The USB Promoter Group is hard at work developing the USB4 specification. We met with them at Computex this year, and the good news is that the spec is in its 0.96 version and things are proceeding quickly. The group believes that retail products featuring USB4 will be available by the end of 2020.

Update 16/6: The current USB4 spec is at 0.96.

Being based on Thunderbolt 3 technology and offering up to 40 Gbps bandwidth, USB4 promises to be more than that. In fact, so much more that the USB Promoter Group is considering a new logotype and branding scheme. The current one is already complex enough, so expect some kind of simplification on that front. Meanwhile, USB4 will be backwards compatible with existing USB Type-C devices.

When it comes to availability, USB-IF seems to be optimistic that the specification will be finalized this Summer and actual USB4-supporting devices will be available by the end of 2020. Since Intel knows how to build Thunderbolt 3 controllers, it will certainly use its expertise developing USB4 controllers eventually.

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  • TheUnhandledException - Thursday, June 13, 2019 - link

    There is no difference between usb 3.1 and usb 3.0 except a new 10 Gbps mode likewise with usb 3.2 adding a 20 Gbps mode.
  • repoman27 - Thursday, June 13, 2019 - link

    I completely understand where you're coming from, but a lot of what you're saying is misinformation that was propagated by the tech media echo chamber.

    Going back to my original assertion, the version numbers are only the version of the specification, which itself is a document distributed in pdf format intended for licensees building USB enabled devices. The working group makes some engineering changes, adds a few new features, and then puts out a new release with an incremented version number. The USB 3.1 specification is the USB 3.0 specification plus ECNs and the addition of the new Gen 2 PHY—90% of the text remained the same. Once 3.1 was released, the USB-IF deprecated USB 3.0 because licensees should all be referring to the new version not the old one from now on. This is like when Apple stops signing iOS 12.2 following the release of 12.3 and customers can no longer download or downgrade to previous versions. This is essentially the way *all* interface specifications work, not just USB.

    The reason why manufacturers know that that their USB 3.0 devices are most likely 3.1 or 3.2 compliant is because nearly 100% of the text of the USB 3.0 specification is included with only very minor changes in both the 3.1 and 3.2 specs, and 100% of the new features are optional. From the very beginning the USB-IF let everybody know that USB 3.0 was not going to be a one and done situation. The industry was stuck at USB 2.0 performance levels for way too long, and therefore, not only would 3.0 be a massive leap forward, but it would also be extensible through updates at regular intervals.

    From a licensing and maintenance point of view, the USB-IF is following the only sane path. Yet everyone on teh internets desperately wants specification version numbers that fully determine device capabilities. Once you include even a single feature in a spec that isn't mandatory, that idea goes straight out the window. Once you build an interface based on multiple specifications with lots of optional features in order to address a market of several billion devices, creating a version number that uniquely identifies each permutation would be ludicrous.

    With USB, most people don't just want to know the signaling rate, they also want to know which style of plug / receptacle is being used and what the power capabilities are. If a device is advertised as "USB Type-C, 5 Gbit/s signaling, 60 W source/sink power delivery," you probably know everything you need to without including version numbers for a single one of the three specifications referenced. And none of those version numbers would have pinpointed the exact device capabilities anyway.

    The Gen X and Gen X x Y nomenclature does not replace the specification version numbers, it's simply how the PHYs were referred to within the USB 3.1 and 3.2 specifications themselves. USB 3.1 introduced a new PHY with different capabilities that could be implemented alongside the original one. The engineers referred to these PHYs as Gen 1 and Gen 2. USB 3.2 introduced channel bonding in the form of dual-lane operation. Now you could have either PHY operating as an x1 or x2 link. It's a little unfair to fault the engineers for using the same terminology as every other engineer ever in the history of personal computer I/O interfaces. I will agree that the USB-IF promoting this terminology for use in public facing materials was ill advised. However, it would seem perfectly suited for the readers of sites like Anandtech, who actually have the desire to do a deep-dive and embrace the terminology used by the engineers themselves.
  • MarcusMo - Saturday, June 15, 2019 - link

    These couple of posts were some of the best I’ve read on Anandtech in a long while. Thank you!
  • Herbertificus - Sunday, June 30, 2019 - link

    I swear to God, I have never in my life seen so much mental masturbation as I have in this comment thread.

    First of all, Lord Of The Bored is exactly correct and Refluxman27 seems to be a good example, like Paul Krugman, of someone who's educated beyond his intelligence.

    The Implementors' Forum is attempting to maintain two parallel naming schemes -- one that's numerical and is therefore IMMEDIATELY and universally intuitive to anyone on the planet who is at least 4-years-of-age, and another with proper nouns constructed of superlatives stacked on top of superlatives, with a few pluses and "gens" thrown in to make things even "clearer." Now, I'm not exactly stoopid, but for the life of me I cannot remember which of the superlative combinations is better/higher/faster than the other superlative combinations.

    But it is damned easy to see that 3.2 should be faster/better/more advanced than 3.1, which is likewise faster/better/more advanced than 3.0, which is likewise . . . .

    And because USB specifications are always backward compatible, they are all EQUALLY backward compatible, so backward compatibility is not a distinguishing feature between the different versions . . . but forward compatibility is. There's every reason always to purchase the product that is certified to the highest numerical spec because it will be the most future-compatible and future-proof, and NO REASON to purchase a product with a lower spec. It doesn't get any more simple or intuitive for the buying public than this simple numerical progression nomenclature. Nor can a nomenclature scheme be more UNintuitive and absolutely useless than the IF's moronic proper noun scheme which, as Sir Lord Bored noted, has been roundly rejected by everyone in the known universe. Every DAMN time I'm in Worst Buy picking up a hard drive or looking at the USB ports on a laptop, I'm saying to myself, "OK, is UltraUberSuperDuperSpeed the same as 3.0 or 3.1 or 3.2 Gen1 or Gen2 ? ? ?" . . . And I'm saying that to myself because I already understand what 3.0 and 3.1 and 3.2 mean. What's more is that even someone who knows nothing about USB and isn't even all that bright -- say, Paul Krugman -- even that person could easily pick out which of the three is the latest and greatest.

    Sorry, but Monsignor Lord Bored is right. And all the crap about "spec this" and "spec that" and "vendor this" and "vendor that" is just useless claptrap. THE ONLY TWO THINGS THAT MATTER are that the labeling is honest and that THE CONSUMER can understand that labeling INTUITIVELY, without having to do RESEARCH to decipher the inverted pyramid of accumulating superlatives.

    And whoever it was on the IF who thought up the "Gen #x#" crap ought to be taken out behind the barn and shot. Each successive bump in speed should get it's own numerical I.D. -- it's that simple.

    One other UltraUberSuperDuper error the IF is making is NOT requiring all C-ports to be powered by a 3.2 chip and to comply with the 3.2 spec. It is nothing less than moronic for a manufacturer to be able to put a C-port in their product that is merely 2.0 or 3.0 compliant. Yes, I know the argument that the physical port and the protocol spec are two separate things, but the C-port is a major break -- a fundamental change in the USB world, and that new physical standard should ALWAYS be associated at least with the specification which was a major leap forward at the same time the port was introduced. THE WHOLE POINT of buying products that specifically have the C-port is to get the latest jump in speed. Otherwise there IS no point in getting C.

    Makes me wonder whether Paul Krugman works at the IF.

    My one complaint that no one has brought up is just that the product world is so unbelievably slow in adopting the new ports and the new specs. As I write this in June of 2019, I STILL can't buy an external Western Digital 8TB harddrive that has a C-port. They do have a 4TB 2.5" drive -- the "Passport" -- that has a C-port, but not a big drive that has a C-port. What gives ? Have you looked for a thumb drive that is USB-C ? Rotsa ruck with that. Even more difficult when you do find a thumb drive that's C . . . try to figure out WHICH VERSION of USB it's compliant with. The CIA or the KGB might know, but no one else does.

  • mooninite - Wednesday, June 12, 2019 - link

    Is this going to finally combine Thunderbolt into USB? Who even has Thunderbolt devices (outside of Apple)?
  • TheUnhandledException - Wednesday, June 12, 2019 - link

    My company computer dock (lenovo) is TB3. Wonderful. One capable to support three 1600p monitors plus ethernet, plus peripherals and charge the laptop.
  • Diogene7 - Wednesday, June 12, 2019 - link

    If I am not sure but I read tha the 2019 Intel 10nm IceLake processors will natively support Thunderbolt 3, and it is likely that all future Intel processors after that will as well.

    It means that from H2 2019 and going forward, all new computers based on 10nm processors or newer will come equipped with Thunderbolt 3.

    So I would think that Thunderbolt 3 USB-C connectors will soon become more widespread on computers, slowly replacing legacy USB-A connectors.

    It may have the potential to replace all other connectors (power supply, USB-A, HDMI, Ethernet,...) by one single universal connector and I do really hope it will be the case !!!
  • Xajel - Wednesday, June 12, 2019 - link

    Well, TB3 is already finished years ago, so what exactly they're working on? are they going to redesign TB3 with USB "how it works"? or it just a new implementation based on TB3.

    I just hope naming will be human readable, unlike the current mess.
  • dontlistentome - Wednesday, June 12, 2019 - link

    USB is different to TB3 in terms of PCIe, protocols etc - hopefully USB4 will keep the ability to use hubs etc (as TB3 hubs are way expensive because of the PCIe bits).

    USB4 replacing sata for HDD/SSD connectivity at the consumer end would be great - single cable signal and power, dirt cheap hubs instead of $$$ sas cards if you need lots of ports for a NAS, same drive uable internally or externally with the same cable. Suspect latency might not be optimal for boot SSDs but for spinning rust or general file storage most users probably wouldn't notice any difference.
  • repoman27 - Wednesday, June 12, 2019 - link

    To date, Thunderbolt has only supported daisy chain topologies and not tiered star like USB. The term "Thunderbolt hub" as it is currently used is a complete misnomer when compared to hubs in the USB or Ethernet sense. They're really only single-port or dual-port (daisy chainable) Thunderbolt docks which happen to provide connectivity in the form of additional ports supporting other protocols.

    USB4 will almost certainly be more complex (read: expensive) than USB 3.2, but it won't be adopted for all applications. Just like USB 2.0 lives on for mice, keyboards, and a billion other things, USB 3.2 will probably be around for a long time to come yet. But because backwards compatibility is a hallmark of all of the USB protocols, as long as we get USB4 host ports wherever it matters, the devices can use whichever version makes sense for their particular price point.

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