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USB4 technical specifications were published yesterday. Along with removing space in stylization (USB4 instead of USB 4), the new version offers double the speed of it’s previous versions. USB4 architecture is based on Intel’s Thunderbolt; Intel had provided Thunderbolt 3 to the USB Promoter Group royalty-free earlier this year.

Features of USB4

USB4 runs blazingly fast by incorporating Intel’s Thunderbolt technology. It allows transfers at the rate of 40 gigabits per second, twice the speed of the latest version of USB 3 and 8 times the speed of the original USB 3 standard. 40Gbps speeds, can example, allow users to do things like connect two 4K monitors at once, or run high-end external GPUs with ease.

Key characteristics as specified in the USB4 specification include:

Two-lane operation using existing USB Type-C cables and up to 40 Gbps operation over 40 Gbps certified cables

Multiple data and display protocols to efficiently share the total available bandwidth over the bus

Backward compatibility with USB 3.2, USB 2.0 and Thunderbolt 3

Another good news is that USB4 will use the same USB-C connector design as USB 3, which means manufacturers will not need to introduce new USB4 ports into their devices.

Why USB4 omits a space

The change in stylization was to simplify things. In an interview with Tom’s Hardware, USB Promoter Group CEO Brad Saunders said this is to prevent the profusion of products sporting version number badges that could confuse consumers. “We don’t plan to get into a 4.0, 4.1, 4.2 kind of iterative path,” he explained. “We want to keep it as simple as possible. When and if it goes faster, we’ll simply have the faster version of the certification and the brand.”

Is Thunderbolt 3 compatibility optional?

The specification mentioned that using Thunderbolt 3 support is optional. The published spec states: It’s up to USB4 device makers to support Thunderbolt. This was a major topic of discussion among people on Social media.

*Thunderbolt 3 (TB3) ; I forgot it got announced 6 hours ago that TB3 is now optional in USB4 spec despite it now being royalty free & vastly superior for it to be included. TB3 would enable @Alienware m15 & etc be plugged-in to a monitor like this & be charged simultaneously — Kevin Lozandier (@KevinLozandier) September 4, 2019

The USB Implementers Forum released a detailed statement clarifying the issue.

“Regarding USB4 specification’s optional support for Thunderbolt 3, USB-IF anticipates PC vendors to broadly support Thunderbolt 3 compatibility in their USB4 solutions given Thunderbolt 3 compatibility is now included in the USB4 specification and therefore royalty free for formal adopters,” the USB-IF said in a statement.

“That said, Intel still maintains the Thunderbolt 3 branding/certification so consumers can look for the appropriate Thunderbolt 3 logo and brand name to ensure the USB4 product in question has the expected Thunderbolt 3 compatibility. Furthermore, the decision was made not to make Thunderbolt 3 compatibility a USB4 specification requirement as certain manufacturers (e.g. smartphone makers) likely won’t need to add the extra capabilities that come with Thunderbolt 3 compatibility when designing their USB4 products,” the statement added.

Though the specification is released, it will be some time before USB4 compatible devices hit the market. We can expect to see devices that take advantage of the new version late 2020 or beyond.

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