General Question about UNIBUS backplanes

[Mattis Lind]

2016-05-23 1:07 GMT+02:00 william degnan <billdegnan at gmail.com>:

> Paul,
> What terminator card exactly?  As I had written originally, the system was
> functional before I added the core planes.  I was thinking that I needed a
> terminator now that I have more than just the cpu plus four slot plane, but
> I did not have the space for it along with all of the cards I already have
> installed.
>
>
> http://vintagecomputer.net/digital/pdp11-40/card-layout_moved-plane_Pic2.JPG
> (I removed the grant cards from the core planes per Tony's suggestion.)



You don't have a terminator in the last slot of the bus. There should be a
M930/M9301/M9312 installed there, not a RL11. It is possible to put the
M9312 / M9301 there if you install the five jumpers (In my 11/10 there is a
M9301-YF installed in a regular Unibus slot). With jumpers in the
M9301/M9312 will terminate the BGx and NPG signals as well. Without jumpers
these signals will be unterminated which is not good.

Be careful to not put it into a MUD slot with the jumpers in, though.

It is not clear to me if the DL11-W repsonds correctly when you try to
address it or just doesn't output anything.

Check grant continuity from last slot to the M981. But just to output a
character on the console BG/NPG continuity wouldn't matter. Booting from
the RL11 will not work unless the NPG chain (and BG chains are OK).

I actually think that the reason for the RL11 not working is that the grant
signals don't have a pull up anywhere in your config.

/Mattis



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