DMV11 Synchronous Controller Technical Manual

This technical manual, "DMV11 Synchronous Controller Technical Manual," provides comprehensive information about the DMV11, an intelligent communications synchronous line controller developed by Digital Equipment Corporation.

The document details the following key aspects:

1. Introduction and Overview: It describes the DMV11 as a high-performance device designed for efficient, high-speed (up to 56K b/s) synchronous communications in distributed networks, supporting both point-to-point and multipoint configurations. A core feature is its reliance on the Digital Data Communications Message Protocol (DDCMP), with the DMV11's microcode handling all DDCMP processing. It highlights features like support for 12 tributaries, down-line loading, diagnostic testing, and modem control.

2. System Operation and Programming:

   • Command/Response Structure: The DMV11 interacts with the host CPU (LSI-11) through 16-bit Control and Status Registers (CSRs). User programs issue various input commands (microprocessor control/maintenance, mode definition, control, buffer management) and receive output responses (buffer disposition, control, information) to manage data transfers and report conditions.
   • Microcode Operation: The internal microcode is central to the DMV11's functionality, implementing a dynamic polling algorithm for multipoint networks, extensive error recording, and managing internal data structures like Tributary Status Slots (TSS) and Global Status Slots (GSS) for network and station-specific parameters.
   • Programming Techniques: The manual covers detailed procedures for DMV11 start-up, specifying user-defined parameters for polling and communication link behavior, accessing error counters, error recovery procedures, and methods for booting remote stations.

3. Technical Description: It outlines the hardware architecture, centered around a 6502 microprocessor, supported by ROM and RAM. It details interfaces to the LSI-11 bus (including NPR circuitry for DMA transfers and interrupt control) and the external world via a USYRT (Universal Synchronous Receiver/Transmitter) and modem interfaces (RS-232-C, RS-423-A, CCITT V.35, integral modem).

4. Installation and Service:

   • Installation: Provides step-by-step instructions for unpacking, pre-installation considerations (such as network topology, system requirements, device/vector address assignment), physical installation into the LSI-11 bus, and initial testing.
   • Maintenance & Troubleshooting: Emphasizes Field Replaceable Unit (FRU) isolation (module or cable). It describes troubleshooting techniques for multipoint environments, utilizing a comprehensive set of error counters (data link, station, threshold) to diagnose faults. It also covers various diagnostic programs (static logic tests, functional diagnostics, Data Communications Link Test Program - DCLT) for verifying the controller's operation and isolating problems.

Appendices offer supplementary details on DDCMP, floating device and vector addresses, and modem control register formats.