Cleaned up management of unused PSW bits

pubs/dec/pdp11/1110/README.md

@@ -1,10 +0,0 @@
----
-layout: page
-title: DEC PDP-11/10 Publications
-permalink: /pubs/dec/pdp11/1110/
----
-
-DEC PDP-11/10 Publications
----
-
-* PDP-11/10 Handbook (1969) [[PDF](http://research.microsoft.com/en-us/um/people/gbell/Digital/PDP%2011%20Handbook%201969.pdf)]

pubs/dec/pdp11/1120/README.md

@@ -7,4 +7,15 @@ permalink: /pubs/dec/pdp11/1120/
 DEC PDP-11/20 Publications
 ---
 
-* PDP-11/20 Handbook (1971) [[PDF](http://bitsavers.trailing-edge.com/pdf/dec/pdp11/handbooks/PDP1120_Handbook_1972.pdf)]
+- PDP-11/20 Handbook (1969) [[PDF](http://research.microsoft.com/en-us/um/people/gbell/Digital/PDP%2011%20Handbook%201969.pdf)]
+- PDP-11/20 Handbook (1971) [[PDF](http://bitsavers.trailing-edge.com/pdf/dec/pdp11/handbooks/PDP1120_Handbook_1972.pdf)]
+
+The above publications actually apply to several PDP-11 models:
+
+- PDP-11/10, which provided a minimum of 128 words of read/write memory (and 1024 words of read-only memory)
+- PDP-11/20, which provided a minimum of 4,096 words of read-write memory
+
+The 1971 Handbook also covers some additional models, which DEC says were "functionally identical":
+
+- PDP-11/15 OEM Computer
+- PDP-11R20 Rugged Computer

pubs/dec/pdp11/README.md

@@ -7,7 +7,9 @@ permalink: /pubs/dec/pdp11/
 DEC PDP-11 Publications
 ---
 
-* [PDP-11/10](1110/)
+* [PDP-11/20](1120/)
+	- PDP-11/20 Handbook (1969) [[PDF](http://research.microsoft.com/en-us/um/people/gbell/Digital/PDP%2011%20Handbook%201969.pdf)]
+	- PDP-11/20 Handbook (1971) [[PDF](http://bitsavers.trailing-edge.com/pdf/dec/pdp11/handbooks/PDP1120_Handbook_1972.pdf)]
 * [PDP-11/20](1120/)
 * [PDP-11/40](1140/)
 * [PDP-11/45](1145/)