Re: Copy Protection Blues
Yes, a lot of Commodore 64 protection was done in a similar way. Make a straight disk copy, run a program to corrupt a specific sector which the loader then checked for and would bomb out if it didn't encounter it.
I once had some copy protection that used a bit psychological warfare on the user in that, at one point about 3 or 4 levels in, the entire program was ORed with a string of characters that read "THIS COPY PROTECTION IS 50 LEVELS DEEP" (or something similar). It wasn't actually that deep at all.