Sun4d is a computer architecture introduced by
Sun Microsystems in 1992. It is a development of the earlier Sun-4 architecture, using the XDBus system bus,
SuperSPARC processors, and SBus I/O cards. The XDBus
was the result of a collaboration between Sun
and Xerox; its name comes from an earlier Xerox
project, the Xerox Dragon. These were Sun's largest machines to date, and
their first attempt at making a mainframe-class server.