Game Boy Link Ports & Cables & Peripherals

When Nintendo released its first handheld console, the Game Boy, it provided a Link Port to allow two players to play games with or against each other.  That Link Port is a simple bidirectional synchronous serial port and was not very fast but it was sufficient to allow two consoles to communicate with each other over a Link Cable.  In subsequent Game Boy models the Link Port became faster but it also took on different shapes.  The Link Port was carried over to the Game Boy Advance, but there were some differences.  In this article I will go over the various cable connectors, the official products which used the Link Port or converted one kind of link port to another and how Link Cables are wired.

Connector and Compatibility Basics - The Four Generations

Game Boy Link Ports and Cable Connectors come in three sizes and four shapes.  The largest was original to the original DMG Game Boy, released in 1989.  A notable peripheral which uses the DMG link port is the Game Boy Four Player Adapter.  

The medium-sized connector was introduced with the Game Boy Pocket (MGB) in 1996.  This connector is identical electrically to the DMG connector, but it is a physically smaller connector.  The MGB connector was used on the Game Boy Light, Super Game Boy 2, Game Boy Color in its 8-bit form.  A notable peripheral which uses the Medium link port is the Game Boy Printer.  The Game Boy Color supports faster data transfer modes compared to the Game Boy and Game Boy Pocket and its derivatives but does not require different cables to handle the higher speeds.  With the correct cable or adapter, any MGB cable or peripheral can work with an original DMG Game Boy.

The Game Boy Advance, Game Boy Advance SP and the Game Boy Player use a slightly modified MGB connector and are backwards compatible with the 8-bit Link Cables and Peripherals.  The GBA has more advanced functionality which necessitate wiring changes in its own Link Cables and has GBA-exclusive peripherals like the Wireless Adapter.  GBA Link Cables and Peripherals have a bump on their connectors to prevent insertion into an MGB connector.  In short, use 8-bit cables when using 8-bit games and peripherals and use GBA cables when using GBA games and peripherals, except as noted below.

The smallest connector used as a Link Port was introduced with the Game Boy Micro, released in 2005.  The Micro has a single port which performs double duty as both a Link Port and a Charging Port.  As the final iteration of the Game Boy Advance hardware, only basic support was offered for the Micro Port.  Even with adapters, its Link Port is not compatible with MGB 8-bit cables and peripherals as the Micro is not compatible with 8-bit software.

In the lists below, an output connector is male in construction and an input connector is female in construction.

Licensed Devices Supporting the DMG Connector

DMG-01: Game Boy

DMG-04: Game Link Cable

Two DMG outputs, one on each end of the cable.  Unlike later cables, this cable was included with the original off-white DMG units, but not usually the "Play-it-Loud" units.

DMG-07: Four Player Adapter

This adapter has one output DMG cable and three inputs for DMG-04 cables.  No Game Boy Color games supported this adapter.

DMG-14 : Universal Game Link Adapter

This small adapter has a MGB input and a DMG output.  May be bundled with MGB-008.

Barcode Boy

The Barcode Boy was developed and released by Namco(t) exclusively in Japan.  This device was released in a package with a game called Battle Space (Set 1) and later with Monster Maker: Barcode Saga (Set 2).  Each game came with its own cards to scan, and the Barcode Boy contained a scanner which sat on top of the Game Boy.  Barcode card scanning games were a peculiar Japanese phenomenon which never caught on outside that country.  A small Link Port cable connected the scanner to the Game Boy.  For reasons unknown, this may not work in anything other than a system with a DMG connector.

WorkBoy Prototype

The WorkBoy was a cartridge that contained several productivity applications and was announced for release and shown at at least one trade show but ultimately was never released.  A small keyboard plugged into the Link Port and was required to access most of the WorkBoy's functions.  The keyboard is powered by two coin-cell batteries and has a built-in speaker for an alarm.  The WorkBoy and its keyboard were developed by Fabtek in conjunction with Nintendo.  Only two prototypes of the keyboard were made, but the WorkBoy prototype cartridge has been dumped.

Licensed Devices Supporting the MGB Connector

MGB-001: Game Boy Pocket

MGB-004: Game Link Cable Adapter

This "boxy" adapter has a DMG input and an MGB output.

MGB-007: Game Boy Printer

Both Game Boy and Game Boy Color games support the Printer, as does the Game Boy Camera.  Requires a Link Cable.

MGB-008: Game Link Cable

Two MGB outputs, one on each end of the cable.

MGB-010: Universal Game Link Cable

One MGB output on one end of the cable, split into one MGB output and one DMG output on the other end of the cable.  Only one device may be plugged into the split end of the cable.

MGB-101: Game Boy Light

SHVC-042: Super Game Boy 2

CGB-001: Game Boy Color

CGB-003: Game Link Cable

Identical to MGB-008

GBC-005: Mobile Adapter GB

Japan-only, three colors exist, blue, yellow & red, for different networks and these adapters connect to cell phones.  Supported by several Japanese GBC and GBA games.

Barcode Taisen Bardigun

Works on the same lines as the Barcode Boy, used by the Japanese game Barcode Taisen Bardigun and its included barcode cards.  Unlike the Barcode Boy, this device has a cable so it does not need to be attached to a console.

Turbo File GB

The ASCII Turbo File GB works on the same principle as the Famicom and Super Famicom Turbo File devices, it is external non-volatile memory which can be used by supporting games to save the progress of a game.  The device supports 128KiB of Flash Memory, allowing for 15 save slots, and requires batteries to power on.  Two Japanese games support this device, RPG Tsukuru GB & Uchuu Nin Tanaka Tarou De RPG Tsukuru GB2, and both are GBC-only games.  The Turbo File GB has a slot which can accept Yellow 128KiB Memory cards to add more storage.  A physical write protect switch can protect the memory from being overwritten by accident.

Singer/Jaguar Digital Sewing Machines

The Singer IZEK-1500 is a Sewing Machine which has a Link Cable (connected inside the machine) and can be controlled by a Game Boy.  Jaguar also made a pair of Sewing Machines, the JN-100 and the JN-2000, which had Link Cables built in.  The JN-100 was released in Japan and Europe and is essentially identical to the Singer IZEK-1500.  The JN-2000 was only released in Japan and has a special embroidery arm. There were seven special cartridges which could instruct the machine to print stitches, design special patterns and save stitch combinations.  Five of these cartridges are embroidery cartridges and only work with the JN-2000.

Power Antenna + Bug Sensor

Despite their impressive names, these devices are little more than a single LED on a stick which attaches to the Link Port and emit light during game events.  The Power Antenna is intended only for Keitai Denjuu Telefang - Power Version & Keitai Denjuu Telefang - Speed Version.  The Bug Sensor is intended only for Network Boukenki Bugsite - Alpha Version and Network Boukenki Bugsite - Beta Version.  Despite intentions, any of these devices will work with any of these Japanese-only games.

Licensed Devices Supporting the GBA Connector

AGB-001: Game Boy Advance

AGB-005: GBA Game Link Cable

An official GBA Link Cable has two GBA output connectors, one colored purple, one gray, on either end of the cable and an GBA input connect in a purple box in the middle of the cable.  The GBA supports up to four players using three cables.  The purple connector should plug into Player 1 if you are using a game which permits multiplayer with only one game cartridge. The purple connectors are shaped to plug into the purple boxes, the gray connectors are encased in thicker plastic and will not fit in the purple box. The ports on this cable are rounded as opposed to the trapezoid shape of the GBA console's port.

AGB-006: Infra Red Link Adapter

Adds infrared support for one GBA game, Cyberdrive Zoids: Kizuusenshi no Hyuu.  Has retaining clips.

AGB-014: e-Reader (Overseas) & e-Reader Plus (Japan)

The first iteration of the e-Reader in Japan did not have a link cable passthrough port. The second iteration of the Japanese e-Reader, the e-Reader Plus, has a link cable passthrough port and is identical in functionality to e-Readers released outside of Japan. The passthrough port is only required for the original GBA, the GBA SP's port is not blocked by the e-Reader. Like the official GBA Link Cable, the e-Reader uses the rounded connector.

AGB-015: Wireless Adapter

Released later in the GBA's life, this adapter allows for multiplayer gaming but is not a substitute for a wired link cable.  It requires direct support by a game.  Has retaining clips.

AGS-001: Game Boy Advance SP

AGS-101: Game Boy Advance SP (Backlit screen)

DOL-011: Game Boy Advance Cable

This cable has a MGB connector on one end and a GameCube controller port on the other end and is used any GameCube software which supports it.  The Game Boy Player can use a Game Boy Advance as the controller when this cable is connected.  Has retaining clips.

Soul Doll Adapter

Well before Skylanders' Portal of Power and its figurines which were able to send and receive data via an RFID chip, the Soul Adapter did something similar in the two Legendz games released for the GBA in Japan. At certain points in the game, the game would ask for Soul Dolls to conjure up a monster the player could use to fight in these RPG games, which would be placed on the Soul Adapter.  Bandai released 103 Soul Dolls, but the included Hexadragon Soul Doll could be used to complete the game.  Each Soul Doll has a 1KiB EEPROM chip inside it to save the progress for each monster and there are pads on the PCB which provide electrical contacts which touch contacts provided by the Soul Adapter.

Battle Chip Gate

The Battle Chip Gates are supported by some of the later Rockman.EXE and Mega Man Battle Network games.  Here is the list of games (if the US title is listed it includes the corresponding Japanese title) which support these devices. In the supported games, the Gates could accept a small "battle chip", which looks something like an SD card, which is inserted into the a slot in the connected Gate.  Each battle chip would give the player a new power or ability in addition to the abilities you would unlock by playing the games and earning the battle chips in-game.  Although the Battle Chip Games (of which there were three and each game only supports a specific Gate) were only released in Japan, unusually some of the US releases of the games do support the Gates and the Chips.  There were many physical chips released for the Gates and some chips only worked with one Gate.  Each Battle Chip has 11 or 12 contacts, but they do not connect to any memory chip underneath the plastic, the interconnections of the pins give a number that the Gate reads and sends to the game via the Link Port.  Has retaining clips.

Multi Plust On System

Similar in concept to the Soul Doll Adapter, the Multi Plust On System is supported by the Japanese games Bouken Yuuki Pluster World - Densetsu no Plust Gate, Bouken Yuuki Pluster World - Densetsu no Plust Gate EX & Bouken Yuuki Pluster World - Pluston GP.  The first two games are RPGs where you use the figurines, called Plusers, to summon monsters to fight battles.  The third is a racing games where the Pluster attached is the racer you use.  While the Pluster figurines are more varied in design than the monolith Soul Dolls, they cannot hold user data, they can only tell the game that a new monster is available when placed on the pedestal which attaches to the Link Port and turned.  There is no electronics inside a Pluster figurine, the spokes underneath the figure and the manner in which they fit into the base pedestal and the contacts they come into contact with on the pedestal when turned tell the program which figure is on the pedestal.  Has retaining clips.

Turbo File GBA

Nearly identical in concept, form and functionality to the Turbo File GB, made by Sammy this time.  Supported by two Japanese games, Derby Stallion Advance and RPG Tsukuru Advance.  Memory cards are blue instead of yellow.

Power Antenna 2

Identical in function, if not in form, to the Power Antenna and Bug Sensor.  Keitai Denjuu Telefang 2 - Power and Keitai Denjuu Telefang 2 - Speed are the only games which use this and are Japan exclusives.  These games can use the older Power Antenna and Bug Sensor, but the older games can only use the Power Antenna 2 on a GBA due to the bump preventing the GBA connector from being inserted into a GBC.  While it does not have a retaining clip, it does have a plastic bump that fits into one of the clip slots.

DOL-017: Game Boy Player

Licensed Devices Supporting the Micro Connector

OXY-001: Game Boy Micro

OXY-002: AC Adapter

As indicated above, the Micro port is used both for charging and powering the Micro as well as providing Link Cable support, so you cannot use both at the same time.

OXY-004: Wireless Adapter

Identical in function, if not in form, to AGB-015

OXY-008: GBA Game Link Cable

This cable is identical in function to AGB-005.  It has two Micro output connectors on either end of the cable and a box with a Micro input connector at the middle of the cable for more than two player support.  One of the connectors has a "lip" which prevents it from being plugged into the the middle connector, serving as the equivalent of the Gray connector on the AGB-005.  The connector which can plug into the box is the equivalent of the Purple connector on the AGB-005.

OXY-009: GBA Game Link Cable Adapter

An adapter with an GBA output connector on one end and a Micro input connector on the other end.  These permits one Micro to connect to up to three GBAs, but the Micro has to be Player 1 with one-cartridge multiplayer games.  There was no reverse of this adapter made.  

Missing Pins on First Party Cables and Game Link Cable Wiring

The DMG-04, MGB-008 and CGB-003 Link Cables have only 4 of 6 pins populated in their DMG output connectors.  The four pins present provide the signals necessary for communication : Serial Input, Serial Output, Serial Clock and Ground.  One pin provides +5v, so adapters with circuitry in them but otherwise unpowered like the Four Player Adapter have a fifth pin on their DMG male connector.  The Game Boy Printer takes batteries and does not need +5v from a console.  The sixth pin was not used by any device released to the public.

Link Cables are cross-wired in that Serial Input on one end of the cable goes to Serial Output on the other end of the cable and vice versa.  This makes them similar to null-modem cables.  Adapters should pass all six pins through.  Third party cables may pass all six pins through whereas the first party cables do not.  Official Link Cables starting from the MGB-008 should have RF chokes near the end of each output connector, third party cables may not.

GBA Link Cables are not cross-wired in the way 8-bit cables are and use 5 of the 6 pins, with only the +5v pin (Pin 1) being unconnected.  Adapters like the Infrared and Wireless Adapters should have the sixth pin populated because they contain circuitry which must be powered and have no other source of power.  This is how the AGB-005 connectors are wired :

Purple Connector
Pin 1 No Pin
Pin 2 Serial Out  (connected to Gray's Serial In)
Pin 3 Ground (Serial In)
Pin 4 Serial Data
Pin 5 Serial Clock
Pin 6 Ground

Middle/Box Connector
Pin 1 No Pin
Pin 2 Serial Out
Pin 3 Not Connected
Pin 4 Serial Data
Pin 5 Serial Clock
Pin 6 Ground

Gray Connector
Pin 1 No Pin
Pin 2 Serial Out
Pin 3 Serial In (connected to Purple's Serial Out)
Pin 4 Serial Data
Pin 5 Serial Clock
Pin 6 Ground

The colors of the wires inside the purple box are Green = Serial Clock, Brown = Serial Data, Red = Serial Output, Orange = Serial Input, Blue = Ground

This is the connector pinout for the GBA connector (from the console and middle connector):

 ___________  
|  2  4  6  | 
 \_1_ 3 _5_/
     '-'     

and from the purple and gray connectors:

  ___'-'___

/  1  3  5  \

|__2__4__6__|

All the connections are done at the middle box, not the end connectors.  

The GBA link port uses the shared serial data line for its communications. In this case, if you use the Purple or Master connector to connect to Player 1, the Serial Input line to that GBA will be grounded.  The Serial Output from Player 1 will be cross-wired to the Serial Input to Player 2, the Serial Output from Player 2 to the Serial Input to Player 3 and Serial Output from Player 3 to the Serial Input to Player 4.  Recall that only Purple Connectors fit in the Middle Connector.  In this example, Players 2, 3 & 4 all are using the Gray or Slave connectors to their GBAs.  For games where one cartridge can supply the game to three GBAs by sending up data to their RAMs, called "Multi-boot" mode, the console in which that cartridge is connected must be the Master.

Third party GBA Link Cables typically only support two players and do not have a middle connector. 

Did you know that if you have a pair of official GBA Link Cables, you can make them into a GB/GBC link cable by connecting the purple connector of each cable into the middle box of the other cable and use the gray connector for the consoles. This only works with the GBA systems due to the shape of the port.

Power from the Link Port and Unlicensed Link Port Accessories

In the days of the Game Boy and Game Boy Pocket, third party products rarely touched the Link Port if they needed power for things like lights or speakers, they used their own batteries or piggybacked onto the battery compartment of the Game Boy.  Devices like the Game Genie were powered through the cartridge port.  With the Game Boy Color came lighting solutions like the Nyko Worm Light, which also works on the Game Boy Pocket and the Game Boy Advance.  They usually had pass-through connectors to allow Game Link cables to continue working.  There was a device called the Boom Box Boy which was an FM radio which attached to the Link Port but only used the GBC as power source.  They did not always seek the Official Nintendo Seal of Quality.

One of the very few exceptions to the rule of passthrough and power Link Port usage by third parties is the Nyko WormCam.  This is a camera attachment peripheral for the GBA and only fits properly in the AGB-001.  It programs the GBA solely by the Link Port, it has a plastic piece which goes into the cartridge slot but does not make contact with the pins.  It was not licensed by Nintendo and there is a bar which goes across the screen as the software loads into the RAM inside the GBA in Multiboot mode.  It has a custom serial cable and software on an accompanying CD which can be used to transfer photos and such to a PC.  It also has a compartment for coin-cell batteries to power the hardware.  The Digi-Cam SP, also by Nyko, was pretty much the same idea just with a form factor that worked with the GBA SP instead of the original GBA.

Official Devices without Link Support

It is well known that the original Super Game Boy does not have a link port, but with a modification a link port can be added to that device.  The Wide Boy for Famicom and the Wide-Boy 64 CGB and AGB versions were not sold to the public but could be used by developers to test their games and by the press to get screen captures off a TV screen of a Game Boy screen.  While these devices did not have Link Ports, they could often be connected to consoles via ribbon cables and could theoretically access the Link Port.  The Visteon Dockable Entertainment System was a portable DVD player with a GBA and a cartridge slot built in but did not include a Link Port.  The device was very expensive, only sold at auto dealerships and thus is very rare today.  The Nintendo DS and DS Lite were backwards compatible with GBA cartridges but do not include a Link Port.