that is an early Piggy Back tuning chip for the ford EECV or whatever ford called the early EFI ECU's
the principle is that ford left a port or bit on the edge of the ecu PCB behind a bit of plastic that could just take a new program/map should it ever be needed the only issue is when the power is cut the tune reverts back to the one in the main chip hence why you had to leave them in.
i think the turobotechnics fords where done this way?
superchips and other co's used this unused ford option exploited it and made their on piggy back units to take aftermarket tune up chips
there is a similar thing with extra chip holes in 80-90s jap cars