MM11-U/UP core memory backplanes

Eh, de nada - glad to help contibute to the knowledge base. With MM11-U gear, or MM11-L? I ask because, like I said, I still don't have 100% clarity on the MM11-L situation. I am pretty sure there are old MF11-L backplanes that can't be upgraded to parity this way (i.e. removing the jumper), and may not be upgradable to parity at all (i.e. it might take etch cuts that are 'impossible', if they are on the bottom side of the PCB). There's that jumper that should be there on non-parity units, but does not seem to be there on some older backplanes (so you can't remove it to make the backplane parity-capable); arguing that it's probably hard-wired in the etch on those older backplanes? And there seem to be a couple of pins that need to be bussed acros, for the MM11-L units to 'talk' to the parity controller. And if the parity jumper isn't there, logically those bussing etches might not be there either. So I have a little work ahead of me with an ohm-meter... Speaking of the jumper, and bussed signals: the parity board input pin that that jumper is connected to (when the parity board is not there) must be bussed to all three group locations in the MF11-L backplane, as a wired-OR of their proto-SSYN outputs. If it were daisy-chained among the three groups, you've have to put the board sets in in a specific order, no? (Otherwise a gap would lose the signal from the group(s) on the far side of the gap.) And there's nothing like that in the manual. Something else to check out on the prints and/or with a meter.. Anyway, please report back on your experiences, so if there's any useful info you pick up, we can learn from it. Noel