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Switch to DD11B backplane?

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  by Bill Degnan - 06/27/2016 09:28
I was told that could abandon the DD11C and switch instead to a DD11B backplane

"...*RL11 *controller instead, which is a hex SPC compatible module. This means the A/B sections only have +5/GND power connections, and sections C/D/E/F are the standard UNIBUS SPC pinout. So the RL11 controller could go in any of the above backplanes in SPC slots 2 thru N-1 (ie, not first or last SPC slots, as those have UNIBUS IN/OUT in sections A/B). So your RL11 could go in a DD11-B slots 2 or 3, and a DL11-A/B/C/D/E/W could go in any of DD11-B slots 1 thru 4.
..."

But according to the RL01/RL02 manual one must install in a UNIBUS slot only after the jumper between CAl and CBl (NPR Grant) on the backplane has been removed, if the jumper exists. This jumper is present on all slots of the DD11B.

On my modified DD11C, slots 2 and 4 have this jumper removed, as far as I can tell. To test I put in a hex extender card, then found the pins where the NPR Grant could would be located. I used my volt meter to do a continuity test between the pins the NPR Grant card closes. If the connection beeps, I take this to mean that the backplane slot *is* jumpered and thus is not a candidate slot for the M7762 controller.

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