You are getting your versions muddled up.
You are describing attributes of the NeXT-based OS X but calling it MacOS 9.
MacOS 9 was the final version of Classic. No preemption, weak virtual memory, weak cooperative multitasking, no virtual machines for anything.
MacOS 9 is the OS that ran inside the Blue Box on Mac OS X for backwards compatibility.
> You are describing attributes of the NeXT-based OS X but calling it MacOS 9.
You're mistaken.
> MacOS 9 [had] no preemption
Classic Mac OS has had vertical retrace (VBL) interrupts since System 1.0 (which are a form of preemption). But suppose we disregard that.
>> MacOS 9 had a preemptively scheduled kernel.
The GP is correct. Applications run cooperatively within the Blue task, but the Blue task itself runs preemptively with other MP tasks (which an application can create).
loading story #50315222