Reply to comment

The CGA monitor I used for this project only needed a few pins shorted out on the monitor cable to make the screen solid with a particular color. (Shorting the intensity pin with a color pin.) Upon recieving an intensity signal, the CGA monitor itself appears to drive the display with hsync and vsync signals. This is possible with a fixed frequency monitor (one that only runs at a single, set resolution.)

This would not work on the typical VGA monitor, most of which are designed to run off several different possible resolutions (multisync). This kind of monitor expects to be driven by a proper signal before anything will display on the screen. There are a few ways around this: You could make a circuit to supply phony 640x480 sync signals at the VGA port input, then set a color pin to 1V (or whatever it is for max intensity). Alternatively, you could drive the coil directly with a sawtooth wave, while also finding a way to activate the electron gun directly.

If I ever get around to doing this with a VGA multisync monitor, I'll be sure to post my results here.