VR14, VR20 Display Test

This document contains the diagnostic program manual and source code for the "VR14, VR20 Display Test." Created in August 1971, this diagnostic program is designed to test the PDP-12 display system by generating a series of visual test patterns on a VR20 scope.

Key aspects of the document include:

• Purpose: It verifies the display unit's performance, including channel selection, character display, and power supply regulation.
• Operating Procedure: The program is loaded into memory, and operators can use specific switch settings to freeze individual test patterns for calibration or adjustment of the display's deflection amplifiers.
• Test Patterns: The diagnostic includes subroutines to generate horizontal and vertical grid lines, specific character sets, and an "X" pattern to adjust gain controls.
• Technical Details: The bulk of the document consists of the assembly source code (written for the PDP-12/PDP-12B), including memory maps, cross-reference symbol tables, and logic routines for controlling the display patterns.