sammargh
Professional
The security chip is a sort of number tumbler based on the bits coming in and going out, I think it is too complex to just use a PLD. I had considered just skipping making a chip and emulating the serial communication as it's pretty simplistic bit math but haven't had time to give it a try. However if you're aware of a method that already exists to make the chip I'm all ears.Yes I did mention this in the original post. I also mentioned both are dumped in Mame and it's possible to make a repro protection chip, so it's not really a problem.Look on the ZN-1 motherboard and you should see a protection chip labeled TW01. This is unique to the game itself and locked to Atari corp bios. On the game portion there should be one labeled TW02.
Edit: looking closer at the board yours is missing the protection chip on the game portion at least. It should go in that socket in the bottom-right next to the unpopulated header.