1024x768 31khz AGA.. is it possible???

[Ilwrath]

As I understand how things work...  (And my understanding is limited to inventing a few custom original arcade screenmodes for MAME on CyberGraphX)

1024x768x31000(31KHz) = 24.38MHz
This is the required pixel clock.

Hmm...  As best as I can tell, the maximum AGA pixel clock is 28mhz.  28 > 24, so theoretically, this mode might be possible.  I have no idea how much (if anything) is lost to overhead.  All I really know is that I've never seen a driver do it.  If you manage to get it to work, let us know!


[EDIT: You may want to highly disregard the calculations above -- I think I did something very wrong.  I don't think it's that simple a calculation.]

[Ilwrath]

Alright.  Upon review, I really screwed this up.

I consulted with some X Screenmode Definition tutorials, and I'm ready for round 2.

Here's something closer to the truth:

1024x768.  First, you need to take into account overhead for the sync...
htotal ~= width*1.2
vtotal ~= height*1.1

So....
for total, we're looking at ~1230x850

now, for 31KHz horiz sync (31x1230), we need a minimum of a 38MHz pixel clock.  Well out of range of AGA.  Not gonna happen.

The driver that gave a 21KHz horiz sync (21x1230), would need a minimum of a 25.8mhz pixel clock.  Right at the ragged edge of the max value I found for AGA (28mhz).  I bet that's why it used such an odd value.