No processor is needed. Cycles are freed up for other tasks at both ends. When a write function is executed on the PCI bus, the adapter technology converts that PCI function into a VME write function on the VME bus. It is as if the write had been to a local PCI resource. By working at the bus level, the adapters constitute a very simple solution from a software standpoint.
System software is basically unaffected by the virtual dual-nature bus.
Programmers are spared having to deal with the complexities of network topologies. A contiguous block of memory on a VME bus, when mapped to the PCI bus, is distributed across noncontiguous blocks of 4 Kbyte each. This is very important where virtual memory resources that are not contiguous are allocated by an OS in physical memory. By maintaining the VME side of the application, the combination system is afforded all of the proven advantages of the bus that has supported industrial applications for well over a decade. The firmly entrenched hundreds of vendors offering supporting products are testimony to the success of the bus.