Instructions:
1. Load Bizhawk
2. Go under tools and select Multi-disk Bundler
3. Select Browse. Enter a name for the XML file you want to create. This will be opened later on to get the game to run Dual Gameboy mode.
4. Set the System Drop down to GB.
5. Set the ROMs you want to be loaded. Archived ROMs are not loaded (Zip, Rar, 7Z, ect.) by BizHawk in Multi-disk mode and will give an error message.
6. Select Save and Run
7. It should run.
Possible Questions/Issues
Q: The Audio is weird/is bad/is mixed.
A: BizHawk will run BOTH instances of the Gameboy with audio enabled. If you want to hear audio from only one Gameboy instance, go under GB Link and select Settings. Then two tabs will be shown. Left Gameboy and Right Gameboy. The Checkbox for Mute Audio, applies to that Gameboy instance.
Q: Save and Run is not enabled.
A: The XML file must be saved to a valid location, The System must be Selected, and two ROMs must be set.
Q: I get a black screen/Firmware warning/invalid ROM.
A: You probably didn't set the System to GB. PSX and Apple II are also options. Double check this.
Q: I get an error message, "DGB Load Error System.InvalidOperationException"
A: You attempted to load an archive instead of an extracted ROM. Extract the ROM(s) and try again.
Q: How do I change a setting on an instance of the Gameboy?
A: Go under GB Link and select Settings. Configure away.
Q: What features/issues does the Dual Gameboy have?
A: The same features and issues as the current Gameboy core (Gambatte).
Q: How do I trade Pokemon?
A: It's usually in the Pokemon Center. Look for something there.
Q: Is there a way to do dual GBA?
A: As of 1.11.3, no.
Q: What are the controls?
A: Go to Config, then Controllers. Player 1 is the left Gameboy. Player 2 is the Right Gameboy.
Q: What's Toggle Cable for?
A: Some games may want you to disconnect the link cable for some reason. Or, if you want to duplicate Pokemon in Blue/Green/Red, it is a required function.
Q: How do I make the game not look Monocrome?
A: Under GB Link, select settings. Then select Pallete. Choose from the preloaded options or one you downloaded.
Q: How can I get my Save RAM (SRAM) into the Dual GB?
A: Hex Editor. If you don't know what that means or what to do, try this.
NOTE! NO Support will be offered by the developers or myself for users who don't know what do to or are confused by these instructions.
How to Transfer SRAM from Single Instance to Dual Instance:
1. Have SRAM for the Single Instance game you want to transfer data from, and SRAM created for Dual Instance games. You can verify this by looking in the folder Gameboy\SaveRAM
2. Get a Hex Editor.
3. Open SRAM for the Single Instance of your game in the Hex Editor.
4. Copy ALL data from the Single Instance SRAM file. Note if Hex or Normal or Binary or whatever the copy method you selected.
5. Note the ending Offset from the Single Instance SRAM file.
Pokemon Blue/Crystal/Gold/Green/Red/Silver is 32767.
Other Gameboy games may have different SRAM sizes.
Do NOT assume on your Offset value. Double check it.
6. Open the Dual Instance SRAM file in the hex editor.
7A. If the game you want to transfer data to is on the left, then you paste the data over the old SRAM. DO NOT Insert the Data. You want to overwrite the data. Start at Offset Zero and Paste the data over the existing data.
7B. If the Game you want to transfer data to is on the right, then determine the length of the left game's SRAM. You can do this by running the game in single instance mode and saving. Repeat the above steps for finding the offset value. Then add one to the offset value from the left game's offset, to get the right game's offset value. Having two Pokemon games in Dual Instance mode, would get the result 32768 for the right Gameboy's instance SRAM Offset value. Repeat the above instructions for copying data and overwriting the data. Be sure you changed the offset value or you will overwrite the left Gameboy's SRAM instead. Or worse, ruin the dual Gameboy's SRAM.
8. Enjoy your SRAM in it's new Dual Gameboy home. Your Single Instance SRAM is NOT lost or effected by this so long as you copy from the file and don't change the file.
Or you can use this:
Multi Game SaveRAM writer:
https://1drv.ms/u/s!AnSqHbELt2wAie030SldXIBe3_cWyg