tepples wrote:
Just a wild guess, but Nintendo's factory probably tested 2A03 CPUs received from Ricoh, and the test rig had a 2A03 socket and some additional MMIO port that controls the test mode pin, letting the program switch between test mode and run mode. But I imagine that sort of stuff would be even more obscure than the Nintendo PlayStation. So until such a test rig surfaces, I oppose baking into NES 2.0 a means to distribute a firmware for it.
I'm not entirely certain the logic of why something that is inherently in the 2a03G and exists would not be added into NES 2.0 specs; as opposed to Famiclones that are based on the hardware but may have different PPUs or palettes. Vs. and Dual units are available as well. It's apparent that the NES 2.0 format's purpose is to include as many multicarts, Famiclones, arcade hardware, peripherals, and features of the NES as possible; making it as future-proof as it can be; including additions of homebrew mappers and peripherals.
If someone really wanted to, there shouldn't be any way to stop them from creating a visualizer demo for the triangle register, etc. and something to make it easier for the emulator to know that TEST mode needs to be enabled.