https://www.instructables.com/Video-Trigger-for-Retrocomputers-Using-TMS99282912/
Video Trigger for Retrocomputers Using TMS9928/29/128/129 VDP : 5 Steps (with Pictures) -...
Video Trigger for Retrocomputers Using TMS9928/29/128/129 VDP: My oscilloscope wouldn't trigger relibly on the video signal from my TMS9128 VDP, so I made this...