The USB Implementers Forum (USB-IF) has published the specifications for USB4, building on the existing USB 3.2 architecture and based on the Thunderbolt protocol spec, and using the USB Type-C connection. USB-IF says USB4 is backwards compatible with USB 2.0, USB 3.2 and Thunderbolt 3, and will feature a maximum speed of up to 40Gb/s, twice the current 20Gb/s maximum.
Normally, once a spec is finalized it usually takes a year to see implementations in hardware, but what’s most interesting to me is that a cursory look makes it seem to essentially be a rebranding of Thunderbolt 3 (albeit as an open spec).
Yes, it seems to be exactly like that. <- EDIT: No, not really... :(
I think that this is good for Mac users because it basically leads to one single connection working across all computers, tablets and maybe even smartphones in the years to come.
The current Thunderbolt/USB situation is a mess. You have to be very careful to choose the right cable to get data from one device to another with fast speeds or you might end up with low speeds or just a “charging cable”. It is a complete mess: USB-C means nothing, it is just a connector and data-wise, it can mean anything, from USB 2 to 3 to 3.1 or whatever. Or it even can be Thunderbolt 3…
If eventually USB-C means USB 4 in all cases, we finally will be in a position, where everything just would work. Ok, I doubt it. But one can dream, I guess…
How would yet another spec change the situation that you neither can push 30Gbps through a 9ft long charging-only cable, nor 100W of power through a thin (= cheap) accessory cable that came with a cheap china gadget from AliExpress.
Sure, the dream would have been to only have one type of cable everywhere that could handle both with ease. Unless we either figure out new physics or would be willing to always pay a high premium and accept carrying around thick and heavy cables, this is unlikely.
Don’t get me wrong, I would have loved this myself. I guess the only thing that we can do is to educate ourself and the people around us.
You are right. My issue is that there is no way of knowing what a USB-C/Thunderbolt cable actually does when holding it in your hands. And for the normal user, the whole situation is a complete mess.
Because I am aware of the issues, I only use USB-C cables of up to 2m (approx. 6ft) that are capable of doing everything Thunderbolt 3 is capable of and AliExpress stays out of my house.
And to follow-up to my dream in the post above: I just read a German IT article. A translated excerpt:
Because of the lower basis speeds of USB, it is clear that it is not necessarily downwards compatible to Thunderbolt 3. This is not the only difference in comparison to Thunderbolt 3. USB 4 is using USB-C plugs and can be used for hosts to put Display Port signals through USB-C, but the alternative throughput of PCIe packets is optional only. Apart from that, USB 4 uses a different topology in comparison to Thunderbolt 3. Thunderbolt 3 can be used daisy-chaining multiple devices whereas USB 4 still needs the known hub tree structure.
So, basically, it stays the same: even USB 4 land will not become Thunderbolt 3 land. They will remain compatible to some degree, but not in every way.
So, we will keep living in connection chaos to some degree, even with some more years down the road with a USB-C plug… Oh well…
The thing is that the 2m cables might use the TB3 interface, but won’t reach the max speeds.
Once the 2016 MBPs hit the market, my initial idea was to get a small portable 13" and when at home hook it up with one cable to an eGPU and from their connect or daisy-chain to external storage, LAN, drive 4K displays (1 or 2). And have everything, especially the clunky and potentially noisy eGPU housing be hidden under my desk.
Then I found out that those cables can only be 0.5m long.
If you get a 1m TB2 cable the speed already drops down to 20Gpbs max.
What I meant to say is that I go for cables up to 2m that are technically able to deliver what Thunderbolt 3 can offer within the boundaries that are being dictated from physics and what not. And that the overall situation is frustrating. And that I hoped USB 4 to be the solution to the USB mess (USB-C cables with only USB 2 speeds which is just ridiculous).
