Editing Host controller interface (USB, Firewire) (section)

===Universal Host Controller Interface{{Anchor|UHCI}}===
'''Universal Host Controller Interface''' ('''UHCI''') is a [[proprietary hardware|proprietary]] interface created by Intel for [[Universal Serial Bus|USB]] 1.x (full and low speeds). It requires a license from Intel. A USB controller using UHCI does little in hardware and requires a software UHCI driver to do much of the work of managing the USB bus.<ref name="LinuxUsbFaq"/> It only supports 32-bit memory addressing,<ref name="uhci">{{cite web|url=http://ftp.netbsd.org/pub/NetBSD/misc/blymn/uhci11d.pdf |title=UHCI11D.DOC |website=Ftp.netbsd.org |accessdate=2017-01-10 }}</ref> so it requires an IOMMU or a computationally expensive bounce buffer to work with a 64-bit operating system.{{citation needed|date=March 2019}} UHCI is configured with port-mapped I/O and memory-mapped I/O, and also requires memory-mapped I/O for status updates and for data buffers needed to hold data that needs to be sent or data that was received.<ref name="uhci"/>