VTSERVER booting

Unibus and Qbus are actually quite similar, to the extent that devices for either bus generally look the same to the software (the DL11 and DLV11 serial ports have the same registers, same bit allocations, ditto for the RK11 and RKV11 etc...). The logical ideas behind the bus -- the types of bus cycle, the signals used, etc are also pretty similar. The only issue comes if you get into 22 bit addressing, Qbus devices that do DMA have 22 bit address registers, Unibus ones have 18 bit address registers and the address goes via the Unibus Map to turn it into a 22 bit address. DEC sold a Unibus -> Qbus adapter (it requires that the CPU, or more specifically the arbiter is on the Unibus side), the DW11-B that seems to work well (I have had mo problems hanging any Q-bus device off my 11/45 using it). I believe there were 3rd party boards that went the other way. -tony