Custom firmware version 2.03.00 is available for download.
This custom firmware has support for a new SEGA Master System and SEGA Game Gear emulator build by d_smagin. The emulator isn't the final version but it already runs very good in both native RES and Streched FS mode. An Aspect FS mode is going to be added later.
Enjoy and don't forget to download the updated emulator pack.