See if you can find the cpu manuals for an 11/70.
There are some
documentation on the KM11 in those, I seem to remember.
The original KM11 (I was given a pair _after_ making my homebrew
version..) consists of 2 boards -- IIRC W130 and W131. One contains the
switches and lamps, the other the driver transistors, etc. The latter
goes into the backplane slot and had an edge connector on the end to
connec to the former.
I think I got the schematics in the RK11-C printset, certainly it's
either there or in the 11/45 prints.
-tony