[gzalo]

> Then you implement auto crossover detection, dwhich had been around for years

Mdi-x/auto crossover for ethernet was introduced in 1999, that is after USB (1996) was designed, not sure of the technique was known at that time

[userbinator]

You can't do "auto crossover" with USB because it needs to distinguish between D+/D- for speed selection.

https://electronics.stackexchange.com/questions/73295/in-a-u...

It works for Ethernet because the transmit and receive lanes are separate, but with USB, there's only one pair used for both directions.

[ilyt]

It doesn't need to.

It chose to. They could just use different way to do it. Like, I dunno, a single packet of negotiation in slow mode...

[dboreham]

There were auto-crossover RS-232 boxes going back deep into the 1980s.

[sitzkrieg]

with baud rate detection to boot (down the line)

[crote]

Not really relevant.

Ethernet needs crossover because it has dedicated transmit/receive pairs, but USB 1.x/2.0 uses a single wire pair for both tx & rx. Ethernet crossover is pretty much identical to serial null modem cables, and those were around for a few decades by then.

USB "crossover" of the single differential wire pair would be an inversion of 0 and 1. Pretty trivial to do once you figure out a way to communicate crossover or not.