On Sun, Feb 28, 2016 at 12:37 PM, Noel Chiappa <[email protected]> wrote:
> > From: Bill Degnan > > > Very useful, thanks. > > Eh, de nada - glad to help contibute to the knowledge base. > > > I will try this. > > 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 > My thought is that with my PDP 11/05 with S chassis / BA11-K. I am thinking I could apply this knowledge to my situation, even if it's not the exact match. I have the same memory and controller cards H217C and H217D (parity / non parity) to play with in the same chassis, if I can locate what jumper to change. 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>
