Let's say you have an old VGA monitor, it needs 4 things: Red, Green, Blue, Sync And you need to deliver them at a steady pixel clock rate. Horizontal sync i

Let's say you have an old VGA monitor, it needs 4 things: Red, Green, Blue, Sync And you need to deliver them at a steady pixel clock rate. Horizontal sync is between each scanline, and Vertical sync is between each frame. There are official standards to follow here, with things defined such as voltage ranges for RGB, voltage levels for Sync, "Front Porch" and "Back Porch" (how much blank space you have before and after Sync), horizontal frequency, vertical frequency (refresh rate), etc, etc. Look for a video on Youtube called "The world's worst video card" for an example of constructing such a circuit.