People often ask for the jumper settings or system configuration requirements for a particular PDP-11 board. Given the thousands of such boards available (from DEC as well as third-party vendors), it's impractical to include such information in this FAQ. However, Tim Shoppa has collected quite a bit, and made it available off of a link from his http://metalab.unc.edu/pub/academic/computer-science/history/pdp-11/ page. There are also many DEC Micronotes archived there.
Regarding the Micronotes: The one claiming to explain the differences between the 11/70, 11/83, and 11/93 actually discusses the differences in the cache design between the 11/83 and 11/93.
Will Kranz is also making various hardware-specific information available at http://www.conknet.com/~w_kranz/pdp11/pdp11.htm.