Anders Magnusson <ragge@ludd.luth.se> writes:
> Is there anyone that knows of programming specifications for the
> RP20 disks?

I believe you mean RH20 massbus controllers with RP06 or PR07 drives.
I haven't found anything, sorry.  You could try alt.sys.pdp10 or even
asking KLH directly.

Humorous:
  http://www.inwap.com/dp10/rh20.txt

Not for now, but the Ethernet interface will be intesting later:
  http://www.spies.com/~aek/pfd/dec/pdp10/EK-NIA20-RM.pdf