DHU11 Interface User's Guide

This document is the DHU11 Interface User's Guide for an asynchronous multiplexer developed by Digital Equipment Corporation.

The guide describes the DHU11 module (M3105), which provides 16 full-duplex, asynchronous serial data channels for UNIBUS systems, suitable for data concentration, terminal interfacing, and cluster control.

Key features and capabilities highlighted include:

• High Throughput: A total module throughput of 15,000 characters per second, supported by a 256-entry FIFO for received characters and 64-byte FIFOs for output data on each channel.
• Flexible Data Transfer: Supports both Direct Memory Access (DMA) and programmed transfers.
• Programmable Communications: Allows for programmable data rates (50 to 38,400 bits/s) with split-speed per line, various character formats (5-8 bits, parity, 1, 1.5, or 2 stop bits), and automatic XON/XOFF flow control.
• Interface Compatibility: Complies with RS-232-C/V.24 and RS-423-A/V.10/X.26 standards, including full modem control for point-to-point or auto-answer dial-up operations.
• Onboard Intelligence & Diagnostics: Uses two 8051 microcomputers to handle data processing and reduce host overhead. It includes ROM-based self-tests and a background monitor program, with an LED indicator for GO/NO-GO status and detailed diagnostic information accessible via the receive FIFO.
• Configuration: Basic settings like I/O addresses, interrupt vectors, and priority are set via onboard switchpacks, while most other communication functions are programmable by the host system.

The manual is structured into four main chapters: Introduction (general description, specifications, interfaces), Installation (module configuration, cabling, testing), Programming (register definitions, programming features, examples), and Maintenance (internal and system diagnostics, troubleshooting, field replaceable units). It also includes appendices with a glossary and detailed information on modem control. The guide is primarily for DHU11 users, with installation and checkout details aimed at qualified Field Service personnel.