Posted by Brian Lewis on September 15, 1999 at 06:42:31:
In Reply to: arcadeos output resolution posted by scott oberg on September 14, 1999 at 01:00:16:
: I've noticed that, apart from the -incabinet=1 switch, arcadeos also allows one to change the NTSC scan rates. The defaults are 105 Horizontal and 4 vertical.
: My question is: What do these numbers mean? I've got reason to suspect that my monitor might be a little odd in its scan rates (although NTSC is a STANDARD, right?), and I want to play with these numbers in a meaningful way to test a hypothesis. Any suggestions?
: Thanks in advance.
The horizontal number is the number of character clocks
in the horizontal scan
(actuall - it's the total -5, just a quirk of VGA cards)
Basically -
the higher this number, the lower the hz. scanrate,
the lower this number - the higher the hz. scanrate.
The vertical number is the 8 least significant bits of the
vertical line total.
the higher this number - the lower the vertical refresh rate
the lower this numebr - the higher the vertical refresh rate
They're there to allow for small differences between
VGA cards/monitors etc.
If you think you've got a sync problem, I'd suggest
altering the horizontal number first.
ArcadeOS limits the range to something fairly safe,
so you damage anything by altering it.
The horizontal scanrate will also effect the vertical refresh rate,
so if you lower the scanrate, each line will take
longer to draw and the vertical refresh rate will drop.
same thing if you up the scanrate, the refresh rate
goes up as well
Brian
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