Hello,

> ok, i want to get OS9 onto this mac for testing/flashing purposes.
> 
> i've got a spare 2G scsi disk sitting here on my desk to put it on.
> never having installed MacOS (any version) in my life, what do i need
> to do to make this happily co-exist with netbsd?  
If each has its own disk - nothing. Just have the bootvars utility under MacOS if you want to avoid setting all the OF variables by hand every time you use MacOS.

> can i make the os9
> disk scsi id#1 and /AAPL,ROM will be able to boot from that? 
Yes. I use a similar configuration, only the MacOS disk hangs on a different controller.

> (with of course having to fix OF before expecting netbsd to boot again, but i'm
> getting quite good at that *G*)
Use bootvars, save a config file and booting to NetBSD from MacOS will be just a doubleclick :)

> my primary concern is i don't want to hork netbsd.
MacOS will ignore the disk if there are no MacOS volumes on it, and you can always disable it in Drive Setup.

have fun
Michael