VAX-11 PATCH Utility Reference Manual

This document is the VAX-11 PATCH Utility Reference Manual, published in March 1980 for VAX/VMS V02. It serves as a comprehensive guide for experienced system programmers on using the VAX-11 Image File Patch Utility (PATCH).

PATCH enables direct examination and modification of executable, shareable, and device-driver image files without requiring recompilation, reassembly, or relinking of source code. It automatically creates a journal file to record all changes and attempted modifications. Notably, the manual explicitly states PATCH is not intended for customer use on Digital Equipment Corporation's own software, and applying unauthorized revisions may invalidate warranties.

The manual details:

• How to invoke and terminate PATCH sessions (interactive or batch via command procedures).
• The various input and output files involved (input image file, output image file, journal file, command procedures).
• The use of symbolic referencing to locate and define memory addresses, including details on PATCH's symbol table and pathnames.
• The concept and application of "patch areas" for storing additional code or data.
• Controlling the environment for commands and output through "entry and display modes" (e.g., context, length, radix, symbol search).
• The syntax rules for entering PATCH commands, including special operators for arithmetic expressions and addressing locations.
• Detailed descriptions of all PATCH commands (e.g., ALIGN, CHECK ECO, CREATE, DEFINE, DELETE, DEPOSIT, EVALUATE, EXAMINE, EXIT, INSERT, REPLACE, SET ECO, SET MODE, SET MODULE, SET PATCH AREA, SET SCOPE, SHOW MODE, SHOW MODULE, SHOW PATCH AREA, SHOW SCOPE, UPDATE, VERIFY).
• A summary of error messages produced by the utility.