For anyone else curious the TLDR is that 240p is really 480i with tweaked timings so that the lines from the two interlaced frames strike the screen in the same

For anyone else curious the TLDR is that 240p is really 480i with tweaked timings so that the lines from the two interlaced frames strike the screen in the same place. This is also why a lot of old 240p consoles (NES/Master System through to PS1/N64/Saturn ) look even worse on modern TVs than you would expect them to - the TV tries to deinterlace the signal, but it's not really interlaced. With a 240p aware linedoubler converting your signal to 480p HDMI you can get much better results, and much lower latency.