[Info-vax] RB730 Integrated Disk Controller (R80/RL02) usable with VAX-11/750?

[Bob Koehler]

In article <ipqpfi$qvl$1 at Iltempo.Update.UU.SE>, Johnny Billquist <bqt at softjar.se> writes:
> 
> Except then of course it isn't the system bus, but just an I/O bus... :-)

   If everything except the CPU-memory connection is on the same
   bus, and CPU and memory are also on that bus, then which is the
   system bus?

> 
> I'm not even sure I understand that comment.
> The Unibus map is a way to map the Unibus 18-bit address into a 22-bit 
> address (for large PDP-11s) or 32-bit address (for VAXen).

   It's a matter of how big the "map" is.  Drivers had to break up
   large transfers, so I assume the "map" was only one entry (more
   like an APR than a map).  Or maybe it was just a few, I forget
   the upper limit, but I recall it was only for the 11/725.