General Question about UNIBUS backplanes

[Mattis Lind]

2016-05-23 15:38 GMT+02:00 william degnan <billdegnan at gmail.com>:

> >
> >
> >
> >     > So I decided to insert two 32K core memory backplanes
> >
> > 32KW, those would be MM11-U backplanes, right?
> >
>
> Here is a closeup.  I have have related docs.
>
> http://vintagecomputer.net/digital/pdp11-40/32Kx16-MemoryBackplane_5010344C_label.jpg
>
>
> >
> >     > My plan is to replace the solid-state RAM card with core, and this
> > will
> >     > free up a slot on the 4-slot backplane for a terminator.
> >
> > Terminators all only go in the last slot of the last backplane anyway
> > (either
> > that, or a UNIBUS 'out' cable), so adding extra backplanes shouldn't give
> > you
> > "a slot .. for a terminator".
> >
> >
> Thanks for clarifying.
>
>
> > Also, Paul's point is a good one: the hex memory cards need so-called
> 'MUD
> > slots' (hex), not SPC slots (quad), and only (IIRC) the DD11-C/D have MUD
> > slots. (Those came in with the 11/04-34, IIRC).
> >
> >
> It is 3011-cf  / 70-12445  1979
>
>
> >     > the serial card seems to have stopped working. It appears that the
> >     > console program is being loaded and runs from the M9312 but nothing
> > is
> >     > appearing on the terminal. I cannot send an "A" to the terminal,
> the
> >     > most basic test I can think of.
> >
> > Hmm. You can read/write the console registers from the console, though,
> it
> > sounds like? My guess would be that if your serial port is EIA, somehow
> > you're missing -15V or something on the DD11 in its new location. Study
> the
> > -11/35-40 system manual to learn about which 'bricks' supply which
> voltages
> > to which system units.
> >
> >
> OK, but will always watch this.
>
>
> > And while you're at it, check that you have the right 'bricks' for the
> > MM11-U.
> > The -11/35-40 system manual has lots of text on how to support the
> MM11-U.
> >
> >     > Can you only use the core backplanes for core memory (assume yes),
> or
> >     > are they capable of holding other types of cards temporarily?
> >
> >
>
>
> > AFAICR, the MM11-U backplane does _not_ have an SPC slot in it. IIRC, the
> > 16KW MM11-U board set is a quad controller board, and 3 hex boards (core,
> > X-Y
> > and something else). So two sets (the backplane holds two) would be 8, so
> > one
> > empty slot - which IIRC is blank. Check the MM11-U manual, it's
> available.
> >
> >
>
> Came with M7891 RAM installed in the 3011-cf backplane.
>
>
> >     > I have one slot that needs the npg, it's in place.
> >
> > ??? _Every_ SPC/MUD slot which does not have a DMA device in it _must_
> have
> > the jumper on the backplane (or the _double_ width UNIBUS grant card,
> whose
> > number escapes my memory, which contains a NPG jumper). Not sure if that
> > was the import of what you wrote there.
> >
> >
>
> Note - System came to me as thus, after the CPU, the 3011-cf backplane had
> the following:
>

I have no idea what "3011-cf" is. Isn't it just a a DD11-C backplane with
power-wring entering from the back, rather than through small circuit
boards?


>
> UNIBUS 10 A-B (LEFT SIDE OF UNIBUS)
> M7856 10 F-C (RS232 WITH 19.2 OPTION?)
> G7273 11 C-D
> 7891 12 A-F (64k MEMORY)
> M9312 13 A-B (ROM CARD)
> 672A 13 D (GRANT CONT.)
>

That looks like a reasonable setup provided that jumpers W1- W5 are
installed on the M9312. You should be able to install the RL11 in slot 11
when you remove the G7273. Make sure that the wire-wrap between CA1-CB1 is
cut on slot 11 if you install the RL11 there. Also make sure that CA1-CB1
wire-wrap jumper is installed in slot 13 (or install G7273 card in 13C-D)

>
> I am going to switch to another backplane and start over.  Don't know what
> I am doing yet to be honest.  I have to read the manuals and get better
> educated to properly get these parts working together correctly.
>

But all this still doesn't now explain the problem that you cannot access
(or send characters to)  the serial port. It could very well be the power
problem as Noel suggested. If I were you I would try to get back to the
state where it worked, shortening the Unibus to just include the 4-slot
back plane and the CPU backplane and also remove the RL11 for now. Then
install the RL11 in slot 11 when everything is working.

/Mattis



>
> Bill
>
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