KA655 CPU System Maintenance

This document is the "KA655 CPU System Maintenance" guide, published by Digital Equipment Corporation in March 1989. It is intended for Digital Field Service personnel and qualified self-maintenance customers.

The guide provides comprehensive information on the KA655 central processing unit (CPU) and systems containing it, covering:

• System Overview: Description of the KA655 CPU and MS650-BA memory subsystem, including its features, components (like CVAX chip, CFPA60, CMCTL, SSC, CQBIC), connectors, and the H3600-SA CPU I/O panel.
• Configuration: Guidelines for system and module configuration, including module order rules, DSSI (Digital Storage System Interconnect) setup (cabling, dual-host capability, node IDs, unit numbers, allocation classes), and power/bus load calculations.
• Firmware: Detailed explanation of the KA655's resident firmware, covering halt entry/exit, power-up sequence, bootstrap process, and an interactive console I/O mode with commands for system examination, modification, and control (e.g., BOOT, CONFIGURE, DEPOSIT, EXAMINE, HELP, INITIALIZE, MOVE, NEXT, REPEAT, SEARCH, SET, SHOW, START, TEST, UNJAM, X-binary load/unload).
• Troubleshooting and Diagnostics: Procedures for diagnosing system problems using KA655 ROM-based diagnostics, including power-up self-tests, diagnostic scripts, console displays, system halt messages, console error messages, VMB (Virtual Memory Bootstrap) error messages, and loopback tests. It also offers specific troubleshooting suggestions for isolating memory failures and issues with RF-series Integrated Storage Elements (ISEs).
• Appendices: Detailed instructions on configuring the KFQSA storage adapter (for DSSI devices), KA655 CPU address assignments, and a list of related documentation.