Various Flash Cartridgers for various consoles, they don't need a microsd because they have an intenal memory enough to save the full romset. They cdan be programmed simply connecting the cartridge to a PC using a common USB to type-c cable, it will works like a flash drive.
PICOLECO cart for the COLECOVISION - € 35
PIRTO II cart for the INTELLIVISION - € 35
PICOPAC cart for the Philips VIDEOPAC and clones - € 35
PICOA10400 cart for the ATARI 7800 and 2600 - € 40
SD-1000 cart for the SEGA SC3000 / SG1000 - € 35
ATARI XE/XL cart for the ATARI XE130 / XL800 - € 35
They are plug and play, with the romset already inside
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