Game Boy is an 8-bit handheld video game device developed and manufactured by Nintendo. It was released in Japan on April 21, 1989, in North America in August 1989, and in Europe on September 28, 1990. It is the first handheld console in the Game Boy line, and was created by Gunpei Yokoi and Nintendo Research & Development.The Game Boy is Nintendo's second handheld system following the GameWatch series introduced in 1980, and it combined features from both the Nintendo Entertainment System and Game & Watch.It was originally bundled with the tetris game.The Game Boy and Game Boy Color combined have sold 118.69 million units worldwide.The Game Boy has five operation buttons labeled "A", "B", "SELECT", and "START", as well as a directional pad.There is a volume control dial on the right side of the console and a similar knob on the left side to adjust the contrast.At the top of the Game Boy, a sliding on-off switch and the slot for the Game Boy cartridges are located.Nintendo recommends users to leave a cartridge in the slot to prevent dust and dirt from entering the system.The Game Boy also contains optional input and/or output connectors. On the left side of the system is an external power supply jack that allows users to use an external rechargeable battery pack or AC adapter (sold separately) instead of four AA batteries.The Game Boy requires 6 V DC of at least 150 mA. A 3.5 mm stereo headphone jack is located on the bottom side of the console which allows users to listen to the audio with headphones or speakers.On the right side is a port that allows a user to connect to another Game Boy system via a link cable, provided both users are playing the same game.The port can also be used to connect a Game Boy Printer. The link cable was originally designed for players to play head-to-head two-player games such as in Tetris. However, game developer Satoshi Tajiri would later use the link cable technology as a method of communication and networking in the popular Pokémon video game series