A Special Cartridge with a socket that a allows easy modification of the build in ROM software.
Such thing can be made by "cannibalizing" an existing Cartridge (Let's say... a GX4000 Burnin'Rubber Cartridge, as it is the most common one). Remove properly the ROM (the biggest chip) but beware to harm nothing. Then file a hole on your Cartridge, add a ROM/EPROM socket...there you are.
Of course the most important chip remains the ACID and should be treated with exceptional care.
Another main problem may come from the necessity to open the Cartridge without broking anything.
Instead of filing a big hole, you may use somle extra connections (wires), smaller holes and then the ROM socket is fixed on the cartridge (as seen on those pictures).
The Multi EPROM cartridge shown here seems of a proffessionnal quality. The Chip socket is epicly good as it allows to remove the EPROM/ROM without harming it.
