I inserted two 32K core backplanes in the middle of my 11/40, but I have nothing in the core planes yet, except grant cards. In front is the CPU backplane which connects to the first core backplane with an M981. The 1st core backplane ise connected to the 2nd by a M920, and the last core backplane is connected to the general purpose backplane with another M920. Do I need grant cards in *all* empty core slots, or can I just put them in the slots that don't already have a M920? Is a core backplane only for core card sets? Can I put any old card in there? Once I get a stable system and it appears the 1st/CPU backplane is talking to the back (4th) backplane (serial card, etc) then I can start testing core in a systematic way, using the serial port. thanks in advance for any suggestions. b -- @ BillDeg: Web: vintagecomputer.net Twitter: @billdeg <https://twitter.com/billdeg> Youtube: @billdeg <https://www.youtube.com/user/billdeg> Unauthorized Bio <http://www.vintagecomputer.net/readme.cfm>