ITS configuration has the Rubin 10-11 in the 3,,0-3,,777777 range.
The documentation says it's one moby lower.
Two more PDP-11s were attached at some point.
This restores the text from the GPL release. Our existing file had 2048
bytes duplicated around the description of PGWRIT, and 2048 bytes
missing around the definition of VIDSW.
(The other files we have from the GPL release are all intact.)