The CuttleCart aka CC3 by Schell Electronics fits into the Intellivision cartridge slot, with a MicroSD card port to hold game ROMS. From 2007 until the LTO Flash was released, it was the primary commercial means to have a single "cartridge" in a console and play different games by selecting from a menu.
In 2023, the Windows and Linux executables for interfacing with the hardware fail to connect without emitting error messages.
Media Links:
media0101.intvprime.com/ba4ef/intellivision-echo/Hardware-Components/Cartridge-Alternatives/Cuttle-Cart-01.jpg
media0101.intvprime.com/ba4ef/intellivision-echo/Hardware-Components/Cartridge-Alternatives/Cuttle-Cart-02a.jpg
media0101.intvprime.com/ba4ef/intellivision-echo/Hardware-Components/Cartridge-Alternatives/Cuttle-Cart-02b.jpg
media0101.intvprime.com/ba4ef/intellivision-echo/Hardware-Components/Cartridge-Alternatives/Cuttle-Cart-03.jpg
Source Links:
web.archive.org/web/20210510044914/www.intellivisionrevolution.com/cc3-cuttle-cart-3-development-history