xodaraP
Legendary
looks like bankswitching. pull down (or up?) resistor and you can see a switch cutout in the cartridge case.
if there's a larger, pin compatible flash memory it seems like it'd be pretty straightforward.
Or if you have a cart that has both PSOP44 and TSOP48 pads, you could have 2 BIOS chips on one cart and a switch on the enable pins (looking at the above and the wire tracing to the other side of the cart I think that may be the case here)