VT100 and PDT-11 Video Terminals Maintenance

This document serves as a self-paced/lab course for the maintenance of VT100 and PDT-11 video terminals, focusing on their introduction, physical/functional description, and Field Replaceable Units (FRUs). The VT100, developed by Digital Equipment Corporation, is introduced as a modular, field-upgradable, and easily serviceable ASCII alpha-numeric video display terminal.

The course describes the terminal's main components, including the Power Supply, DC Power Harness, Terminal Controller PCB (which manages data flow between the keyboard, host computer, and CRT), Video Monitor PCB, Flyback Transformer, CRT Monitor Assembly, Keyboard PCB, Speaker, and Keyboard Cable. Key features of the VT100 include flexible display formats (80 columns by 24 lines or 132 columns by 14 lines), standard US and UK character sets with limited graphics, 7x9 dot matrix characters, selectable white-on-dark or dark-on-white displays, blinking underline or block cursors, and various highlighting options (underline, reverse video, blink, bold). It also supports double-height and double-width characters, jump and smooth scrolling, and full-duplex serial asynchronous communication across a broad range of baud rates (50 to 19,200). The terminal incorporates internal power-up diagnostics and stores settings in non-volatile memory. Optional features like the Advanced Video Option (AVO) for extended display capabilities and the 20mA Current Loop Communication Option are also covered.