Intel and other companies have formed a group to promote USB 3.0, which should deliver more than ten times the speed of the existing USB 2.0 standard.

The third-generation Universal Serial Bus interconnect will transfer data at speeds up to 4.8Gbit/s, ten times faster than USB 2.0's 480MBit/s. It will be backwards-compatible with USB 2.0, which is backwards-compatible with the first USB 1.1 definition.

Intel stated that the USB 3.0 specification will be optimised for low power and improved protocol efficiency. The USB 3.0 ports and cabling will be designed with both copper and optical cable capabilities, meaning even higher speeds will be possible in the future.

The USB Implementers Forum (USB-IF), will act as the trade association for the USB 3.0 specification.

There is also a Wireless USB (WUSB) transfer format and this operates at 480Mbit/s, the same as USB 2.0, in its 1.0 incarnation. Intel also revealed a WUSB 1.1 interconnect format, operating at a speed of up to 1Gbit/s.

Jeff Ravencraft, Intel's technology strategist said: "The digital era requires high-speed performance and reliable connectivity to move the enormous amounts of digital content now present in everyday life. USB 3.0 will meet this challenge while maintaining (USB 2.0's) ease-of-use experience."

USB and FireWire

USB is a master-slave interconnect format, one requiring a host computer to manage the data transfers. The competing FireWire format, available in 400 and 800Mbit/s versions, and used predominantly in the Apple Mac and graphics world, is a peer-to-peer interconnect. Because it has a lower management overhead FireWire 400 delivers faster data transfers in real-world use than USB 2.0, with its theoretically faster maximum speed of 480Mbit/s.

FireWire 800 is faster still and uses Fibre Optic cables to exceed FireWire 400's maximum distance of 15 feet.

USB 3.0 should exceed FireWire 800's speed. There were plans originally for FireWire 1600 and 3200 formats, 2X and 4X faster than FireWire 400. However they have so far not been developed as FireWire 400 is good enough for all but the fastest disk drives. This limitation is revealed when FireWire is used to connect external disk drives. The external serial ATA (eSATA) standard may overcome this.

However, if USB 3.0 delivers on its speed promise then FireWire 1600 and 3200 may well remain still-born and eSATA come to naught.

The USB 3.0 Promotors Group consists of Intel, HP, Microsoft, NEC, NXP Semiconductors and Texas Instruments. The group says that USB 3.0 is needed for faster sync-and-go transfer applications in the PC, consumer and mobile data transfer markets. It is necessary because digital media is becoming ubiquitous and file sizes increasing up to and beyond 25 Gigabytes.

A completed USB 3.0 specification is expected by the first half of 2008. Initial USB 3.0 implementations will be in the form of discrete silicon.

USB is the most popular external device interconnect for PCs and laptops with 6.2 billion devices shipped since 2001.