Arcade-Gauntlet_MiSTer/doc/vindctr.part.ii

This is the conversion kit that was released to convert the Atari Gauntlet arcade into a Vindicators part II arcade.

The pictures of the so called "cookie board" have been reverse engineered into a hand drawn schematic. It appears the GPC (Graphic Priority Chip) is removed from the PCB and inserted onto the cookie board socket, then the cookie board is inserted into the PCB socket where the GPC was.

The overall net effect is that two input signals to the GPC (M7 and P7) are intercepted and reconstructed by the AND and NAND gates.

Source: https://forums.arcade-museum.com/threads/vindicators-part-ii-daughterboard.411580