Mac OS 9.x, based on Mac OS 8 was the final product based on the classic MacOS architecture. Like previous version, it lacks true protected memory or pre-emptive multitasking. MacOS 9 was abandoned in favor of of the Unix-ish NextStep/Openstep based Mac OS X.
| 1.x-6.x | 7.x | 8.x | 9.x | MacOS X | All |