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

===Open Host Controller Interface===
The OHCI standard for [[USB]] is similar to the OHCI standard for IEEE 1394, but supports USB 1.1 (full and low speeds) only; so as a result its register interface looks completely different. Compared with UHCI, it moves more intelligence into the controller, and thus is accordingly much more efficient; this was part of the motivation for defining it. If a computer provides non-x86 USB 1.1, or x86 USB 1.1 from a USB controller that is not made by Intel or VIA, it probably uses OHCI (e.g. OHCI is common on add-in PCI Cards based on an NEC chipset). It has many fewer intellectual property restrictions than UHCI.<ref name="LinuxUsbFaq">{{cite web|url=http://www.linux-usb.org/FAQ.html |title=Linux USB FAQ |author= |date=August 27, 2007 |accessdate=April 13, 2014}}</ref> It only supports 32-bit memory addressing,<ref name="ohci">{{Cite web |url=https://www.getusb.info/resources/hcir1_0a.pdf |title=Archived copy |access-date=2020-05-12 |archive-date=2020-05-18 |archive-url=https://web.archive.org/web/20200518185527/https://www.getusb.info/resources/hcir1_0a.pdf |url-status=dead }}</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}} OHCI interfaces to the rest of the computer only with [[memory-mapped I/O]].<ref name="ohci"/>