SNES:Region Information
All Super Nintendo and Super Famicom consoles share the same cartridge connector and pinout, a change from the original NES where Japan used 60-pin cartridges and the rest of the world used 72-pin cartridges (disregarding pirated consoles). Though the general form factor of the cartridges is similar between regions, Nintendo used two different cartridge shapes depending on region, and certain region carts will not physically fit into different consoles. As with the NES, Nintendo also made use of a lockout system that consisted of two chips, one acting as a "lock" (console side) and another as the "key" (cartridge side). However, Nintendo greatly simplified the lockout system and only used two different chips; this is in contrast to the NES where Nintendo used several different chips and wound up splitting Europe in two incompatible regions. All NTSC consoles have the F411 lockout chip while all PAL consoles use the F413 chip.
The Super Nintendo hardware can be best divided into three regions; Japan/Korea, North America/Brazil, and PAL.
Japan and Korea (F411)
Both Japan and South Korea use a rounded cartridge shape and the F411 lockout chip. Cartridges from these regions do not fit in a North American SNES console due to tabs inside that console's cartridge port, which stop the game from being fully inserted. Conversely, North American cartridges do not fit inside Japanese or Korean consoles as they are too large to fit in their cartridge slots. A cartridge adapter is the most simple way to circumvent this, but there have been cases where people have extensively trimmed the top shell of their Super Famicom so US carts will fit.
PAL cartridges will fit perfectly but their different lockout chip prevents them from booting. Some PAL games can also detect if they are running on a console set to 60 Hz and will not play. Using a cartridge adapter, modifying the console with a SuperCIC board or fitting it with region switches (one to switch on/off the lockout chip, one to switch between 50 and 60 Hz video output) will allow for the play of PAL games on Japanese or Korean consoles.
North America and Brazil (F411)
The Super Famicom received a significant cosmetic redesign when it was brought over to North America; in addition to receiving a new name, the console shell was changed to a more rectangular design and many of these new design cues also extended to the cartridges. These new cartridges are slightly larger and blockier than their international counterparts, and so they will only fit properly in North American consoles.
Both Japanese and PAL cartridges do not fit due to the aforementioned cartridge slot tabs, but these can be easily defeated by simply cutting them out. Once these tabs are removed, there is nothing stopping Japanese or Korean cartridges from playing on a US console as they all use the same lockout chip. Simple cartridge adapters are also available for people who do not want to modify their consoles, but many of these adapters do not include the extra cartridge contacts needed for games which use expansion chips. Replacement cartridge slot inserts without the tabs are also available for those who are willing to modify their console without irreversibly modifying original parts.
PAL games will still not boot because of the different lockout chip, but this too can be rectified by a cartridge adapter, SuperCIC or region switch modifications.
Brazil received the same cartridge and console designs as North America, so all of the above information also applies to those consoles. The only difference with Brazilian consoles is that they output PAL-M video instead of NTSC, but this is irrelevant to how cartridges work on these consoles.
PAL (F413)
When the SNES was rolled out in PAL regions during 1992, Nintendo of Europe opted to keep the original Super Famicom design as opposed to using the US redesign. PAL cartridges use the same shells as Japanese cartridges, but Japanese games will not work in a PAL SNES because of the lockout chip. As with the Super Famicom, US games do not fit because of their different shape and will also encounter the same lockout chip issue as Japanese games.
Because the US and Japan received a number of games which never saw a European release (i.e. EarthBound, Chrono Trigger), cartridge adapters were available so these games would be playable on PAL consoles. These adapters worked by having two cartridge slots; the import cartridge would be inserted at the top while a PAL cartridge would be connected at the rear, basically riding "piggyback" onto the adapter. The adapter then used the PAL cartridge's lockout chip to "spoof" the console into playing the import game. PAL consoles can also be modified for region switches or a SuperCIC, though an adapter or top shell trimming will still be needed for US carts.