On Mon, 30 Jul 2007, Dave Higton wrote: > > That's not exactly the same as being compatible with a USB 1.1 host; > > the rest of it follows from the fact that the 2.0 spec is backward > > compatible with the 1.1 spec. > > But where is it documented that USB 2.0 is backward compatible with > USB 1.1? Does one have to read and compare every paragraph of the > two specifications?
You probably do. The specification doesn't state explicitly that it is backward compatible with USB 1.1. > USB 2.0 contains a statement that 2.0-compliant hosts must operate > correctly with 1.1-compliant devices, but that's a much weaker > statement than "USB 2.0 compliance requires USB 1.1 compliance" > (which is what I claimed, but was unable to back up) or "every > USB 2.0 device is required to be compatible with a USB 1.1 host". As far as I know, the differences between the way a USB 2.0 device and a USB 1.1 device are required to behave when connected to a USB 1.1 host reflect either errata in the 1.1 spec or new restrictions. But the 2.0 spec doesn't say this; in fact it hardly refers to the contents of the 1.1 spec at all. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
