Guide to VAX-11/780 System Troubleshooting

This document, "Guide to VAX-11/780 System Troubleshooting," is an internal manual for D.E.C. Field Service Engineers, published in November 1985. Its primary purpose is to provide a structured approach and reference material for troubleshooting problems encountered with VAX-11/780 systems.

The guide emphasizes a systematic troubleshooting methodology, starting from defining the problem and making educated guesses, through setting up and conducting test cases, to evaluating results and refining definitions. It stresses the critical importance of maintaining a comprehensive system log book and gathering all available error information, including hardware register dumps, software dumps, console terminal outputs, and error log reports.

The document categorizes VAX-11/780 problems into various types, such as Operating System crashes (including Machine Checks and Double Error Halts), system hangs, booting issues, and problems related to specific devices or power. It provides detailed sections on troubleshooting these different problem areas, often referencing specific VAX registers (like ID registers, NEXUS registers) and their bit definitions for diagnosis.

Key resources and tools highlighted include:

• Console commands: CONSOL.SYS for interacting with the system at a low level.
• Special command files: DUMP. (for hardware register dumps after crashes), HANG. (for dumps and single-stepping to diagnose hung loops), and SDA.COM (for analyzing software dumps).
• Diagnostic programs: EVSBA.EXE (Autosizer) and SPEAR (Performance Error Analysis and Reporting).
• Physical checks: Guidance on testing voltages, power monitoring signals, and environmental factors like heat, cooling, and vibration.
• Human resources: Encouragement to leverage fellow workers, remote support (RDC), and local support groups.

The manual is organized into eight sections, covering the troubleshooting outline, VMS operating system information, special command files/programs, VAX architecture basics, bus descriptions, UNIX error reporting (a placeholder for future release), miscellaneous information, and detailed definitions of NEXUS register bits. It also contains extensive charts for address breakdown and register interpretations.