> Why it is hard for a mature company with legacy systems to create a new operating system is a difficult thing to explain In general, the hardest problem for

> Why it is hard for a mature company with legacy systems to create a new operating system is a difficult thing to explain In general, the hardest problem for such companies is backwards compatibility. In the case of Apple, it was doubly so: they tried to build a pre-emptive multitasking operating system with memory protection that was backwards compatible (both for applications and system extensions) with an existing OS that had cooperative multitasking, did not have memory protection, and had OS support for patching system calls (a feature that allowed third parties to develop of such things as Switcher (https://www.folklore.org/StoryView.py?project=Macintosh&story=Switcher.txt https://www.folklore.org/StoryView.py?project=Macintosh&stor...), After Dark, Adobe Font Manager, and RAM Doubler).