The maximum throughput offered by USB is about to double with the news that the standard's industry Promoter Group has agreed the specification for the 10Gbps USB 3.1.

USB 1.0 first appeared in 1996 with up to 12Mbps throughput, while the still ubiquitous USB 2.0 succeeded it in 2000, boosting speeds to 480Mbps. SuperSpeed USB 3.0 arrived in 2008, offering maximum theoretical throughputs of 5Gbps.

The actual appearance of each iteration in products bought by customers lagged by two to three years, a timeline that is likely to be shortened only slightly by USB 3.1 SuperSpeed+ (note the + added to the name).

"The USB 3.1 specification primarily extends existing USB 3.0 protocol and hub operation for speed scaling along with defining the next higher physical layer speed as 10 Gbps," said USB 3.0 Promoter Group Chairman, Brad Saunders.

"The specification team worked hard to make sure that the changes made to support higher speeds were limited and remained consistent with existing USB 3.0 architecture to ease product development."

The spec will be pushed to developers through a series of conferences to be held in the US this month, Europe in October and Asia in December.

Meanwhile Intel's Thunderbolt interface is still in the offing despite the fact that most equipment vendors with the notable exception of Apple have ignored it. Already at 10Gbps, version 2 is set to reach 20Mbps.

Thunderbolt is more expensive of course (even the peripheral cabling is expensive) but its proprietary underpinnings probably don't help endear it in some quarters either. Intel seems content to promote it as a wider-ranging, high-end interface.

USB 3.x's Promoter Group also includes Intel as well but also HP, Microsoft, TI, ST-Ericsson and Renesas Electronics. Expect mainstream adoption by late 2014 at the earliest.