PDP-9 TTY Test

This document describes the PDP-9 TTY Test, a diagnostic program designed to verify the operational status of a KSR 33 or KSR 35 Teletype and its associated control logic.

The program is divided into two main parts:

1. Part 1 (Teleprinter Tests): Focuses on the teleprinter control logic, testing the complete character set, carriage return, line feed, space, right-hand margins, and mechanical worst-case scenarios. It includes tests for setting and clearing teleprinter flags and interrupt handling.
2. Part 2 (Keyboard Tests): Evaluates the keyboard input control logic, character input/output, and the ability to process keyboard input without losing data during teleprinter operations.

The program requires a standard PDP-9 computer equipped with either a Model 33 or 35 KSR Teletype and 4510 words of core memory. Loading is done via paper tape in HRI mode.

Users interact with the program by setting ADDRESS SWITCHES and pressing I/O RESET and START. Various console switches (ACS) allow for special operating modes, such as:

• Looping tests: To run tests continuously, especially for stability checks with marginal power supply voltages.
• 'Scope mode: For detailed diagnostic observation of control logic.
• Variable printing speed control: For the mechanical worst-case test.
• Specific test configurations: For line length, line feeds, and character pairs.
• Keyboard buffer content print-out: For debugging input buffer shifts.
• Character simulation: To test specific character inputs.

The document includes detailed starting procedures, operational switch settings for each test, and descriptions of error halts. Error recovery involves pressing CONTINUE to re-execute a failed test, with an option to enter 'scope mode for deeper analysis. A key restriction is that external devices causing interrupts should be turned off during operation.