BIOS EHCI Hand-Off
Possible values of an option:
The option description:
The given option is responsible for the mechanism of transmission of control of interface ECHI of controler USB 2.0 from the device to the device. At USB-periphery usage it is important to eliminate a situation when two and more USB devices (more precisely, the driver of these devices) simultaneously suppose that have exclusive access to the ECHI-interface: the similar situation can lead to operating system crash. Support of the given mechanism appeared only in Windows XP with the second service pack, earlier versions (including Windows XP SP1) are deprived possibility correctly to process this situation and support of the mechanism of transmission of control by interface ECHI should be laid on BIOS.
Thus, if you it is installed Windows XP SP1 (or earlier versions of an operating system), for an option have to have an indicated value [Enabled]. Presence Windows XP SP2 (and later service packs), Windows Vista allows to transfer control to an operating system (selecting [Disabled]).
Interfaces OHCI (Open Host Controller Interface) and EHCI (Enhanced Host Controller Interface) describe, as a matter of fact, hardware implementation of controler USB. To the specification 1.1 USB-controlers there corresponds interface OHCI, controlers of the specification 2.0 are under construction on the basis of EHCI.