There’s also https://en.wikipedia.org/wiki/Kermit_(protocol)

(We used back in the day to move files between PDP11s and PCs - it was the original “anything to anything” file transfer program)

I still use it regularly in 2024 to load data onto embedded devices running U-Boot. It saves me a network cable if one is not otherwise required.

I just had to update the firmware my HF radio using xmodem protocol. Tons of modern ham radio gear still using serial data... even the modern ones that connect to your PC via USB, still just a USB->serial device built in.

U-Boot supports Zmodem ?

EDIT: actually not ZModem, but it supports X/YModem -- source code, despite the comment at its beginning, finally says "Sorry, zModem not available yet"

yes and also X/Ymodem, see source code: https://elixir.bootlin.com/u-boot/latest/source/common/xyzMo...

extremely useful feature (I used xmodem in the past, if I remember well)

Did not know that. Indeed it's very useful. Thank you!