Color TV Porthole sets?

[VintagePC]

Originally Posted by old_tv_nut

Picture height and width was not very well regulated on tube sets, so the wise assembly line or serviceman would set them at least 10% over to avoid complaints about black edges on the screen.

Not just that but a lot of gear adds even more overscan these days... For example, I have a Mythtv-DVR wired to the satellite box here - If watching normally, the station "bug" is in the lower left corner of the tube... but if watching a recorded show there's a good 1-2" extra of picture around it that the tuner grabs but the TV never shows.