Dial Up. Yeah I know the sound and I know the time it took to load anything with. But it’s something I won’t ever miss having. I would much rather be on a 1MB connection if I had to choose between that or dial up ever again. I also hated how easy it was to be kicked off, if anyone called the phone, you were off it in seconds.
Barely relativistic: 10 - 20% of speed of light. But I agree, from technology point of view, that was very cool.
One type of CRT I miss is monochrome vector CRT. This is where the image was drawn, as opposed to rastered from pixels. Although, with “retina” displays, this became less important, it was still cool technology.