Random DCA Test

This document serves as the technical documentation for the "Random DCA Test" (MAINDEC-8E-08GC-D), a diagnostic program designed for the PDP-8/E computer. The program's primary purpose is to test the computer's DCA (Deposit Accumulator) instruction by generating random operand addresses and data values to verify that the operation is executed correctly.

Key aspects of the document include:

• Operating Requirements: The test requires a PDP-8/E with a teletype, and the program must be loaded using the standard binary loader into memory locations 0000 through 0407, with a test area spanning from 0410 to 7600.
• Control Settings: The program uses the Switch Register (SR) to control test parameters. Specifically, SR0 allows the operator to toggle between halting on errors or bypassing them, while SR2 through SR4 allow the user to hold specific values constant versus selecting them randomly.
• Error Reporting: If the program detects a failure, it performs an automatic scan of the test area and prints a diagnostic report. This report includes the location of the DCA instruction, the target address, the operand deposited, the actual location where the error occurred, and the contents found at that location.
• Diagnostic Features: The program includes "Scope Mode" capabilities, allowing technicians to isolate specific errors by re-running the test with defined, constant conditions.
• System Feedback: The teletype bell rings upon completion of seven passes (27,328 random tests), providing audible confirmation of the diagnostic cycle's status.

The final pages of the document provide the assembly code listing (PAL10) required to execute the test.