There are so many pixels in an HDTV image, and the arithmetic to compute them is so fast and so dense.  We’ve got extremely tiny integrated circuits today, with millions of transistors in a space smaller than your fingernail, but I got curious:  what if the transistor was never invented?

Here’s a spreadsheet, showing how it would work out.  Assuming you could actually build the things (that’s 45 billion vacuum tubes per TV set):

The electricity production of the entire planet today, about two trillion watts, would be enough to run

23 TV’s.

Here’s how I did it, if you’re curious: