DHT80 Option Installation Guide

This document is the DHT80 Option Installation Manual for the Digital Equipment Corporation DECsystem 5100, published in September 1991.

It serves as a guide primarily for Digital service representatives and qualified self-maintenance customers to install and test the DHT80 Asynchronous Communications option.

The DHT80 option expands the DECsystem 5100's serial connectivity by adding eight asynchronous lines: seven DEC-423 lines with MMJ-type connectors and one RS-232 port with full modem control.

The manual provides comprehensive instructions covering:

• Installation Procedures: Detailed, step-by-step guidance on shutting down the system, removing system covers and internal drive shelves, adding necessary standoffs and internal cables, physically installing the DHT80 module, and reassembling the system. It also includes steps for replacing an existing DHT80 option.
• Testing and Diagnostics: Instructions for verifying that the system recognizes the installed DHT80 option (using commands like printenv iooption and conf -f), and performing internal and external mode diagnostic tests for all asynchronous lines, including those on the system module and the new DHT80 lines, often requiring specific loopback devices.
• Field-Replaceable Units (FRUs): An appendix listing all components and cables associated with the DHT80 option, along with their part numbers.

The document emphasizes safety precautions (e.g., grounding for electrostatic discharge) and notes that installation and troubleshooting should only be performed by qualified personnel.