Originally Posted by itix
It is not 100% compatible. It looks like they are going to patch all software they run on that board.
I have read that they patch binaries at run time before they start. It works well enough for 1 Atari compiler but not the other which generates many instructions that need patching. This type of patching would never be 100% on the Amiga because it is difficult to identify small amounts of data as code or data. It's also time consuming on startup. It looks like it's not possible to only trap instructions on the fly. Some problems would be rems/remu using the same encoding as divsl/divul and byte/word sized stack writes being padded to 4 byte alignment (68k is 2 byte alignment).
I think the Natami team made the right choice in going the fpga enhanced 68k with ColdFire route. The ColdFire has some useful additional instructions that increase speed and code density. The ColdFire dropped some powerful 68k instructions and addressing modes that hurt code density. A 68k plus ColdFire CPU will be more powerful than 68k or ColdFire alone with the best code density in the industry while allowing the majority of 68k and ColdFire programs to be used.