What to do monitors with about 15-16 kHz horizonal sync rate and 50-60 Hz horizonal rate ?
The monitors which use 15625 Hz or 15750 Hz horizonal sync rate are very similar to normal television are designed for viewing normal interlaced TV standard video at 50 or 60 Hz field rate. If you have this kind of monitor it might not be very useful as computer text display because you will need to use interlacing to get any usable resolutions (640×480 or 800×600). If you want to use theis monitor with your PC vga card then you first have to make the suitable connection between VGA card and the monitor. When you have made the connection you caa try to test the drivers made for VGA to TV converter circuit described at http://www.hut.fi/Misc/Electronics/circuits/vga2tv/index.html. Take also look at http://mameworld.retrogames.com/pc2jamma/phard5.html.
