I always felt that on the Lisp Machine one of the great things are the Lisp-like interfaces into the system. For a lot of stuff there is for example very little

I always felt that on the Lisp Machine one of the great things are the Lisp-like interfaces into the system. For a lot of stuff there is for example very little manual memory management necessary and the whole thing is very introspective at runtime - due to a very object-oriented architecture. The operating system runs most of the time in a way, that would be beyond a typical debug mode on conventional machines: all data is tagged, almost all data is an instance of some class, all basic functions are type checked and bounds checked at runtime, all function calls are on the stack and many functions have (optional) named arguments. A developer would also run the whole OS with full cross references, documentation references and source references. Then there are selective ways to run some code with higher debug features, like source locators for local variables/functions or using the Lisp interpreter for some code - usually code would run compiled, but the interpreter would support things like source stepping and seeing macro expansions.