Signals merging circuit - request for help

[retromaniak]

Hi, I recently came across a very old syncdoubler project for the Amiga on the network. His problem was that he was only able to display half the image at a time. However, 25 years have passed and the technology is incomparably more developed. the question is, does it exist or would it be possible to design a system that would cut information about breaking the line and the end of drawing the frame from one of the generated signals, and then connect those signals together?

[VajSkids Consoles]

https://www.youtube.com/watch?v=5daXoHw1s4g
???