This cartridge allows replacing the KERNAL (i.e.: operating system) of a Commodore C64 computer with one that is stored on an external cartridge. Actually it can store up to 8 KERNAL images, which can then be selected by jumpers. This makes it very easy to switch among KERNALs at will, without the need of opening the C64 every time. For more information please visit https://github.com/SukkoPera/OpenC64KernalCart.