@Nefilim
020 or higher? You're talking above me now 
I'm not too familiar with the tech aspects of the Amiga yet... I just bought one again, after being without it for ten years or so...
Parts of OS3.5 & 3.9 are optimisied for processors >68000 and won't run on a stock A500/A600/A2000/A1000. The installer scripts on both later OSs check for a 68020 or greater (030/040/060) processor.
I have managed to load OS3.9 onto my oldest A1000, but It has had some serious hardware hacking done to it and has a 14Mhz 68020 inside.
