How to find your Macs model and age? - Apple Community For PowerPC Macs, Mac OS X 10 4 11 and earlier offer Classic compatibility, and on certain 2003 and earlier Macs dual booting on Mac OS X 10 5 Mac OS 9: Mac models capable of dual-booting into 1… - Apple Community No Mac may run an older version of Mac OS 9 than was prebundled with it