With the Super Nintendo, Nintendo assumed again the sole authority over game distribution. To enforce its policies, the company devised three layers of protection to prevent unauthorised cartridge distribution and circumvention of royalties.
Firstly, the external shape of cartridges is different between regions, so they won't fit on consoles from different areas. Be that as it may, this could be easily bypassed using a third-party adapter.
Secondly, like the NES, this console still incorporates the 10NES protection system to lock out unauthorised distributors. However, the CIC chip was eventually cloned.
As a final layer - specifically designed to combat bootlegging - games included a chain of piracy checks within their program, such as:
- SRAM size verifications: Bootleg cartridges often contain large SRAM blocks to accommodate various games.
- Code integrity checks: A series of checksums embedded throughout the game's code verify whether the previous SRAM size verification routines have been removed. These checks are dispersed at different stages of the game, making them difficult to locate and remove.
While these measures could be nullified by manually stripping out the routines, this was a time-consuming task. After all, they would be scattered around the game only to upset the player (and eventually make them buy a legitimate copy). Truth be told, you'll notice that most ROMs available online have had all their piracy checks removed.