Copying your Game Boy and Game Boy Advance cartridges, step by step

A Game Boy cartridge holds two very different things. On one side, the game, burned into read-only memory that never gets erased. On the other, your save, kept in memory powered by a coin battery soldered next to it. The game will last for decades yet. The battery will not: it was fitted twenty-five years ago and it eventually gives out, without warning. The day it does, your save is gone for good.

Copying your own cartridges is first and foremost about that: protecting what cannot be replaced. Here is the complete method for the Game Boy, Game Boy Color and Game Boy Advance.

The legal framework, in three sentences

Under French law, a backup copy of software you own is provided for by Article L122-6-1 of the French Intellectual Property Code. Video games, however, have been classed as "complex works" since a ruling by France's Court of Cassation on 25 June 2009, and no French case law settles the question of copying a cartridge you own. One point, on the other hand, is beyond doubt: downloading a ROM is copyright infringement, even if you have the original cartridge in a drawer. We are retailers, not lawyers: this is information, not legal advice.

Official sources are listed on our Where to play legally page, and the overview is in our complete guide to copying cartridges.

The hardware

You need a reader connected to a computer over USB. Three models cover all three systems with the same connector; they differ mainly in how you use them.

Add three consumables: a USB-C data cable (many cables supplied with chargers only carry power), 99% isopropyl alcohol and cotton swabs. Small tools are in our workshop section.

Preparing the cartridge

Nine read failures out of ten come from the contacts. A cartridge left in a box for twenty years carries a film of oxidation invisible to the naked eye: it sometimes boots on the original console yet fails when read, because the reader needs a stable contact for several minutes in a row.

Moisten a cotton swab with 99% isopropyl alcohol, without soaking it. Rub the contacts lengthwise, on both sides, until the cotton comes out clean. Switch to a new one as soon as it turns grey, otherwise you are putting the grime back. Let it dry for ten minutes before inserting anything.

Installing the software

With the GBxCart RW

The go-to software is FlashGBX, developed by Lesserkuma, free under the GPLv3 licence, at version 5.0.1 since June 2026. It runs on 64-bit Windows 10 and 11, on Linux as an AppImage and on macOS Sequoia 15 or later. On Windows, take the installer package rather than the compressed archive: it includes the CH340/CH341 drivers the device needs. Plug the reader back in afterwards, otherwise it will not be detected.

With the Joey Jr

Nothing to install: once plugged in, it shows up as a removable drive. BennVenn also provides JoeyGUI, and FlashGBX supports it — on macOS, first run the Joey Jr firmware update utility.

With the GB Operator

Epilogue provides its own software, Playback, for Windows 10 or later, macOS 12 or later and Linux via Flatpak. It also runs on Steam Deck and ROG Ally. An LED on the device shows whether the inserted cartridge is official or not.

Reading the ROM, screen by screen

First connect the reader to the computer, insert the cartridge all the way in, then launch the software. In FlashGBX, choose the matching mode, Game Boy or Game Boy Advance: this is the most common first-timer mistake. The information panel then shows the title read from the header, the detected ROM size, the save type and the header checksum. Check that the title matches the game in your hand; if not, take the cartridge out and clean it again.

Then start the read (Backup ROM) and choose the destination. The resulting file will have the extension .gb, .gbc or .gba depending on the system.

Once the read is finished, do a second one and compare the two files. If they are identical, the copy is good; if they differ, the contact was unstable: clean again and start over. FlashGBX also produces a read report, handy for an entire collection.

Backing up save data, separately

This is the most important step in the article, and it is the one people skip. The ROM file you have just obtained is identical to the one any other owner of the same game will get. Your save, on the other hand, exists in only one copy in the world: a hundred and forty hours of Pokémon Silver, thirty kilobytes, and a battery from 1999 as its only protection.

It is copied through a separate function (Backup Save Data), which usually produces a .sav file, instantly. On Game Boy and Game Boy Color, it weighs 8 to 32 KB. On Game Boy Advance, the size depends on the technology: 512 bytes or 8 KB for EEPROM, 32 KB for SRAM, 64 or 128 KB for flash memory.

One detail explains a lot of problems: the save type is not written in the header of a Game Boy Advance cartridge. Software guesses it by searching the ROM for a signature left by Nintendo's official libraries: EEPROM_V, SRAM_V, FLASH_V, FLASH512_V or FLASH1M_V. Some games contain several, contradictory ones. If the file size surprises you, force the type in the software and start again.

Name the files with the game and the date, and keep two copies on two different media; our article on managing saves details the organisation to adopt.

Putting a save back on the cartridge

The reverse operation (Restore Save Data) writes a file back into the cartridge's memory: after a battery replacement, or to bring back a game you progressed on a handheld console. Three precautions. Copy the current save before writing over it, even if you think it is empty: writing is irreversible. Check that the file to restore is exactly the same size as the one produced when reading. Do not unplug anything while writing. Finally, check the result by loading the save on a real console, not by re-reading the file.

Special cases

Cartridges with an internal clock

Some cartridges include, in addition to the save, a real-time clock that runs permanently off the battery: Pokémon Gold, Silver and Crystal on Game Boy Color; Pokémon Ruby, Sapphire and Emerald and the three Boktai games on Game Boy Advance.

FlashGBX backs up and restores this clock's registers along with the save data, which preserves day/night cycles and daily events. If the battery is already dead, the clock restarts at 01/01/2000, and in Ruby, Sapphire and Emerald the game does not let you set it again. insideGadgets offers a utility to write a new date to it, but the operation requires resetting an offset stored in the save — do it on a copy.

Counterfeit cartridges

The reader almost always exposes them: a ROM size that matches no official size, a header checksum that does not add up, a save type that cannot be found, two successive reads that do not give the same file, or a chip that responds to CFI query commands — an original ROM does not respond to them, a reproduction flash chip does.

The GB Operator shows the verdict with an LED; with FlashGBX, run the analysis function (Analyze Flash Cart) before any read if in doubt. A reproduction usually copies without any problem, but the resulting file is not the original ROM: often a modified version, sometimes a different game from the one on the label.

Game Boy Camera cartridges

Here, what is valuable is not the game but its content. The cartridge includes 128 KB of battery-backed memory and stores up to thirty 128 × 112 pixel photos in four shades of grey. These photos live in the save, not in the ROM: copy the save data as usual, then extract the images. FlashGBX can decode and export the photos from a Game Boy Camera save, and insideGadgets offers a dedicated program that outputs them as BMP.

What to do with the file next

Your .gb, .gbc and .gba files go in the folder intended for each system on the microSD card, and the saves in a separate folder whose location varies by firmware. We will not go over the folder structure again here: it is detailed in our article on organising files. These files come from your cartridges and stay with you: putting them online falls outside the framework described above.

Three common problems

1. The reader does not show up anywhere. Nine times out of ten, it is the cable: many cables supplied with chargers do not carry data. Try another one, plug directly into the computer rather than into an unpowered hub, and on Windows check the CH340/CH341 driver if you use a GBxCart.
2. The information displayed makes no sense — unreadable title, absurd size, wrong checksum. This is a contact fault: clean both sides again, dry, and reinsert fully. If the problem affects only one cartridge while the others work, it comes from that cartridge and not the reader.
3. The game rejects the restored save. Check the file size, which must match exactly the one produced when reading, then the detected save type, which can be wrong on Game Boy Advance. Finally, the file's origin: a save from an emulator may contain a header the cartridge does not expect. Our guide to the fourteen reasons a game will not launch covers related cases on the console side.

FAQ

Where to start

One thing to remember: copy your saves first, the ROMs can wait. One evening is enough to protect an entire collection. The hardware is in our cartridge readers collection.