“I thought of actual living organisms moving back and forth across the cable,” Satoshi Tajiri told TIME in 1999. “But everyone was using it to compete. The idea I had was for information to go back and forth.” The cable was the Game Boy’s: a lead that plugged two machines together so that their programs could talk. Nintendo sold it as a way to play Tetris against a friend, each on your own screen. Tajiri’s Game Freak turned it into the reason Pokémon came on two cartridges.
The Game Boy was not alone. Atari’s Lynx linked up to eight machines through a port it called ComLynx, and Sega sold a Gear-to-Gear Cable for the Game Gear. The Game Boy’s cable is the one that lasted.
Fast facts
- Game Boy: in the American box from 1989 as the “Video Link Cable”; “Game Link” by 1991. British packs included a “two player lead”.
- Four players: the Game Boy Four-Player Adapter, sold with F-1 Race, was in Nintendo Power by January 1991.
- Speed: about 1,000 bytes a second on the original Game Boy’s own clock; the Lynx’s ComLynx could run at up to 62.5 kilobaud, “around 7K a second”.
- What made it essential: Pokémon Red and Green (Japan, February 1996), Red and Blue in America from September 1998.
Two screens, two views
In America the cable came in the box. “The Game Boy system comes complete with stereo headphones, a Video Link Cable and a great new version of the Soviet strategy game, Tetris,” Nintendo Power told readers in the autumn of 1989. Its launch pitch was that two linked machines gave each player a screen of their own, which a shared television could not: “Tennis, for example, is always seen from an individual player’s own side of the court and, in Baseball, the pitcher has a view from the mound and the batter has a view from the plate.” Games that supported it carried a “Video Link Symbol”.
Tetris was the demonstration, and its two-player game was a fight: “To win is to outlast your competitor. One important strategy is to transfer lines from your Game Boy to your opponent’s. For every two line completion of yours, one line will move over to your opponent. With a three line completion, two lines will transfer. With a Tetris, four lines will move over.”
British readers heard about the link before they could buy the machine. Computer and Video Games in April 1990 listed it as the Game Boy’s biggest advance over earlier LCD handhelds: “most exciting of all, was the ability to link two Gameboys together for simultaneous two player action”. When the Game Boy arrived that September, the lead was in the pack; a 1991 mail-order advert listed “Gameboy, Tetris, batteries, stereo headphones, two player lead”.
Four players
Two machines were not the limit for long. Nintendo Power answered the obvious question in June 1991: “When we announced the introduction of new four-player games for Game Boy, it left a lot of players asking, ‘How in the world do you connect four Game Boys?’ The answer: Our new Four-Player Adapter.” It came packed with F-1 Race. The other launch game was Super R.C. Pro-Am, “Programmed by England’s Rare Ltd.”, the studio the Stamper brothers of Ultimate had founded in 1985. The magazine’s Game Boy reviews started marking games “GL” for two linked players and “GL-4” for up to four, and its reader poll asked “How often do you use Game Boy to Game Link with other players?”
How the Game Boy link works
Nintendo’s programming manual describes a very small piece of hardware. The Game Boy’s serial port has one 8-bit data register, SB, and a control register, SC. A program puts a byte in SB and starts a transfer. On each pulse of the shift clock one bit leaves from the top of the register and one bit from the other machine arrives at the bottom, so “sending and receiving occur simultaneously”: after eight pulses the two machines have swapped bytes, and an interrupt can tell the program it is done.
Only one machine drives the clock. The other waits for it, with its byte ready, so the two programs have to agree which is which before they start. On the original Game Boy the internal clock is fixed at 8 kHz, about a millisecond per byte, or roughly 1,000 bytes a second. A game has to fit everything it needs to share into that: the lines a Tetris player has cleared, a racing car’s position, or a Pokémon’s details during a trade. The manual also notes a practical snag: the later Game Boy Pocket and Game Boy Color used a different plug, so linking one to an original Game Boy needed a conversion connector.
ComLynx and Gear-to-Gear
Atari’s Lynx, which reached American shops for Christmas 1989, was designed for more players. R.J. Mical, one of its designers, told The Games Machine that “you can easily connect up to 8 players through the system — each seeing his/her own perspective on the game.” RAZE explained that ComLynx, “called RedEye by Atari developers”, was “simply a bidirectional serial communication channel” running “at various speeds from 300.5 baud to 62.5 Kbaud (around 7K a second)”. When a cheaper model arrived in 1991, C&VG warned that “for that price you don’t get a game, link-up cable or power adaptor”. See the Atari Lynx entry for the machine.
Sega’s Game Gear had a link socket too. C&VG’s report on the Japanese launch in December 1990 listed “a link-up lead” among the add-ons Sega planned, and in America the Gear-to-Gear Cable was sold separately “for head-to-head competition”. Some games used it for co-operation instead: in the Game Gear Streets of Rage, “with a Gear-to-Gear cable, you and a friend can both play, and team up against the common foe”. Linked games needed a cartridge in each machine: “With a second cartridge and a Gear-to-Gear cable, you and a friend can take on the enemy together,” as Sega Visions put it for another game in the same issue. Documentation compiled by the SMS Power! community describes the port as an ordinary serial line with handshaking, which interrupts the processor when a byte arrives, rather than the Game Boy’s shared clock.
Pokémon
As Tajiri saw it, Game Boy owners were using the cable to fight; he wanted them to trade. Nintendo Power’s preview of May 1998 explained what that meant for American players: “the two editions will feature the exact same game, but not the same mix of monsters. While a particular monster may be common and easy to find in the Red edition of the game, it may be rare and much tougher to find in the Blue edition. Therefore, if you can’t locate a specific Pokémon in your Game Pak, you’ll have to go to another player with a different edition of the game to find it.” Battles ran over the same cable: “the victor will take home experience points”, but nothing could be captured that way.
By February 1999 the magazine was running a “Pokémon Link Cable Special”. Trading happened in a “Cable Club” inside any Pokémon Center once two machines were connected, and the design had one more reason to need a friend: “Some Pokémon evolve only after they are traded. If you have one of this type, you’ll have to trade it away to make it evolve, then trade again to get it back.”
Camera and Printer
The link was not only for games. The 1998 Game Boy Camera could “Game Link to another other Camera” to swap pictures, and printed to the Game Boy Printer, a separate peripheral on the same port; Nintendo Power called the combination a “Funtography studio” with tools “to doctor, develop, print and trade your photographs”.
After the cable
Players took to it. By November 1991 Nintendo Power was printing “Letters From Game Link Dreamers”, readers’ ideas for link-up games that ranged “from body-slamming the Hulkster to joining forces with Link to terminating Arnold”. Pokémon kept the idea going on newer hardware. When Fire Red and Leaf Green remade the first games for the Game Boy Advance in 2004, Nintendo’s Japanese advertising pushed “the new GBA wireless adapter and multiplayer features”, and when Red, Blue and Yellow were rereleased for the Nintendo 3DS in 2016, local wireless did the cable’s job.
Sources
- Nintendo Power, issue 8 (September/October 1989): Game Boy launch feature (the Video Link Cable in the box, two screens, the Video Link Symbol) and Tetris strategy (line transfers).
- Computer and Video Games, issue 101 (April 1990), pp. 76-77: hand-held history feature.
- Mean Machines, issue 12 (September 1991): Special Reserve advertisement listing the Game Boy pack.
- Nintendo Power, issue 20 (January 1991), p. 74: F-1 Race and the four-player adapter. Issue 25 (June 1991), pp. 61 and 70: the Four-Player Adapter, F-1 Race, Super R.C. Pro-Am by Rare, the GL and GL-4 ratings and the Player’s Poll. Issue 30 (November 1991): “Letters From Game Link Dreamers”.
- Nintendo, Game Boy Programming Manual, version 1.1 (1999), sections 1.1-1.5 and 2.5.1: the serial connector, the SB and SC registers, the transfer, the 8 kHz clock and the conversion connector.
- The Games Machine, issue 26 (January 1990): interview with R.J. Mical and Dave Needle. RAZE, issue 10 (August 1991), pp. 20-21: ComLynx. Computer and Video Games, issue 112 (March 1991): the $99 Lynx.
- Computer and Video Games, issue 109 (December 1990): Game Gear launch news. Sega Visions, vol. 1 no. 6 (August 1991), p. 48: Gear-to-Gear Cable advertisement and Joe Montana Football. Sega Visions, vol. 1 no. 9 (August 1992), p. 16: Streets of Rage.
- SMS Power!, “Gear to Gear Cable” development page (web, secondary): the port’s serial mode. https://www.smspower.org/Development/GearToGearCable
- “The Ultimate Game Freak”, TIME Asia, 22 November 1999 (web, secondary): Tajiri on the cable. https://time.com/archive/6951818/the-ultimate-game-freak/
- Nintendo Power, issue 108 (May 1998): Pokémon preview. Issue 109 (June 1998): Game Boy Camera feature and review. Issue 117 (February 1999), p. 100: Pokémon Link Cable Special.
- Edge, issue 134 (March 2004), p. 21: Japanese advertising for Fire Red and Leaf Green. The 3DS release of 27 February 2016: as cited in the Pokémon Red and Blue entry.