PDP-6 Programming Manual DDT-6 Dynamic Debugging Technique

This document details DDT-6, the Dynamic Debugging Technique, an interactive on-line debugging system for the PDP-6 time-sharing computer. It is presented as a significant improvement over traditional debugging methods, offering dynamic program check-out and efficient utilization of computer and programmer time for multiple users.

DDT-6 provides comprehensive tools for examining and changing memory locations, using both symbolic and absolute addresses. Users can control how information is displayed (e.g., symbolic, octal, decimal, ASCII, floating point) and navigate through memory using various commands. The system features powerful program interrogation capabilities, including word, not-word, and effective address searches, and allows for the use of mask registers.

A core component is the breakpoint system, enabling users to set up to eight conditional or unconditional breakpoints, restart programs, and examine internal breakpoint registers. DDT-6 also supports symbolic program changes, allowing for insertions and deletions, and includes functions for defining and deleting symbols. Additionally, it offers commands for paper tape operations such as punching checksummed loaders and program blocks, reading from tape, and verifying data. The manual aims to equip users with the knowledge to efficiently and easily handle any debugging situation.