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Thunderbolted: USB-C is our new connection overlord. Get used to it.

Glenn Fleishman | March 11, 2015
In with the new, and out with the...everything else.

USB 1.1 was always an intermediate step. At 12Mbps, it was far too slow. and USB 2 wasn't ready when Apple was. FireWire 400's introduction just a year later offered a vast improvement in speed. FireWire 800 doubled that a couple of years after, but despite a path to 1600 Mbps and 3200 Mbps, the standard was mostly single purpose: a way to move data rapidly among storage.

Enter Thunderbolt, the unifier. Originally slated to work over resilient fiber optic cables, allowing low power requirements and long distances, the first release was a bit of a compromise. It used copper wire and could extended only three meters (10 feet) maximum, but could also deliver power, which wasn't part of the optical specification. The first version shipped on a Mac just four short years ago.

The video standard DisplayPort, which has many potential variations of throughput, each of which can support a maximum refresh rate and monitor resolution, was supported as something that flowed over Thunderbolt, allowing forward compatibility. A Thunderbolt connection could support a DisplayPort-equipped monitor. Thunderbolt's first iteration was 10Gbps per channel, allowing an aggregate of 40Gbps (20Gbps in each direction). Thunderbolt 2 doubled that throughput.

But Thunderbolt stalled. While it's available in computers beyond Macs and in peripherals from many companies, it's never become pervasive. The rest of the industry has focused efforts on USB 3. Apple may eat a hunk of the profit in the PC market, but for unit volume among all connections, USB is orders of magnitude higher.

Apple didn't disregard progress on USB, adding USB 3 ports in Mac models that shipped in 2012. But you can only shrink a mini-DisplayPort connector used for Thunderbolt so far. It's got one correct orientation, and it can't easily be used to power other devices via a single port.

Thunderbolt was essentially too expensive to implement on inexpensive devices. It also has licensing rules that deterred some manufacturers. The USB-C adapter format avoids just these kinds of roadblocks.

The USB-C spec is under the control of the USB 3.0 Promoter Group, which doesn't include Apple among the key members that drafted version 3.1, but which engages in no preferential or discriminatory treatment about who may license or use it. Lightning can't support the data rate needed for peripherals, nor the wattage required for a notebook. Nor can it achieve the industry adoption needed for an ecosystem.

Within that worldview, USB-C seems more inevitable than unexpected, and we'll ultimately get used to it.

USB all that you can USB

While USB 3 is a few years old, USB-C only debuted last September, and was clearly designed in part to replicate the advantages of Apple's Lightning connectors. It's slim and reversible. Apple's flavor has a raw data rate of 5Gbps, and passes 29 watts of charge from the included power adapter.


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