VAX 11/780 Diagnostic System Technical Description

This document, the "VAX-11/780 Diagnostic System Technical Description," provides a comprehensive overview of the VAX-11/780 computer system's diagnostic capabilities. Published in February 1979, it is intended for field service personnel, offering detailed information for error detection, fault isolation, troubleshooting, and repair.

The diagnostic system is described as a hierarchical set of software components, ranging from general system functional tests to dedicated microprogram techniques, organized into several levels (Console Level, Levels 1, 2, 2R, 3, 4). These diagnostics can operate in various environments:

• Console Environment (Standalone): Uses the LSI-11 microcomputer console system for basic system control, examining/depositing data, and running microdiagnostics or standalone macrodiagnostics.
• Cluster/System Environment (Standalone): Runs macrodiagnostic programs (Levels 3 and 4) which require exclusive use of the VAX-11/780 CPU and often direct I/O access.
• User Environment (Under VMS): Runs diagnostic programs (Levels 1, 2, 2R) under the VMS operating system, potentially sharing the system with other user programs.

Key aspects covered include:

• Console Diagnostics: ROM-resident tests, console command language for system control (Boot, Clear, Continue, Deposit, Examine, Halt, Start, Link, Repeat, etc.), and communication with console floppy disks and remote terminals.
• Microdiagnostic Programs: Low-level diagnostics designed for module isolation of logic failures within the CPU, floating-point accelerator, and MOS memory controllers. They include "Hardcore Tests" for basic CPU elements and "Microtests" for more complex CPU functions, cache, and SBI.
• Diagnostic Supervisor (Macrodiagnostics): A software framework that supports higher-level macrodiagnostic programs, managing their loading, sequencing, and execution. It provides common services like operator interaction, error message formatting, and memory management.
• Macrodiagnostic Programs (CPU Cluster Exerciser Package, RH780 (MBA) Diagnostic, DW780 (UBA) Diagnostic, Peripheral Diagnostics): Detailed descriptions of programs that test specific hardware components like the CPU cluster (CPU, Unibus/Massbus adapters, memory), Massbus Adapter, Unibus Adapter, and various peripheral devices (e.g., disk reliability).
• Error Reporting and Troubleshooting: Extensive descriptions of error message formats, their interpretation, and how to correlate them with program listings for effective fault isolation. The document also includes a glossary of diagnostic software terms.