Get ready to rewrite your USB drivers. Again. Intel this morning released portions of an updated draft of the Extended Host Controller Interface 3, the latest version (0.9) of the part of the USB specification that handles register-level communications between the operating system and the USB host controller. The new spec could support transfer speeds of 4.8 Gbps, 10 times faster than the theoretical maximum of 480 Mbps of the current USB 2.0 specification. Finalization is expected in 2009.

Do we really need USB to go that fast? Few, if any, hard drives are capable of sustaining such transfer rates. So why does the world need such transfer rates from a serial bus? "We’re looking forward and preparing a USB 3.0 technology roadmap that will intercept emerging flash-based solid state drives (SSD) that will be able to transfer files this quickly, if not faster," according to Jeff Ravencraft, a technology strategist in the Communication Technology Lab at Intel in an Oct. 2007 blog post. Jeff leads Intel’s USB and Wireless USB projects.

To accommodate gigabit transfer rates at the physical layer, USB 3 uses packet routing technology and separate channels for data and acknowledgments. This replaces the polling and broadcast technique now in use. Also supported will be multiple data flows per channel, each with its own priority. At the application level, the spec will permit transfer speeds of around 300Mbps.

Also involved are in work on the spec are Hewlett-Packard, Microsoft, NEC, NXP Semiconductor and Texas Instruments. AMD and Dell also have reportedly expressed interest, which for AMD is an about-face from its prior opposition amid complaints of lack of accessibility to the specs.