T89 Cartridge Converter
The T89 cartridge converter is a 60 to 72 pin adapter that allows NES owners to plug a 60-pin Famicom game into a 72-pin-based NES. The cartridge required the user to have the Famicom cartridge label to face the back as otherwise it would cause damage to the cart and/or system. There is a fabric tab on the convert to allow the easy removal of the convert from the original front-loading NES and the subsequent top loader (although the cartridge was easy to access, the converter would sit in the cartridge slot of the second model in a near flush like state, thus leaving the adaptor difficult to remove).
History
The original Nintendo console released in Japan (the Famicom) used a 60-pin cartridge for games. When Nintendo decided to market it outside Japan, they redesigned a number of things, including changing the cartridge system to a 72 pin setup. This is problematic for anyone wishing to play Japanese games on a NES, and thus a number of companies (including Nintendo themselves) produced an adapter to allow 60-pin games to be played in 72-pin systems.
Trivia
Due to a production overrun of the two R.O.B. games (Gyromite and Stack-Up) in Japan, Nintendo ended up selling these two games in the U.S. with an internal adapter. The game itself looks normal, but inside are the electronics from the Japanese version plugged into a 60 to 72 adapter. This has contributed to a shortage of the two games, with people looking for a cheap adaptor disassembling these games. Only the early editions have the adapters. The same adapter is also in early editions of the following games:
1942, Clu Clu Land, Donkey Kong Jr., Duck Hunt, Elevator Action, Excitebike, Golf, Gumshoe, Gyromite, Hogan's Alley, Mike Tyson's Punch-Out!!, Pinball, Raid on Bungeling Bay, Rygar, Soccer, Stack Up (all have converters), Tennis, Urban Champion, Wizards and Warriors, Wrecking Crew, although this is less publicly known.