On Fri, Feb 28, 2025 at 03:23:07PM -0500, D. Hugh Redelmeier via talk wrote:
<https://everything.explained.today/USB4/>
Did you know it is USB4, not USB 4? But USB 2.0, not USB2?
I now have two Macs that I want to connect via Thunderbolt 4. I don't know how to tell if a particular cable will work.
Oh yes USB is complicated. USB4 ports are required to implement USB 2.0, USB 3.2 (but only 5 and 10Gbps are required, 20Gbps is optional), and DP Alt mode supporting at least DP 1.2 for 4K60. Must use USB-C connector. USB 2.0 is the newest version of the original USB with 4 wires (+5V, ground and +/- data pins) with the 1.5, 12 and 480Mbit speeds. USB 3.2 is the newest USB 3.x standard covering the new pins that were added allowing full duplex at higher speeds covering the 5, 10 and 20 Gbps. Then there are the thunderbolt supersets on top of USB4 (apparently USB4 hubs must support thunderbolt, but hosts and devices don't have to). And of course the interesting tunneling abilities of USB4 to allow carrying display traffic and network traffic and various other interesting things. USB started out simple, but sure isn't anymore. -- Len Sorensen