VAX-11/725 Diagnostic System Overview Manual

This document, the "VAX-11/725 Diagnostic System Overview Manual (EK-DS725-UG-001)," published in February 1984 by Digital Equipment Corporation, serves as a comprehensive guide for Field Service engineers and other technical personnel on using the VAX diagnostic system with the VAX-11/725 computer system.

The manual outlines the VAX-11/725 diagnostic system structure, which comprises six levels of diagnostic programs, from VMS-based operating system diagnostics to console-based microdiagnostics. It details a layered diagnostic strategy, with Customer Runnable Diagnostics (CRD) being central for system maintenance, offering both automated (AUTO) and interactive (MENU) testing modes.

Key areas covered include:

• Console Subsystem: Describes its functions, hardware (front panel controls, TU58 tape drives, remote access port), operating modes, and a command language for direct system interaction (e.g., BOOT, EXAMINE, DEPOSIT, LOAD, START, TEST).
• System Start Functions: Explains cold (BOOT) and warm (RESTART) start procedures, including power-up self-tests and the roles of primary and secondary bootstrap programs.
• Microdiagnostics: Details the lowest level of diagnostics (ENKBx, ENKCx) for testing console microprocessor and CPU microcode, and the Microdiagnostic Monitor (MICMON) used for their control and execution.
• Diagnostic Supervisor: Provides instructions on loading this supervisor via primary (disk) and secondary (TU58 tape) load paths, crucial for troubleshooting disk subsystem failures, and its associated commands.
• Level 4 Diagnostics: Focuses on the "hardcore instruction test" (EVKAA) and how to execute it and interpret errors.
• Diagnostic Area Maintenance: Explains procedures for building and updating the system disk's diagnostic area by copying files from distribution media using COPY commands or the Diagnostic Update Configuration Tool (DUCT).

The document aims to equip users with the knowledge and procedures necessary to effectively identify, isolate, and address hardware faults for repair.