Hi Nigel, I have hardcopy of a 15 or so page loose leaf manual for ?MDB PDP-11 LINE PRINTER CONTROLLER (CENTRONICS INTERFACE)?, and believe I also have the matching quad-height board in my stores. The manual has pinouts and a six or seven page ?theory of operation? section with timing diagrams and block diagrams, but no actual schematics. It claims toward the end that ?The MDB PDP-11 Line Printer Controller is completely compatible with DEC diagnostic software. Use that software to verify correct operation and for trouble analysis.? I would be happy to scan this later this evening and send you a copy if that would be helpful? ?FritzM.