> IIRC, Codemasters and others discovered the magic numbers necessary to include in the header of the NES cart in order for it to boot

> I'm hazy on the NES-specifics.

I'll fill you in.

The ROM on NES carts doesn't have a header (the ROM files floating around on the Internet do but those aren't part of the cartridge data) - the NES has no firmware or OS. What it is is that the NES console, along with each cart, has a chip called a CIC that was only available from Nintendo, and only if you were a paid licensee. The CIC in the console resets the console constantly unless it handshakes with the CIC on the cartridge.

There were ways to disable the chip; some things I've read say having something on the cart send a voltage spike would disable it. I think Tengen reverse engineered it and developed a compatible chip, they got sued.

As far as the Sega Genesis, I do know a later revision of the Genesis motherboard had a boot ROM and also required the cart to write ASCII 'SEGA' to some I/O ports, otherwise the video chip would not work. The idea was that copying this without authorization was a trademark infringement, but I think a later lawsuit made that tactic legally worthless.

Arcade boards of the 80's and early 90's have some interesting schemes. A number of Capcom games have decryption keys in a RAM that's powered by a 'suicide battery' and if the battery ever dies or is tampered with, the keys are gone and the board stops working.