> Yes.. to simulate a curved screen. On a curved screen, you can adjust things so that > the image is corrected to appear perfectly squared on a round tube using pincushion. > > However, most arcade monitors in the arcades were never adjusted like this. They > factory shipped them without pincushion adjusted... so the image lit up the entire > tube.
It's entirely possible to fill a rounded screen and display an image without any geometric distortion. Remember, CRTs were *completely* round until the mid-1950s (and "roundies" were made until ~1970 because they were cheaper to manufacture), and it's considered unusual if you can't adjust those sets to get perfect geometry, albeit with the corners missing.