The PDP-10 KL10 at the RCS/RI was used to control a real-time flight simulator at Sikorski. It had one of the RH20 Massbus controllers connected to a DTR01 cabinet holding a DR01 chassis. The DR01 was, I think, connected to a DR11 chassis that had A/D and D/A converters boards inside. You could use the same DTR01 subsystem to connect two PDP-10s together with Massbus, or connect a PDP-10 to a PDP-11 with Massbus. -- Michael Thompson