Meanwhile I have no idea what's going with this orange on 8565. I'm pretty sure that the square counts are correct. I guess the designers started off with something that more resembles the ratios on the 6569 but then had to adjust because the resulting colors were off?
Somehow I wish you just say that it's an error. But I also had a look on the die-shot and you are correct. Maybe just an individual error of that run of production?
In so many ways, the corrected cos value would make "sense". Color amplitude is adjusted to the other colors' common value and also the color angle will be the same as obviously the NMOS chips have.
Also if I use the corrected color angle (~128°), the comparison between "target" angles and measured values (vectorscope) looks so much more straight forward than when using the uncorrected orange value (~122°). Please see attachment.
There is in fact a patent from CBM (US4489284) that describes this circuit, more or less. (Could not add a link for some reason.)
Cool. Do you have an idea what it is for? Maybe to compensate the angle dependant ODD/EVEN color deviation (see 6569R5 diagram) and make the mix color much more fit the target angle? Also the snakes' color/burst ratio in HMOS-II seems similar like NMOS (~1.3), but the measured color amplitude of HMOS-II looks more like 1.0 of burst. So it's the aim of that magic part to do all this stabilizing?
You also had mentioned that the difference in HMOS-II colors is that they are always switched on. I don't understand what's the difference/effect for this. I have no clue about electronics basically. Always switched on would eliminate that parasitic phase errors of the sin/cos parts?
Could it be that the magic "stabilizing" circuit does something to the orange (because color angle somewhere near color burst angle?) so that they had to make this cos-snake-adjustment to finally get the target color angle and amplitude for orange? I just dont understand why just for the orange.