More details: I can't be sure because the Nova rack is presently in a crowded corner which is keeping me from removing the chassis from the rack in order to get its top panel off. But it appears to me that the mystery edge connector that I previously had the hard drive interface cable connected to is wire-wrapped over to slot 11, where the disk controller is plugged in.
Here are some pictures of the backplane: http://www.nf6x.net/2016/06/data-general-nova-3-backplane/ -- Mark J. Blair, NF6X <[email protected]> http://www.nf6x.net/
