Hi all, I did not think that my request for help would have so many people interested. First of all, I do have ONLY the 820-II motherboard without houses, or anything, and it does not have any FDC chip on its board. I got curious and found the document 610P72384_820-II_Technical_Reference_1984 available here http://www.textfiles.com/bitsavers/pdf/xerox/820-II/610P72384_820-II_Technic al_Reference_1984.pdf . On the schematics on page 60 and the following there is no trace of any FDC. On page 57 the manual says that the connector for floppy disk is a dual personality depending on the type of daughterboard installed in the motherboard ... but I not have ever seen it. From the movie http://www.youtube.com/watch?v=B9OwwolhLuE at minute 0:15 you can see a card that could be a controller. Does anyone know its exact code? On page 30 of the same document document 610P72384_820-II_Technical_Reference_1984 is specified the connection between the J1connector (37 pin D-type) and the controller SA 14030 (which i have with me but has huge dimensions in order to enter the houses of the xerox): names assigned to the wires connection seems that a protocol would been used but do not know what ... maybe SCSI?? In addition at pages 48 and 49, the same connector is used to connect the board with drive 5 "and 8" drives and here the names on the connecting wires are the same used with the classic drives. Thanks in advance for any useful info. Enrico