I was looking into rgb mods for the intellivision and besides the RetroRGB mod kit there isn't much available for ntsc models. I discovered a pal mod circuit here which requires 3 bits for red, green and blue, which ntsc models don't have. Instead, ntsc models have a 4bit code (one nibble for each background color) and the AY-3-8915 does all the color processing. My goal is to design a decoder circuit which takes the 4bit color code and convert it into the 3 bits per color rgb code. To do this I need to know the 3bit rgb codes for each background color so I can design the decoder.
Does anyone have a pal intellivision service manual with the rgb color table?
Would someone with a pal intellivision be willing to open it up and measure the rgb bits on the LM1886 for each background color? I have included a test rom and truth table for anyone willing to help me out.