RedskullDC <redskulldc@oohay.moc.ua> wrote:
I can't tell you whether the hardware reads the SCB at the beginning of
the scan line or just after the previous one, but it is somewhere within
the horizontal blanking period. I think it also reads the palette data
during the horizontal blanking, so in principle you can have a different
16-colour palette for all 200 lines, even though there are only 16
palettes available.
I'm guessing that it reads the SCB then palette data on the negative
transition of the Horiz sync pulse, though it could be anywhere in the
front/back porch, horiz sync area.