I suspect that there's a design document somewhere that has secrets and tips. Plus MacOS and NeXTstep have been ported so many times that by now any arch-level things are well-isolated. A lot of the pain of MacOS on x86 were related to kernel extensions and driver API changes. And a lot of stuff fell out during the 64-bit transition.
In general, MacOS/iOS/iPadOS owe everything to the excellent architecture laid down by the NeXT team back in the day. NeXTstep now has the dream that MS tried and failed to do back in the day: an OS that runs on every kind of device they make. Funny how that is.
In general, MacOS/iOS/iPadOS owe everything to the excellent architecture laid down by the NeXT team back in the day. NeXTstep now has the dream that MS tried and failed to do back in the day: an OS that runs on every kind of device they make. Funny how that is.