No, it's not. It's outdated. I'm just too slow.
It turns out that the output video DAC has different output impedance, and thus has a different amount of delay, and thus a different hue angle, as a function of the specific DAC tap that's being driven.Drag wrote: ↑Fri Aug 05, 2022 12:14 pm I think the hue of each color can be expected to be the same from PPU to PPU of the same region (NTSC or PAL), because the color subcarrier is completely digital. It is essentially a clock signal fed through a 12-step shift register, to create 12 phases of the same {color subcarrier frequency}mHz clock. The phase used for the colorburst reference, which determines what hue all the colors will have, is just one of the phases from the shift register all of the rest of the phases come from, so I'd expect that hues from PPU to PPU will be the same.
So even though digitally the angles are perfectly uniform divisions every 30 degrees, as the output gets brighter it gets slower and shifts hue.
NewRisingSun told me that as a rule-of-thumb, it's about 5 degrees hue per step brighter (the top 2 bits of the color number) on the 2C02G, and about 2.5 degrees on the 2C02E
I'm working on massaging the data in viewtopic.php?p=187234#p187234 to give more precise numbers
Ok, data massaged.
Relative to an arbitary 0 point,
2C02G:
$0x is about -8 to -9.3 degrees
$1x is about -13.7 to -15 degrees
$2x is about -20.7 to -22 degrees
$3x is about -24 to -25.2 degrees
Relative to a different arbitrary 0 point,
2C02E:
$0x is about 8.7 to 10.9 degrees
$1x is about 6.5 to 8 degrees
$2x is about 3 to 5 degrees
$3x is about 1 to 2.3 degrees
This is just one hue across a series - it's way too much data to do by hand.
ugh, one more edit: Capacitors! Not only will older capacitors add more uncorrelated noise, such as so-called "jailbars" and random-seeming noise, but they could add more correlated noise, changing how quickly the output can change - and thus the angles of the colors.