> So while trying the latest Kega, which is awesome btw, I found a "disable SRAM"
> function, and it made the copy-protection code fail. Hooray ! But still there
> are many unanswered questions here...

My guess: the games tries to write to SRAM. Impossible on an original cart with no SRAM (=> original game, go ahead), possible with copiers that simulated SRAM in some way to allow SRAM games to save (=> lock the game). And easy, free protection mechanism, as long as copiers cannot turn off SRAM saving.