The roots of this project go back to 2010
Here's Kat Manton's explanation of the Modeline timings she worked out.
"8.10" sets the pixel clock to 8.10 MHz
"664 680 752 800" configures horizontal timing and breaks down as follows:
664 - number of active pixels (i.e., the horizontal resolution)
680 - sync start
752 - sync end
800 - total line length.
(8.10 MHz / 800 is 10.125 kHz. Which is spot-on.)
"377 378 385 405" configures vertical timing and breaks down as follows:
377 - number of active lines (i.e., the vertical resolution)
378 - sync start line
385 - sync end line
405 - total number of lines
"-hsync -vsync interlace" are fairly self-explanatory
(from
https://www.vintage-radio.net/forum/...d.php?p=385733 post #18)
I presume Peter was working with the same figures when he designed his circuit,
but here's the thing,
I couldn't get an equal number of odd/even field broad pulses until I shortened the field sync interval by 1H, ie. 379-385
So my Modline became
Modeline "664x377_25 10.1kHz 50.0Hz" 8.100 664 680 752 800 377
379 385 405 interlace -hsync -vsync
I know Trevor was using this from the outset, but I'm wondering if Peter had to grapple with this.
It's something I've meant, to mention but haven't until now.