oh-ho, quite right on both counts
You get tricked by using (or writing as in my case
emus, where by the population of the framebuffer and the re-rendering of it are separate stages and can cheat .. and here, you don't get the luxury so much.
In NTSC mode (when e.g. using an amercian TOS) the screen refresh rate is 60Hz. This is directly compatible with most VGA screens.
The Atari ST core provides a switch via the on-screen-display (OSD) to allow a 50Hz output or to tweak the 50Hz signal into a 56Hz signal. The downside of this is that this frequency is also available as a signal to generate software timings and some software may not work properly with 56Hz instead of 50Hz. The same video timing is used for both color video modes (ST mid 640x200 and ST low 320x200).
The Atari ST core on the MIST thus supports four video timings:
monochrome 640x400 at 72Hz (HIREZ)
color 640/320x200 at 60Hz (NTSC),
color 640/320x200 at 50Hz (PAL), and
color 640/320x200 at 56Hz (modified PAL).
I'll give this a shot soon, thanks!
I actually ripped my ROM out of a ST Book (which is annoying as poo, since it has no floppy, so I yanked the hdd out; at the time, no ultra-satan ..) -- I'll go find one of my US ROM rips, or just find a damned TOS file
(offhand, what does EmuTOS identify as, I wonder.. though sort of irrelevent, since EmuTOS won't typically play any games.)