TOPS-20 DDT Manual May85

This May 1985 manual, "TOPS-20 DDT Manual (AA-M273A-TM)," serves as both an introduction and a reference guide for TOPS-20 DDT (Dynamic Debugging Tool), specifically for debugging MACRO-20 programs. It assumes the reader is familiar with TOPS-20, MACRO-20 programming, and instruction formats.

The document covers fundamental debugging tasks such as loading DDT, basic command usage, starting and stopping program execution, setting breakpoints, examining and modifying memory, and single-stepping instructions. More advanced topics include DDT command syntax, expressions, various display modes, searching for data patterns, and manipulating program symbols.

It also explains how to use DDT's patching function to insert and test new instructions without reassembling the program. Specialized DDT variants are detailed: FILDDT (for disk files/structures and the running monitor), KDDT and MDDT (privileged modes for debugging the monitor), and EDDT (for executive mode programs). Commands for physical, virtual, and extended addressing are included to manage complex memory environments. An appendix on error messages and a glossary of key terms complete the manual.