> What he means by cost? [...] a well designed memory protection system wont be
> noticeable to the use performance wise.

I think that copying the contents of a memory area is always slower than just passing a pointer.

>> For MorphOS to keep backward compability a true bigendian mode is required.

> For backwards compatibility you use an emulator.

Yes, that's what's done in MorphOS (and OS4). And for such transparent emulation you need a matching byte order, as Zylesea correctly points out.