>>>> "Greg" == Greg Ewing
<greg(a)cosc.canterbury.ac.nz> writes: 
 Greg> Sometimes I think it might be fun to build an emulator based on
 Greg> an FPGA. Then you wouldn't have any other instruction set in
 Greg> the way, either. :-)
 Greg> Has anyone out there done that?
I don't know about the PDP-11.  But yes, for the PDP-4 and PDP-8:
  
http://www.spies.com/~dgc/
      paul