Thanks to Tim, Jerome and Tony D. so far. I have more info after dragging the little puter out of it's rack. The backplane is third-party, not DEC, and has integral termination (no terminator card per se.) It has 8 quad-height slots. 1A-B M8192YB 1C-D MTI MXV22 (RX11 clone) 2A-B MTI MLV11M HD cont. 2C-D ?? 306 BootRoms etc. 3A-B M8043 quad SLU (console) 3C-D blank 4A-B Camintonn MLV11-J 4x SLU 4C-D blank 5A-B blank 5C-D blank (was Pertec VRG-Q) 6A-B Camintonn 256KW MOS [4164] 6C-D blank 7A-B blank 7C-D blank 8A-B blank 8C-D blank The HD is a Rodime and boots RT11SJ Ver 5.02 The RX02 is a single Mitsubishi 1/2 height 8". The system boots and runs as it is above. LP and LQ are on the second (3rd party) SLU, and the RT11 complains on boot if it's taken out. SHOW DEV shows TT; LD; DL; DY; LP; LQ; NL: VM; and XL. Question: Is the RLV11 appropriate and if so, which slots do they go in? Thanks again for everyone's help Cheerz John