Sorgelig wrote:Amiga spoiled by many versions of CPUs, so if game developer wanted his game to run on different Amigas, then he couldn't relay on CPU performance as A500 has 68000, A1200 has 68020, A4000 has 68040. And it's not included different accelerators.
Yes, I know. But the Amiga 1200 was released at the 90's. Plenty of games were released before the A1200 existed. And even then, it is very possible that some titles have internally two versions, one for the 68000 and other for the 020. Yes, they are the minority of course, and probably only original releases.
Protection can relay on many other factors not related to CPU performance. Usually protections relay on disk specific format.
Protections have two goals. One is to make you difficult to copy the software. That could be at the media or could be something from the packaging (manual, codewheel, etc). But the other goal is also to make you difficult to crack it. For this purpose protections use all sort of obfuscating and encryption techniques, sometimes depending on undocumented features, etc. It is here that many times compatibility breaks.