WS Flash Masta USB (Cartridge for WonderSwan)


Use the WS Flash Masta USB to upload files from your computer to the cartridge via built-in micro USB and play them on your WonderSwan, WonderSwan Color, or SwanCrystal console.

Please read the full description for important information.

Out of stock


The WS Flash Masta USB cartridge will accept 16 ROM files (one of which will likely be a menu) via USB and allow you to play them on your WonderSwan, WonderSwan Color, or SwanCrystal game console.

To upload ROMs to the cartridge, use the software found at Most users will want to flash a ROM-selector menu to the first slot. This will allow you to select the other slots upon bootup.

Look closely at the product photo. That is what you will receive. This cartridge currently has no plastic shell or casing. It is a circuit board that is designed to fit into your WonderSwan game console without any plastic shell.

This cartridge is functionally equivalent to the red early adopter version board we made in May. To read more information about that (which directly applies to this green cartridge), please see this forum thread:

As far as functionality goes, there are some items to be aware of. Not all ROMs work 100%. If you want to know more about what ROMs have problems, please see page 8 of the aforementioned thread (in particular, please see post #76 and post #80). Notice that some ROMs require a patch to work properly while a small percentage just fail to run. If any of the ROMs mentioned are of particular interest to you, I suggest that you post in that thread to see if anyone can provide more information.

Also, you may notice that the cartridge features a MicroSD card slot. This is intended for future expansion. The menu system currently does not make use of the MicroSD slot. We hope that future updates will make full use of the SD option, but we can not guarantee that will happen. The hardware has been tested, but there has been little development on the software side thus far.

Another item to make note of is that while the ROM area of the cartridge has 16 slots, the SRAM (gamesave) area does not have separate slots. This means that you can select different slots, but they will share the SRAM area. A game selection may overwrite other slot’s savegame data. Currently, playing a game may interfere with another slot’s savegame information. This may or may not be changed in the future.

Additional information

Weight 0.1875 lbs