> OSX wasn't a rewrite of MacOS. It was a new chrome over top of NeXTStep In addition major new chrome (Cocoa, OS X Finder, etc.) Mac OS X originally included

> OSX wasn't a rewrite of MacOS. It was a new chrome over top of NeXTStep In addition major new chrome (Cocoa, OS X Finder, etc.) Mac OS X originally included a version of the older Mac OS APIs (Carbon) as well as a Mac OS 9 virtual environment (Classic) for running older non-Carbon apps. It was really a chimera that included pretty complete Mac OS 9 ABI support as well as a Mac-flavored version of NeXTSTEP. It's a bit of a shame that Apple keeps abandoning its backward compatibility layers (I hope Rosetta2 will be different) but I guess that's what emulators are for.