YOU MUST ORDER WITH ENIG FINISH AT 0.8MM THICKNESS!

This is a slightly updated design of my original flashable MBC3-based multicart for the Game Boy. You can make a 2-in-1 or 4-in-1 cartridge, that changes games based on a button press or power cycling the Game Boy. With this board you can also make a single game, but with the addition of a pressable reset button on the cartridge.

This MBC3 cartridge uses new old stock 29F033 EEPROM chips and battery-backed SRAM.

The features are as follows:

• Able to make a cartridge with either 2x 2 MB games or 4x 1 MB games
• Adds a pressable button to the cartridge (no shell cutting required)
• The button can be configured to cycle games on the cart, reset the console, or both
• Configurable to have separate save data for each game, or to share the same save data across multiple games
• Fully compatible with the GBxCart RW so you can transfer games and save files to and from the board

Some examples of fun cartridges you can make with this board are:

• A single Pokemon game that has a reset button
• Both Pokemon Gold and Silver with separate saves
• Both Pokemon Gold and Silver with *the same* save (save files are compatible between versions!)
• Both Pokemon Gold and Silver with *the same* save that can switch between versions *during gameplay without resetting* (hotswap!)
• A single copy of Mary-Kate and Ashley - Pocket Planner with two separate save files

Along with reading the GitHub repo IN FULL, please review the following before purchasing:

• To use this board, you need to have an original Game Boy game that uses an MBC3 mapper chip.
• You will need to remove the MBC5 from your donor cartridge for use on this board. This will require a hot air rework station or a hot plate. There's a list below of other parts you can re-use from the donor cartridge.
• When soldering parts on, it's a good idea to put kapton tape or otherwise cover the bottom cartridge edge. You do not want to get solder on the cartridge contacts.
• I am not responsible for any damage you do to your self or your property. Attempt this project at your own risk.
• I do not guarantee design compatibility. You may encounter issues with certain games. There is also a chance I have made an error in the design or the BOM - if this is the case, I will do everything I can to address the problem as quickly as possible.
• If you are using this board to make games other than for personal use, you must have permission from the originator to use and distribute any ROM images or other related material. You are responsible for making sure you adhere to any license requirements.
• DO NOT use my circuit boards for profiting from stolen work - this especially includes homebrew content, ROM hacks, and using fan-made labels without permission from the originator. Support original creators!

All gerbers and source files can be found in the GitHub repo, as this project is fully open source with attribution. Please view the repository for BOM information.

https://github.com/MouseBiteLabs/Game-Boy-Cartridges/tree/main/MBC3%20Multicart