The MMU was a sanity-saver even in DOS development using a DOS-extender like DOS4GW or CWSDPMI, where a crash could actually be debugged/output a stacktrace rat

The MMU was a sanity-saver even in DOS development using a DOS-extender like DOS4GW or CWSDPMI, where a crash could actually be debugged/output a stacktrace rather than instantly reboot the machine. A fair-few DOS applications (via DPMI) also implemented virtual memory schemes like a "real OS" - I remember POVRay 2.0 officially requiring 2 MB of RAM, but was able to start on my 1MB 386SX machine (albeit with 1-2 mins of HDD-thrashing...).