Editing USB (section)

=== USB4<span class="anchor" id="USB4"></span>===
{{Update|section|date=August 2024|reason=Incomplete, erroneous and not up-to-date; e.g. lacks differences between USB4 first version and 2.0. Applies also to main article.}}
{{main|USB4}}
[[File:Certified USB4 40Gbps Logo.svg|thumb|upright=0.5|Deprecated ''Certified USB4'' logo]]

The USB4 specification was released on 29 August 2019 by the USB Implementers Forum.<ref name=USB4Spec>{{Cite web |url=https://www.usb.org/sites/default/files/USB4%20Specification.zip |title=USB Promoter Group USB4 Specification |date=29 August 2019 |website=USB Implementers Forum |access-date=30 August 2019 |archive-date=13 February 2021 |archive-url=https://web.archive.org/web/20210213071426/https://www.usb.org/sites/default/files/USB4%20Specification.zip |url-status=live}}</ref>

The USB4 2.0 specification was released on 1 September 2022 by the USB Implementers Forum.<ref>{{Cite web |title=USB Promoter Group Announces USB4 Version 2.0 Specification defines delivering up to 80&nbsp;Gbps over USB Type-C |url=https://www.usb.org/sites/default/files/2022-09/USB%20PG%20USB4%20Version%202.0%2080Gbps%20Announcement_FINAL.pdf}}</ref>

USB4 is based on the [[Thunderbolt 3]] protocol.<ref>{{Cite web|url=https://arstechnica.com/gadgets/2019/03/thunderbolt-3-becomes-usb4-as-intels-interconnect-goes-royalty-free/|title=Thunderbolt 3 becomes USB4, as Intel's interconnect goes royalty-free|last=Bright|first=Peter|date=4 March 2019|website=Ars Technica|access-date=4 March 2019|archive-date=13 February 2021|archive-url=https://web.archive.org/web/20210213071427/https://arstechnica.com/gadgets/2019/03/thunderbolt-3-becomes-usb4-as-intels-interconnect-goes-royalty-free/|url-status=live}}</ref> It supports 40&nbsp;Gbit/s throughput, is compatible with Thunderbolt 3, and backward compatible with USB&nbsp;3.2 and USB&nbsp;2.0.<ref>{{Cite web|url=https://www.cnet.com/news/usb4-marries-thunderbolt-3-for-faster-speeds-and-smarter-transfers/|title=USB4 Marries Thunderbolt 3 for Faster Speeds and Smarter Transfers |last=Grunin|first=Lori|website=CNET|date=4 March 2019|access-date=4 March 2019|archive-date=4 March 2019|archive-url=https://web.archive.org/web/20190304232454/https://www.cnet.com/news/usb4-marries-thunderbolt-3-for-faster-speeds-and-smarter-transfers/|url-status=live}}</ref><ref>{{Cite web|url=https://www.pcmag.com/news/366931/thunderbolt-3-merges-with-usb-to-become-usb4|title=Thunderbolt 3 Merges With USB to Become USB4|last=Brant|first=Tom|date=4 March 2019|website=PC Magazine|access-date=4 March 2019|archive-date=5 March 2019|archive-url=https://web.archive.org/web/20190305024642/https://www.pcmag.com/news/366931/thunderbolt-3-merges-with-usb-to-become-usb4|url-status=live}}</ref> The architecture defines a method to share a single high-speed link with multiple end device types dynamically that best serves the transfer of data by type and application.

During [[CES 2020]], USB-IF and Intel stated their intention to allow USB4 products that support all the optional functionality as [[Thunderbolt 4]] products.

USB4&nbsp;2.0 with 80&nbsp;Gbit/s speeds was to be revealed in November 2022.<ref>{{Cite web|url=https://www.pcgamer.com/usb4-version-20-with-80gbps-speeds-is-coming/|title=USB4 Version 2.0 with 80Gbps speeds is coming|last=Szewczyk|first=Chris|date=September 5, 2022|website=PC Gamer|access-date=September 20, 2024}}</ref><ref>{{Cite press release|url=https://www.usb.org/sites/default/files/2022-09/USB%20PG%20USB4%20Version%202.0%2080Gbps%20Announcement_FINAL.pdf|last1=Saunders|first1=Brad|last2=Balich|first2=Joe|title=USB Promoter Group Announces USB4® Version 2.0|date=September 1, 2022|publisher=USB Implementers Forum|location=Beaverton, OR, USA|access-date=September 20, 2024}}</ref> Further technical details were to be released at two USB developer days scheduled for November 2022.<ref>{{Cite press release|url=https://usb.org/sites/default/files/2022-10/USB-IF%20USB%2080Gbps%20Announcement_FINAL_v2.pdf|last=Balich|first=Joe|title=USB-IF Announces Publication of New USB4® Specification to Enable USB 80Gbps Performance|date=October 18, 2022|publisher=USB Implementers Forum|location=Beaverton, OR, USA|access-date=September 20, 2024}}</ref>{{update-inline|date=October 2024}}

The USB4 specification states that the following technologies shall be supported by USB4:<ref name=USB42Spec/>
{{clear}}
{| class="wikitable"
|-
! rowspan="2" style="width:240px" | Connection
! colspan="3" | Mandatory for
! rowspan="2" | Remarks
|-
! style="width:50px; text-align:center"| host !! style="width:50px; text-align:center"| hub !! style="width:50px; text-align:center"| device
|-
| '''USB 2.0''' (480&nbsp;Mbit/s)|| {{yes}} || {{yes}} || {{yes}} || Contrary to other functions – which use the multiplexing of high-speed links – USB 2.0 over USB-C utilizes its own differential pair of wires.
|-
| '''Tunneled USB 3.2 Gen 2×1''' (10&nbsp;Gbit/s)|| {{yes}} || {{yes}} || {{no}} ||
|-
| '''Tunneled USB 3.2 Gen 2×2''' (20&nbsp;Gbit/s)|| {{no}} || {{no}} || {{no}} ||
|-
| '''Tunneled USB&nbsp;3 Gen T''' (5–80&nbsp;Gbit/s)|| {{no}} || {{no}} || {{no}} || A type of USB&nbsp;3 Tunneling architecture where the Enhanced SuperSpeed System is extended to allow operation at the maximum bandwidth available on the USB4 Link.
|-
| '''USB4 Gen 2''' (10 or 20&nbsp;Gbit/s) || {{yes}} || {{yes}} || {{yes}} || rowspan="2"| Either one or two lanes
|-
| '''USB4 Gen 3''' (20 or 40&nbsp;Gbit/s) || {{no}} || {{yes}} || {{no}}
|-
| '''Tunneled DisplayPort 1.4a''' || {{yes}} || {{yes}} || {{no}} ||The specification requires that hosts and hubs support the DisplayPort Alternate Mode.
|-
| '''Tunneled PCI Express 3.0''' || {{no}} || {{yes}} || {{no}} || The PCI Express function of USB4 replicates the functionality of previous versions of the [[Thunderbolt (interface)|Thunderbolt]] specification.
|-
| '''Host-to-Host communications''' || {{yes}} || {{yes}} || {{n/a}} || A LAN-like connection between two peers
|-
| '''Thunderbolt 3 Alternate Mode''' || {{no}} || {{yes}} || {{no}} || Thunderbolt 3 uses cables with USB‑C plugs; the USB4 specification allows hosts and devices, and requires hubs, to support interoperability with the standard using the Thunderbolt 3 Alternate Mode (namely DisplayPort and PCIe).
|-
| '''Other Alternate Modes'''|| {{no}} || {{no}} || {{no}}
| USB4 products may optionally offer interoperability with the [[HDMI]], [[Mobile High-Definition Link|MHL]], and [[VirtualLink]] Alternate Modes.
|}

==== September 2022 naming scheme ====
[[File:USB 2022 September naming scheme.svg|thumb|upright=2.8|An overview of USB naming scheme that was put in place in September 2022
<br />(A mix of USB specifications and their marketing names are being displayed<br />because specifications are sometimes wrongly used as marketing names.){{Disputed inline|File:USB 2022 September naming scheme.svg|for=USB4 20&nbsp;Gbit/s does not exist; USB4 2×2 is not interchangeable with USB 3.2 2×2 as<br />indicated by the logo; logos for USB 3.x and USB4 are different.|date=July 2023}}]]
Because of the previous confusing naming schemes, USB-IF decided to change it once again. As of 2 September 2022, marketing names follow the syntax "USB&nbsp;''x''Gbps", where ''x'' is the speed of transfer in Gbit/s.<ref name="USB data performance language usage 2022-09">{{Cite web|title=USB Data Performance Language Usage Guidelines from USB-IF|url=https://usb.org/sites/default/files/usb_data_performance_language_usage_guidelines_september_2022.pdf|website = USB Implementers Forum | access-date=2 September 2022|archive-date=1 October 2022|archive-url=https://web.archive.org/web/20221001115816/https://www.usb.org/sites/default/files/usb_data_performance_language_usage_guidelines_september_2022.pdf|url-status=dead}}</ref> Overview of the updated names and logos can be seen in the adjacent table.

The operation modes USB&nbsp;3.2&nbsp;Gen&nbsp;2×2 and USB4&nbsp;Gen&nbsp;2×2 – or: USB&nbsp;3.2&nbsp;Gen&nbsp;2×1 and USB4&nbsp;Gen&nbsp;2×1 – are not interchangeable or compatible; all participating controllers must operate with the same mode.