So I was thinking, why not? What a fun little experiment this turned out to be!

I’d been dumping EPROMs from a Sega cartridge containing Monopoly, and the board had four ROM chips fitted. While working through them, I started wondering what would happen if I removed one and tried running the game with only three installed.

Naturally, curiosity got the better of me. I pulled the EPROM from the bottom-right corner of the board, leaving the other three in place, and decided to see what the Mega Drive would make of that arrangement. There was only one way to find out!

The surprising part was that the game appeared to start normally enough. There was no immediate refusal to boot, despite having a quarter of its ROM chips missing. That was encouraging, if only because it meant something interesting might happen next.

And something interesting certainly did happen when I pressed Start! The game continued doing its thing, but what followed wasn’t exactly a normal game of Monopoly. I could still move around, although the results were wonderfully strange.

I imagine removing a different EPROM would produce a different collection of problems, depending on what data each chip contains. I only tried removing this particular one, so perhaps I’ll have to experiment with the others another day.

I’ve been describing this as a Sega prototype or test cartridge, although I haven’t established its exact development history. For now, it’s an unusual Sega cartridge with four ROMs and an excellent excuse to see what happens when one of them goes missing.

Anyway, that’s enough deliberate misbehaviour for one afternoon. I’d better get back to dumping those EPROMs before I find something else to pull apart!