PRIVATE Beta WS Flash Masta USB (Cartridge for WonderSwan)


Do not purchase this product without first talking to Ed.

This is a beta test release batch of the newly redesigned WS Flash Masta USB. This cartridge is intended and expected to work the same as the previous WS Flash Masta Cartridge. It is not expected to have new functionality. The redesign was to make this cartridge easier to source parts for and easier to manufacture, so that we can hopefully keep these in stock instead of making very small batches and usually being sold out.

These are not yet ready to ship, but we expect to have them ready in the next 2 weeks.

NOTE: This “beta test” release is for US customers only. In case we find an unexpected problem, we will recall these cartridges for repair/replacement/refund. Because of that, we will not be shipping them internationally. If we receive an international order for this item, we will cancel and refund the order.

If you are in the US and want to purchase this, please be prepared to offer feedback, especially if you encounter any problems.

Please see for additional information before purchasing.

2 in stock

SKU: WS-FM_5.1_PRIVATE_BETA Category: Tags: , , , , ,


If this test batch goes as expected, then we will be making a larger batch and opening the sales to worldwide customers.

Note that this cartridge does not offer fully 100 compatibility, but we believe that it is working just as good as the previous release of the WS Flash Masta. The main issue with compatibility is with ROMs that use EEPROM for savegame data, and many of those can be patched to work with SRAM. Please see this thread that gets into details about specifics about compatibility.

There has also been a new thread started for this new “v5.1” cartridge (that you’re currently looking at) at

Additional information

Weight 0.1875 lbs