Figure 13-1 : Relationship of VME Bus to System Bus On the Silicon Graphics system bus, the VME bus controller acts as an I/O device. On the VME bus, the bus controller acts as a VME bus master.
The VME controller has several tasks. Its most important task is mapping; that is, translating some range of physical addresses in the Silicon Graphics system address space to a range of VME bus addresses. The VME controller performs a variety of other duties for different kinds of VME access.