rmay635703 wrote on 2022-10-22, 12:50:
What is the pixel clock? vsync and hsync matter less than the pixel clock (even though you might get a rolling image it at least won’t explode)
The pixel clock doesn't matter at all, it just determines how wide pixels are. Of course, the pixel clock combined with the number of pixels per line (including the blanking time) determine the horizontal frequency. This is the most important timing parameter , because the high voltage generation circuit and the horizontal deflection circuit are designed around this frequency. Especially in fixed-frequency monitors, the design is often resonant, and even worse: There are some monitors that might break if the horizontal frequency is too low, because the deflection circuit is overdriven in that case. Incidentally, the original IBM MDA monitor is one of these rare beasts. That's why connecting a MDA monitor to an unknown signal that might be at CGA frequencies is a dangerous suggestion.
vsync mismatch also is harmless, it will just cause a rolling image, just as you describe.