Hi all,

I wonder if there's anybody with an IBM VGA and a compatible oscilloscope, who can make some measurements? I suppose that any adapter known to be sufficiently VGA-compatible is ok, but please mention that such an adapter is used if that's the case.

Explanation:
There's been some recent work on an overscan border patch for DOSBox, see VIDEO - Overscan border (SDL1).
Sadly, as expected, I lack access to real hardware. Furthermore, unless I've done a silly mistake (which is a possibility with very great chances), looks like there is something not making sense in regards to video mode 0Dh on the VGA (320x200, double-scanned to 320x400, 16 colors, ~70.086Hz). Basically, according to a few calculations of mine, the horizontal retrace period appears to end at the very end of the scanline, if not one character later.

So, maybe some measurements with a device like an oscilloscope can give some light on the topic, possibly not just for this very specific mode.

Thanks in advance!
NY