Game Boy Link

From HwB

Todo: This page needs some editing.

Known as EXT on Nintendo Game Boy Advance (GBA) and EXT.1 on Nintendo Game Boy Advance SP (GBA SP).




|  2  4  6  | 
 \_1_ 3 _5_/  (at handheld game)


/ 6  4  2 \ 
\_5_ 3 _1_/  (at cable)

Old "8bit" Plug:

|  6  4  2  |
 \_5__3__1_/   (at cable)
Pin Name Cable
1 VDD35 N/A
2 SO Red
3 SI Orange
4 SD Brown
5 SC Green
6 GND Blue
Shield Shield

SI=Data In, SO=Data Out, SD/SC Flow control

Note: The pin numbers and names are printed on the GBA mainboard, colors as used in Nintendos AGB-005 and older 8bit cables.



GBA Cable

Big Plug  Middle Socket  Small Plug    
 SI _________________     ____ SI      
 SO ____________SO   |__ | ___ SO      
 SD ____________SD____________ SD      
 SC ____________SC____________ SC      

8bit Gameboy Cable

Plug 1         Plug 2
 SI ______  ______SI
 SO ______><______SO
 SD               SD
 SC _____________ SC


Normal Connection

Just connect the plugs to the two GBAs and leave the Middle Socket disconnected, in this mode both GBAs may behave as master or slave, regardless of whether using big or small plugs. The GBA is (NOT ???) able to communicate in Normal mode with MultiPlay cables which do not have crossed SI/SO lines.

Multi-Play Connection

Connect two GBAs as normal, for each further GBAs connect an additional cable to the Middle socket of the first (or further) cable(s), up to four GBAs may be connected by using up to three cables. The GBA which is connected to a Small Plug is master, the slaves are all connected to Large Plugs. (Only small plugs fit into the Middle Socket, so it's not possible to mess up something here).

Multi-Boot Connection

MultiBoot (SingleGamepak) is typically using Multi-Play communication, in this case it is important that the Small plug is connected to the master/sender (ie. to the GBA that contains the cartridge).

Non-GBA Mode Connection

First of all, it is not possible to link between 32bit GBA games and 8bit games, parts because of different cable protocol, and parts because of different signal voltages. However, when a 8bit cartridge is inserted (the GBA is switched into 8bit compatibility mode) it may be connected to other 8bit games (monochrome gameboys, CGBs, or to other GBAs which are in 8bit mode also, but not to GBAs in 32bit mode). When using 8bit link mode, an 8bit link cable must be used. The GBA link cables won't work, see below modification though.

Using a GBA 32bit cable for 8bit communication

Open the middle socket, and disconnect Small Plugs SI from GND, and connect SI to Large Plugs SO instead. You may also want to install a switch that allows to switch between SO and GND, the GND signal should be required for MultiPlay communication only though. Also, cut off the plastic ledge from the plugs so that they fit into 8bit gameboy sockets.

Using a GBA 8bit cable for 32bit communication

The cable should theoretically work as is, as the grounded SI would be required for MultiPlay communication only. However, software that uses SD for Slave-Ready detection won't work unless when adding a SD-to-SD connection (the 8bit plugs probably do not even contain SD pins though).