KA681/KA691/KA692/ KA694 CPU System Maintenance

This document, "KA681/KA691/KA692/KA694 CPU System Maintenance," is a comprehensive technical guide published by Digital Equipment Corporation in August 1994. It is intended for Digital Equipment Corporation service personnel and qualified self-maintenance customers, detailing the procedures and tests required to maintain and troubleshoot VAX 4000 Model 500A, 505A, 600A, 700A, and 705A systems which utilize these specific CPU kernels.

The manual is structured into several key areas:

1. System Maintenance Strategy: Outlines the overall approach to service delivery, product service tools and utilities (including OpenVMS error handling, ROM-Based Diagnostics, Firmware Console Commands, and loopback tests), and available information services and field feedback mechanisms.
2. CPU System Overview: Provides a detailed description of the system's hardware components, including the KA681-KA694 CPU modules (highlighting their Q22-bus and DSSI bus features), MS690 memory modules, optional DSSI daughter boards, and the BA440 enclosure components (console module, system control panel, backplane, power supply, and fans).
3. System Setup and Configuration: Guides users through the physical and logical setup of the system. This includes proper module order for CPU, memory, and Q-Bus options, configuring internal mass storage devices, planning for system expansion using various expanders, and setting up DSSI VAXcluster configurations with their specific rules (e.g., node IDs, termination, grounding). A significant portion covers the use of firmware commands (CONFIGURE, SHOW, SET HOST/DUP) to examine and modify system and DSSI device parameters (such as allocation class, unit numbers, node names, and hardware write-protection).
4. System Initialization and Acceptance Testing: Describes the normal operational flow, including power-up sequences, Power-On Self-Tests (POST), and ROM-based diagnostics. It outlines acceptance test procedures for the CPU, memory, DSSI, and Q-Bus components, details the machine state after power-up, and explains the operating system bootstrap process (including disk, tape, and MOP Ethernet bootstrapping).
5. System Troubleshooting and Diagnostics: Offers a robust methodology for identifying and resolving system problems. It covers interpreting OpenVMS error logs using ANALYZE/ERROR to diagnose CPU, memory, system bus, and DMA-related faults. The chapter also details the use of Symptom-Directed Diagnosis (SDD) tools like VAXsimPLUS and System-Initiated Call Logging (SICL), and provides instructions for running internal DSSI drive tests (DRVTST, DRVEXR) and various loopback tests.
6. FEPROM Firmware Update: Explains the process for updating the CPU's firmware, including necessary preparatory steps, methods for updating via Ethernet or tape, and interpreting associated error messages.

The document also includes extensive appendices serving as technical references for firmware commands, address assignments, ROM and NVRAM partitioning, data structures, and a comprehensive list of error messages.