Type 348 Display Test For PDP-4/7

This document describes a test program for the Type 34 Cathode Ray Tube (CRT) display, designed to assist operators in maintaining and aligning the display system. Running on a PDP-4/7 computer, the program allows operators to select and display a variety of visual patterns using the switch register, generally without needing to restart.

Key patterns and their diagnostic uses include:

• Basic Lines: Vertical, horizontal, and diagonal lines, useful for checking raster position, symmetry, and decoder network operation.
• Axial Point Plotter: Allows plotting individual points on either the X or Y axis, controlled by switch register bits for precise coordinate selection.
• Segmented Sweep Patterns: Horizontal and vertical sweeps that divide the CRT into nine overlapping segments. These are crucial for diagnosing phosphor coating uniformity (identifying burnt-out spots), detecting AC ripple (indicated by wavy lines), and checking for decoder network deficiencies (uneven trace spacing).
• Light Pen Pattern: Displays the letter "P" to test the functionality of the Light Pen; successful detection causes the display to complete to "PEN."

The program requires initial calibration of the display controls, such as vertical and horizontal sensitivity, focus, and intensity, to ensure the patterns accurately fill the CRT reticle. It also outlines loading procedures using the RIM Loader, details error halts (e.g., for Light Pen flag issues), and provides instructions for error recovery. The comprehensive set of patterns and diagnostics aims to provide a robust tool for evaluating the display's performance.