Vr12 Display Test

This document describes the VR12 Display Test program for the PDP-12 computer. The purpose of this program is to test the PDP-12 display system by generating three distinct patterns on the scope: two using the DIS instruction and one using the DSC instruction.

Summary of Operations:

• Loading: The program uses a dial loader to load from locations 4000(8) to 6000(8).
• Execution: Upon starting, the program automatically cycles through the three display patterns, with each pattern displayed for approximately 10 seconds.

• User Controls:

  • Freeze: Striking the 'F' key allows the user to freeze the current display pattern.
  • Alternate: Striking any key other than 'F' directs the program to continue the automatic alternating sequence.
  • Reset: Setting switch 0 (SSW=0) returns the program to the dial loader.

• Pattern Details:

  • Pattern 1: Used for scope calibration.
  • Pattern 2: Generates patterns using the DSC instruction, displaying different characters in quadrants to test display logic.
  • Pattern 3: Displays an 'X' pattern using diagonal lines from corner to corner, used to adjust deflection amplifiers.

The document includes the complete assembly source code and a cross-reference table for the program labels.