VRL2 Display Test

This document is a technical manual and assembly source code for the "VRL2 Display Test," a diagnostic program designed for the PDP-12 and PDP-12B computer systems. Created on June 6, 1969, by Dave Ferrarini of the Diagnostics Group, the program is used to test the display system by generating three distinct patterns on the scope:

1. Character Pattern: Displays half-characters in different quadrants and sizes to verify display accuracy.
2. Glitch Pattern: Generates vertical and horizontal lines to test display positioning and integrity.
3. Diagonal Line Pattern: Displays a diagonal line from the bottom left to the top right of the screen.

The manual provides step-by-step loading and operating procedures, including specific console settings for the ASR teletype. It also includes the full assembly source code, detailing the subroutines responsible for generating each test pattern. The program includes features to cycle through these patterns, freeze the display on a specific pattern, or return to the monitor.