> I'd like to say that I'm astonished that modern aircraft still use the 1553 bus...
What's wrong with 1553? It's reliable, battle-tested, and the latest revision C was published 28-Feb-2018. In contrast, the RS-232 PHY dates back to 1960, yet it's quite alive and well in modern commercial devices. As a consolation, be glad you've never had to deal with the monster that is STANAG 5516/MIL-STD-6016...if there was such a thing as a "modern" interface standard whose sheer page count (11,410 pages!) would make any sensible engineer reconsider future career prospects.