Back in Days of Olde, when Men were Bold, and computers used lots of tubes (usually dual triodes, like 12AT7s, etc) and clock speeds were measured in Kilocycles.

Yeah, the picture looks kinda weird, it's a 3-D photo, one needs those funky cheap cardboard "monster movie" glasses with the red and green plastic lenses.

I've found that I can also get the 3D effect by slightly crosing my eyes, and looking at it from the correct distance - this will vary by individual. It doesn't work for everybody, but it's worth a try.

The tubes were generally pulled out and replaced after a few hundred hours' operation. Tubes don't like to be run with full plate voltage and no plate current, this can strip the cathodes, and reduce the emissions. Later years there were special "computer tubes" designed which overcame this problem, and they also work as excellent quality and very reliable audio tubes.