USB on SGI systems
Very very limited support on Tezro, Fuel, Origin 3(x)00 systems.
In IRIX the file invent.h recognizes only four USB device classes, the root hub/controller, USB hubs, human interface devices, and the graphics compositor (used to composite multiple VPros into a single output), while the at-large USB specification includes a significantly larger list of device classes. To further muddy the water, invent.h also includes a note that mentions the listed classes might not match those defined in the at-large USB specification.
See http://forums.nekochan.net/viewtopic.php?f=3&t=16730783 for more detailed information on how to set up USB keyboard and mouse.