Today I learned that the original USB-A and USB-B connectors had this fundamentally different design to prevent people from using them to plug computer together and causing short circuits, as the ports back then weren’t able to detect whether there as a peripheral device or another host on the other end. Therefore the incompatible A and B connectors were introduced. And even while the short circuit problem was solved down the line, until USB-C for larger connectors there was no USB socket, that could do both, acting as host and as peripheral device. While this was already possible for mini-USB connectors, since the first version of the Mini-AB connector.

I came across this when checking a YouTube video by “Nostalgia Nerd” about why so many different USB cables exist, that was thrown into my feed today. It turned out to be quite interesting.