A brief guide to USB 4 for Mac and iOS users

The USB Promoter Group has announced the next-generation USB-4 standard. This will provide a range of benefits for most computer users, including those on the Apple platform.

What are they saying?

The USB4 architecture is based on the Thunderbolt protocol specification recently contributed by Intel Corporation. It doubles the bandwidth of USB and enables multiple simultaneous data and display protocols.

“The primary goal of USB is to deliver the best user experience combining data, display and power delivery over a user-friendly and robust cable and connector solution,” said Brad Saunders, USB Promoter Group Chairman. 

Why does USB 4 matter?

Apple’s decision to use USB-C on iPad Pro and current Macs means the company has been able to get rid of a range of interconnects in order to support just one standard that can handle power, data and displays.

USB 4 builds on this. You can use it to share a single link with multiple types of device. The specification is also compatible with existing USB 3.2, USB 2.0 and Thunderbolt 3 hosts.

This means that while older USB systems won’t see any speed benefits, they should work with the new interface. If you use a USB 4 device you should see real performance gains.

What sort of performance gains can we expect?

USB 4 doubles bandwidth and will deliver up to 40Gbps when used with 40Gbps-certified cables.

To put this into perspective, USB 1.1 offered up to 12Mbps; USB 2 delivered up to 480mbps; USB 3 provides 5gbps.

These speeds translate into real benefits: data transfers are faster, video resolution on external monitors potentially higher, backups will be quicker and movie editors will see even less wait ingesting even huge movie files. You’ll even be able to connect an eGPU to your computer over USB 4.

What about USB-C?

USB-C is a peer player in the new USB4 standard.

For example, as well as two-lane operation and compatibility, you will also see an updated USB-C spec published alongside the final USB 4 spec.

The new USB-C spec will be all about ensuring the two interconnects work well together.

“The release of an updated USB Type-C Specification will be made to comprehend USB4 bus discovery, configuration and performance requirements,” the USB Implementer’s Forum said.

We don’t yet know if the final standard will allow users to connect 4K monitors at 60Hz using DisplayPort over USB-C, for example.

What about Thunderbolt?

Apple worked hand-in-hand with Intel on the development of Light Peak tech, which eventually became Thunderbolt/Lightning.

Thunderbolt has now been made available to the USB Promoter Group, which means it will be a core component of USB 4.

Intel has also agreed to let companies outside of the USB Promoter Group use the Thunderbolt specification on a royalty-free basis.

In other words, it will become pervasive. Intel already claims over 400 PCs ship with Thunderbolt, including almost every available Mac.

It will be up to hardware makers to field support for Thunderbolt within their USB 4 implementations, so you should check the small print if you want to use a Thunderbolt device with a USB 4 computer.

What did Intel say about Thunderbolt?

“Releasing the Thunderbolt protocol specification is a significant milestone for making today’s simplest and most versatile port available to everyone. This, in combination with the integration of Thunderbolt 3 into upcoming Intel processors is a win-win for the industry and consumers,” said Jason Ziller, general manager, Client Connectivity Division at Intel.

Reading between the lines, this means Macs running Intel chips can expect to see even better performance as integration with Intel chips appears. Assuming Apple sticks with Intel chips, of course.

Will USB 4 cables be expensive?

USB-C cables pack an awful lot of silicon inside. Shorter (up to 0.8m) USB 4 cables will (apparently) be cheaper, passive cables. Longer cables will need to be active cables, which means they may cost.

What about USB PD?

We’re told that all USB 4 connections will require USB-C connectors and will support USB PD.

Was Apple right to choose USB-C?

It looks like it. There has been pressure on Apple to move to USB-C across all its devices. Announcement of USB 4 and news of its integration of Thunderbolt/Lightning makes this much less likely. I think Apple is now far more likely to move to USB 4/Thunderbolt and the rest of the industry will then follow its lead.

With at least 18-months until USB 4 ships, it is very possible we will see Thunderbolt/Lightning appear in many more products as manufacturers see that the forthcoming USB 4 standard will support them. Intel’s Thunderbolt 3 is after all supported by Mac, Linux and Windows.

What happens next?

Over 50 firms are now working to finalize the specification, which they hope will be ready for publication in mid-2019. Branding and marketing specifications will be announced subsequent to publication.

I build/develop products, what help is there for me?

Following publication of the final standard a series of USB Developer Days will be announced. You will be able to attend these for detailed technical training in USB4 and to learn all the latest news around for USB-C, USB Power Delivery, and “other exciting topics”.

Has Apple contributed to USB 4?

Apple is part of the USB Promoter Group. Additional members include HP, Intel, Microsoft, Renesas Electronics, ST Microelectronics and Texas Instruments.

When will USB 4 appear in products?

Don’t hold your breath. While it has been announced the specification hasn’t yet been formally published and the first systems implementing the as yet unratified standard won’t be available until 2020 at the earliest.

Hope this helps – please let me know if I’ve missed anything, or any Apple-related changes that may emerge as the standard heads to ratification.

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