> it could have been worthy to port AmigaOS to x86
No, it could not, and this is why:
AmigaOS is sometimes called a microkernel, but it's not really, inasmuch as one of the biggest problems in microkernels is efficient communications between the kernel (in supervisor mode, i.e. x86 ring 0) and the servers running in user space (x86 ring 2 or 3 depending on OS).
AmigaOS did not have that. It ran on a 68000 and everything was in the same, flat, shared memory space. This makes inter-process comms easy, but it also has a cost: a rogue program can trample all over other processes' memory, including the kernel's memory.
Thus bringing down your system, the famous Amiga "guru meditation".
You can't do this on an 80286 because it doesn't have a flat memory space, even in Protect Mode. You need an 80386 running in 32-bit mode: what we now call x86-32.
But AmigaOS has that total absence of memory protection. You can implement that on a 386, no problem, but it makes your OS unstable. This is why a rogue NLM could bring down a Netware 3 or 4 server: a flat memory space.
This is why many alternative OSes of the late 1980s flopped: they couldn't use the memory-management hardware that appeared in the 386, and in Motorola's 68030 (in the 68020 it was an external MMU chip, IIRC.)
This is also why CBM couldn't take advantage of the MMU in the 68030 and 68040. If it rewrote AmigaOS to use the MMU, all the legacy code would have broken and failed to run, because the mechanism it used to communicate with the kernel would have gone away.
(This is aside from the issues of 68000 assembly code conversion and register starvation and all the other things others have brought up later in the comments, which are legitimate and valid.)
So, while it might have been technically feasible to port AmigaOS to the 386 -- I mean, today, AROS shows it's possible -- you'd inherit all the limitations of the original, but on much more expensive hardware.
This would make it un-competitive.
This is why OS/2 flailed and then failed. This is why Windows 3 evolved into Win9x but then had to die: it was replaced by a true 32-bit OS that used the MMU: Windows NT, derived from bits of Portable OS/2 and some of the design of DEC VAX VMX, because MS hired the lead programmer of VMS and his team.
It's why MacOS couldn't fully exploit the 68030 and 68040, and indeed, the PowerPC. It's also why Apple's Copland project failed. This stuff is really hard. Apple ended up moving to UNIX.
No, it could not, and this is why:
AmigaOS is sometimes called a microkernel, but it's not really, inasmuch as one of the biggest problems in microkernels is efficient communications between the kernel (in supervisor mode, i.e. x86 ring 0) and the servers running in user space (x86 ring 2 or 3 depending on OS).
AmigaOS did not have that. It ran on a 68000 and everything was in the same, flat, shared memory space. This makes inter-process comms easy, but it also has a cost: a rogue program can trample all over other processes' memory, including the kernel's memory.
Thus bringing down your system, the famous Amiga "guru meditation".
You can't do this on an 80286 because it doesn't have a flat memory space, even in Protect Mode. You need an 80386 running in 32-bit mode: what we now call x86-32.
But AmigaOS has that total absence of memory protection. You can implement that on a 386, no problem, but it makes your OS unstable. This is why a rogue NLM could bring down a Netware 3 or 4 server: a flat memory space.
This is why many alternative OSes of the late 1980s flopped: they couldn't use the memory-management hardware that appeared in the 386, and in Motorola's 68030 (in the 68020 it was an external MMU chip, IIRC.)
This is also why CBM couldn't take advantage of the MMU in the 68030 and 68040. If it rewrote AmigaOS to use the MMU, all the legacy code would have broken and failed to run, because the mechanism it used to communicate with the kernel would have gone away.
(This is aside from the issues of 68000 assembly code conversion and register starvation and all the other things others have brought up later in the comments, which are legitimate and valid.)
So, while it might have been technically feasible to port AmigaOS to the 386 -- I mean, today, AROS shows it's possible -- you'd inherit all the limitations of the original, but on much more expensive hardware.
This would make it un-competitive.
This is why OS/2 flailed and then failed. This is why Windows 3 evolved into Win9x but then had to die: it was replaced by a true 32-bit OS that used the MMU: Windows NT, derived from bits of Portable OS/2 and some of the design of DEC VAX VMX, because MS hired the lead programmer of VMS and his team.
It's why MacOS couldn't fully exploit the 68030 and 68040, and indeed, the PowerPC. It's also why Apple's Copland project failed. This stuff is really hard. Apple ended up moving to UNIX.