensive set of switches.

The document is structured to cover:

• An introduction to LINK-10's capabilities and initialization.
• Detailed explanations of automatic and direct usage, including command formats and alphabetic descriptions of all LINK-10 switches (e.g., /CORE, /DEBUG, /OVERLAY, /SAVE, /SYSLIB) and their algorithms.
• Guidance on designing and implementing overlay structures.
• Practical examples of LINK-10 usage.
• Appendices covering LINK Item Types, the overlay handler, a general-purpose subroutine (FUNCT.), MIXFOR feature, and a list of LINK-10 messages.
• A glossary and an appendix aiding users in transitioning from the older LOADER program to LINK-10.