Au contraire mon ami...
OS9 onwards had Preemptive multitasking.
Now, if you'd said Amiga was the first to have preemptive multitasking, you'd have been correct.
I'm afraid you're incorrect again. MultiFinder, released in 1988, allowed cooperative multitasking. Also, no version of Apple's "classic" OS (all Mac OS's prior to OS X) allowed preemptive multitasking. A sloppy threading capability was tacked onto, I think it was, Mac OS 8 - but it was not an ideal model.
Although, and most are unaware of this, the operating system of the Apple Lisa (which predated the Macintosh) offered cooperative multitasking and protected memory. It was based on a 5MHz 68000 -- all before the Mac existed on the market.
blakespot