You're thinking of the debugger - the default Microbug that was built-in was pretty much only useful for printing or writing memory (or typing G FINDER into it,

You're thinking of the debugger - the default Microbug that was built-in was pretty much only useful for printing or writing memory (or typing G FINDER into it, causing the front app to crash and bringing you back to the Finder if the app was hung). Macsbug[0] which was an optional install was much more feature-rich, but it was still just a debugger and not actually a command line environment. [0]https://en.wikipedia.org/wiki/MacsBug https://en.wikipedia.org/wiki/MacsBug