They can copyright certain sequence of bits though, like console makers did a while ago to enforce licensing (e.g. can't boot this rom without these sequence of bits, but this sequence of bits is actually a nintendo logo which cannot be distributed unless you have nintendo's permission).
A crack does not compile anything, but even if you go that road, it will be argued anyway that the patch which is applied is copyrighted.
Now, of course, it's another thing to prove that the patch may indeed be copyrighted...