IIRC, Codemasters and others discovered the magic numbers necessary to include in the header of the NES cart in order for it to boot, and went on to release unlicensed games; like Micro Machines. I'm hazy on the NES-specifics.
EA reverse engineered the Genesis development kit and released their games in their own carts in large part because they refused Sega's licensing terms; in retrospect, it's similar to Epic/Apple today. Sega eventually caved.
An old Game Informer article about EA and the Genesis:
> 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.
Oh it's a much better story than that! They failed at trying to reverse engineer it so they just straight up stole the source code instead
https://en.m.wikipedia.org/wiki/CIC_(Nintendo)
>Tengen (Atari’s NES games subsidiary) took a different tactic: the corporation obtained a description of the code in the lockout chip from the United States Copyright Office by claiming that it was required to defend against present infringement claims in a legal case.[4] Tengen then used these documents to design their Rabbit chip, which duplicated the function of the 10NES.[4]
Video Game history is just amazing at times.
And, of course, not having a licenser did little to harm PC Gaming.
https://en.wikipedia.org/wiki/Video_game_crash_of_1983#Loss_...
Game consoles shouldn't be special. If the NES and Genesis hadn't had their locks broken then we wouldn't have been graced with some of the greatest entries in their catalogue. Consumers won because anti-consumer digital locks were broken.