Calamity of ArcadeControls report this patch works amazingly well with 31.5Khz CRT's. It produces the proper 240p 60Hz effect when running 240p 120Hz on 31.5Khz CRT's, while having less input lag! (Partially compensates for the mandatory input lag caused by the MAME frame buffer)
Running at 120 Hz has saves half a frame of input lag (8.33ms) over 60 Hz, a big win for Street Fighter and other fast-reaction button-mash games! Doing the black frame insertion masks the second repeat of a refresh, giving the proper 60fps@60Hz effect, while keeping the reduced input lag of 120Hz!