Intel releases USB 2.0 host interface spec.
Intel has published a single, unified spec. that will allow Microsoft, Apple, Red Hat, Sun and other OS makers to support USB 2.0 host controllers.
The specification, available on a royalty-free basis, essentially defines the way a host operating system talks to a computer's USB controller, and thus to any peripheral devices connected to it.
The new spec., called the Enhanced Host Controller Interface (EHCI), unifies the two alternative host controller interfaces developed with USB 1.0 and 1.1, which should simply OS' support for the connectivity standard. EHCI is compatible with USB 1.1 devices and hubs, even going so far as to work with existing device drivers.
That's done by supporting what Chipzilla calls USB 1.1 companion controllers, which leave the main USB 2.0 controller free to handle high-speed - ie. 400Mbps - bus traffic. That sounds suspiciously like a clever way of selling otherwise redundant USB 1.1 controller chips alongside the more up-to-date USB 2.0 versions.
And "the architecture is also highly optimised, and therefore consumes minimum CPU overhead - less than the amount that a USB 1.1 UHCI host controller consumes", Intel claims.
The next stage is to release compliance testing procedures, which will be released in the first half of next year, according to Intel. After that, it will publish the final version of EHCI. ®
The EHCI spec. and licensing Ts&Cs can be found on Intel's USBWeb site.