> they could likely decompile MacOS classic and rework it to give it modern memory protection, virtual memory, preemptive multitasking, and networking.
It had most if not all of that.
It had networking from the start with AppleTalk, later Ethernet and internet with MacTCP.
MacOS 9 had a preemptively scheduled kernel.
The problem is having that and supporting the software ecosystem, which depended on cooperative scheduling without having memory protection.
MacOS 9 ‘solved’ that by running the classic OS in a single process. It had APIs for creating preemptively scheduled threads, but those threads were limited in what they could do.
It had most if not all of that.
It had networking from the start with AppleTalk, later Ethernet and internet with MacTCP.
MacOS 9 had a preemptively scheduled kernel.
The problem is having that and supporting the software ecosystem, which depended on cooperative scheduling without having memory protection.
MacOS 9 ‘solved’ that by running the classic OS in a single process. It had APIs for creating preemptively scheduled threads, but those threads were limited in what they could do.