I can't find my book on the M8256 (RX211) so I don't know if the switches are set right. I have a PDP-11/05 here that works fine and boots up RT11 or XXDP on an RX01 with an RX11. When I replace the RX01 system with an RX211 and an RX02 and try and boot RT11 the CPU hangs up at: 173546 , run light on. Requires a full reset to clear. I have tried other RX211s, RX02s, and cables and the same problem occurs. The disk is being accessed for a little while (4 or 5 "clicks") and dies.... If anyone here has a quick "config" fix I would appreciate it otherwise I guess I will dive into the boxes of manuals/fiche later today. Current 11/05 config: Main CPU M9312 w DY rom RX211 with RX02 8K core ODT and passes diagnostics. john PDP-8 and other rare mini computers http://www.pdp8.com