Random DCA Test

Summary

This document provides the technical specification and assembly code for the "Random DCA Test" (MAINDEC-8E-D6GC-D), a diagnostic program designed for the PDP-8/E computer.

Key functions include:

• Purpose: To test the functionality of the Deposit Accumulator (DCA) instruction by storing random operands into various memory locations and verifying the results.
• Operation: The program selects random memory locations and operands to test the DCA instruction. It performs a cycle where it deposits an operand, reads the location back, and compares it against the expected value.
• Error Reporting: If the contents of a memory location do not match the expected operand, the program prints an error message to a connected teletype, detailing the address of the DCA instruction, the target address, the operand, the actual contents of the location, and an error indicator.
• User Controls: The program utilizes the computer's switch register (SR) to manage execution modes, such as bypassing error printouts, holding specific "from" or "operand" constants, or selecting specific addresses for testing.
• Diagnostic Scope: It is designed to run in memory locations 0400 through 7600, using the last memory page for the binary loader. A full cycle consists of 3,904 tests, after which the teletype rings a bell.