How does the VGA sequencer work?

[superfury]

Anyone knows how exactly the VGA sequencer takes all pixels in order from VRAM and passes them to the attribute controller?

I've gotten the attribute controller and DAC the sequencer in text mode working, but most graphics modes won't work fully (see below).

Current status of my emulator VGA:
- 256-color (8-bits color) mode seems to work.
- the interleaved shift (partly, although planes 2&3 give junk) works when planes 2&3 are masked off. Probably planes 2&3 aren't cleared properly.
- The monochrome modes give junk.
- 16-color modes should work, but don't work yet.)).