Four papers by Gordon Bell nicely cover the PDP-11 from inception to retrospective (available from Gordon's website):
- G. Bell et al., proceedings of the
AFIPS Joint Computer Conferences Spring 1970:
"A new architecture for mini-computers: the DEC PDP-11" - G. Bell and W.D. Strecker, proceedings of the
3rd annual symposium on Computer architecture 1976:
"Computer structures: What have we learned from the PDP-11?" - G. Bell, in Perspectives on Computer Science: From the 10th Anniversary
Symposium of the Computer Science Department, Carnegie-Mellon University
(1977):
"What have we learned from the PDP-11?" - G. Bell and W.D. Strecker, in
25 years of the international symposia on Computer architecture (1998):
"Retrospective: what have we learned from the PDP-11 - what we have learned from VAX and Alpha"
As background for the PDP-11/74 is very interesting to look into