On Mon, Mar 16, 2015 at 3:55 PM, Johnny Billquist <bqt at softjar.se> wrote: Nitpick: The 11/40 "class" machines did not have split I/D space. Split I/D space was the 11/45,11/50,11/55 and 11/70, before we move into "modern" PDP-11s.. That's what I said - "shared I/D" as opposed to "split I/D"