bqt at update.uu.se
Sun Sep 6 07:14:46 CDT 2015
On 2015-09-05 20:25, Noel Chiappa wrote:
> > From william degnan
> > I was looking to see if references to the tm11 were "module/card" or
> > backplane interface.
> I think pretty much all that earliest generation of UNIBUS interfaces were
> stand-alone backplanes (i.e. 19" wide things that went in an H960 in a fixed
> location, and were filled with the small Flip Chip modules); the RK11-C,
> RP11-C, RF11, and TC11 all are.
Partly correct. All early Unibus controllers which did DMA had their own
backplanes. Which is why the NPR is obnoxious on the Unibus. Unlike the
BR lines, the NPR is normally always just jumpered in the backplane, and
located away from the BR lines. When DMA on single cards became more
common, this became an obvious issue on the Unibus. You have to cut the
wire on the backplane, and when you remove the card you either have to
reinsert the write, or get the bug grant card that is double height,
which also do the NPR jumper.
But non-DMA controllers were single cards even back in the early days of
the Unibus, like the DL-11.
(Early DMA controllers were all multiple cards, so having their own
dedicated backplanes were a pretty sane idea.)
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