Difference between revisions of "H9273 backplane"

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It was a [[QBUS#Variable_address_size|Q18]] backplane, but it is relatively easy to [[upgrading QBUS backplanes|upgrade it to Q22]].
 
It was a [[QBUS#Variable_address_size|Q18]] backplane, but it is relatively easy to [[upgrading QBUS backplanes|upgrade it to Q22]].
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The manual says the BA11-N was for [[PDP-11/03L]]'s, but the [[LSI-11]] used in that machine was only Q16 capable, making the Q18 backplane superfluous, like that in the [[BA11-M mounting box]]. Once the [[PDP-11/23]] appeared, BA11-N's could be used with it (and perhaps the BA11-N was looking forward to this machine) - but after the -A revision of the /23's [[KDF11-A CPU]] (Q18 only), later revisions really were better off with a Q22 backplane, as in the uprated [[BA11-S mounting box]].
 
  
 
Since it was a Q/[[CD interconnect|CD]] backplane, dual-width [[QBUS]] cards could only be placed in the left-hand slots, and quad QBUS-only cards had to not use any pins on the [[DEC edge connector contact identification|right-hand C/D connectors]]. (The only DEC card with a problem with this seems to have been the [[MMV11-A QBUS core memory|MMV11-A]].)
 
Since it was a Q/[[CD interconnect|CD]] backplane, dual-width [[QBUS]] cards could only be placed in the left-hand slots, and quad QBUS-only cards had to not use any pins on the [[DEC edge connector contact identification|right-hand C/D connectors]]. (The only DEC card with a problem with this seems to have been the [[MMV11-A QBUS core memory|MMV11-A]].)
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* [http://www.bitsavers.org/pdf/dec/qbus/MP00740_1123_schem_Oct81.pdf PDP11/23 Field Maintenance Print Set] (MP00740) - The H9273 is covered in the BA11-N Field Maintenance Print Set (MP00487) on pp. 41-51
 
* [http://www.bitsavers.org/pdf/dec/qbus/MP00740_1123_schem_Oct81.pdf PDP11/23 Field Maintenance Print Set] (MP00740) - The H9273 is covered in the BA11-N Field Maintenance Print Set (MP00487) on pp. 41-51
  
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[[Category: DEC Hardware]]
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[[Category: QBUS Backplanes]]

Latest revision as of 12:51, 6 December 2022

The H9273 backplane is a 9-slot Q/CD QBUS backplane, the standard backplane in the BA11-N mounting box. It could hold quad-sized cards.

It was a Q18 backplane, but it is relatively easy to upgrade it to Q22.

Since it was a Q/CD backplane, dual-width QBUS cards could only be placed in the left-hand slots, and quad QBUS-only cards had to not use any pins on the right-hand C/D connectors. (The only DEC card with a problem with this seems to have been the MMV11-A.)

External links

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