240p video

In order to save costs and also to present a stable image on interlaced displays most games developed before the year 2000, and hence all the consoles and arcade games that played them, are rendered in a resolution around 320 pixels wide by 240 pixels high, commonly referred as 240p. This video mode is actually a hack on top of the NTSC standard, but it works on all SD displays without issues. The trick is to paint only even lines, and instead of painting the odd ones paint the even lines again. This is what causes our beloved scanlines on CRTs; they are actually part of the image.

Why does all this matter? Simple, this 240p video mode is not considered by displays since it is not part of the standard. Displays interpret it as if it were 480i video, generating video atrifacts and delay in the process.

In order to display a 240p signal in a progressive display without the delay needed to process 480i signals and without the artifacts introduced by incorrect processing, a video processor can be used. One such example is the XRGB, although there are many more options .

There is also a 240p test suite to evaluate how processors and TVs handle 240p video signals.