Pdp-8 Instruction Test Part 2B

Summary

This document provides the technical specifications, operating instructions, and source code listing for the "PDP-8 Instruction Test Part 2B" diagnostic program. Created on January 12, 1968, this software is designed to verify the correct operation of the PDP-8 processor’s two's complement addition (TAD) and rotation logic (RAL, RTL, RAR, RTR).

Key features include:

• Functionality: The program uses pseudo-random numbers to test the addition and rotate logic. It detects errors by comparing results against expected values and can provide diagnostic printouts on a keyboard printer to help pinpoint the source of a hardware failure.
• Requirements: The program requires a PDP-8 processor and must be run after a successful completion of "Instruction Test 2A."
• Operation: Users can control the test through the console's SWITCH REGISTER. Specific switch settings allow for different modes, such as stopping on an error, entering a "scope mode" to repeat a failing loop, or triggering error printouts.
• Diagnostics: If an error is detected during the TAD or rotate tests, the program halts and displays the relevant register contents, which can then be cross-referenced with the provided program logic to troubleshoot the hardware.
• Program Listing: The document includes a full assembly language listing and a symbol table to assist with maintenance and debugging of the diagnostic routine itself.