Originally Posted By Nathan Strum
How would you run the code on old hardware? A ROM swap of some sort?

Yep, it would be a ROM swap. There are 256 possible colors supported by the hardware. I would fill the screen with one color at a time so that it is the dominant signal. You would cycle through them by pressing a button. Then you'd need to measure the R,G,B voltage values at the RGB encoder board's outputs for each color.