As we look at the history of television, I wanted to tackle some of the frequently asked questions about the origins of the technology, as well as share some cool resources on movies and television.

One commonly asked question is why the early televisions had round screens. The television picture tube was a vacuum tube that contains one or more electron guns and a phosphorescent screen used to display images known as a cathode ray tubes (CRT).  When the original cathode ray tube was invented it was an experimental device, television was not yet developed. The natural shape of the cathode ray tube was round, as shown here in the diagram. The cheapest and easiest way to manufacture a CRT was to make it round.

The television picture is created on the surface of the cathode ray tube by drawing it rapidly line by line. The entire front area of the CRT is scanned repetitively and systematically in a fixed pattern. Before 1940 there was no standard in the United States for how the picture was created electronically using the cathode ray tube.

In 1940 the Federal Communications Commission (FCC) established The National Television System Committee (NTSC) to resolve the conflicts that were made between companies over the introduction of a nation wide analog television system in the United States.  The NTSC standard selected 525 scan lines, an aspect ratio of 4:3, and frequency modulation (FM) for the sound signal. The number of 525 lines was chosen as a because of the limitations of the vacuum-tube-based technologies of the day.