Yesterday @ckrtech contacted me for insight on an issue he's having with Battlezone and his new RetroTINK 5X-Pro video upscaler. The picture is unstable, as you can see in the video he tweeted this afternoon:     I suspected it was generating an invalid VSYNC signal. From Stella Programmer's Guide, available at MiniDig, we know that VSYNC should last 3 scanlines:   So I used Stella to check it out. Sure enough, it was just over 2 scanlines long, and had a c