9 Jan
2022
9 Jan
'22
4:57 p.m.
Probably. It's a 1973 version, the DD11-B is a MUD backplane, but it
seems to only have power plugs for +5,+15,-15. Looking at the MUD specs
I see there are backplane pins assigned for +20 and -5 so I might be
able to cobble something together.
That's one of the fun things about Unibus: There were so many different
types that there was no guarantee that anything would work in anything.
I know this one worked with an RX11 because that's what I used 30 years
ago. Would it work with an RX21? Maybe. Maybe not.
Note: I did check the DD11 and sure enough all of the DMA grant wires
are factory jumpered. I did remove the wire from one of them so I can
use either a RL11 or an RX21 but in the meantime I have a G7273 in there
along with the knucklebusters in the other slots)
Getting this MM11-DP to work might take a fair bit of thought. I'm
guessing that the DD11-F is significantly different from the DD11-B?
And the big question: What memories (if any) will work in a DD11-B
equipped pdp11/10?
C
On 1/9/2022 5:48 PM, Nigel Johnson Ham via cctalk wrote:
I would assume that your 11/10 has the suffix -NC.?
There were two
versions, the -NC used -15V four wire memory, and the later -SC used
+20V three-wire memory.
The +20V was provided by a MUD slot (Modified Unibus Device) and there
was usually a big red sticker in it warning to not plug a module in that
was not wired for it.
I believe it was standard in all models after the second version of the
11/05 -/10
I once tried to fix an 11/34 off-contract that somebody had done exactly
that to- I gave up when I found that the +20V had been routed to some
unobtainable ROMs on the CPU board.
cheers,
Nigel
Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
Amateur Radio, the origin of the open-source concept!
Skype:? TILBURY2591nw.johnson at ieee.org
On 2022-01-09 17:04, Chris Zach via cctalk wrote:
> I'm working on my pdp11/10 getting it back together. One problem I
> think I have is that the secondary memory (a Plessy 700101-100) may be
> shorting the -15 line for some reason. Working on it, but does anyone
> have a manual or anything like that for this kind of memory board?
>
> Alternately, what kind of Unibus 16k memory board exists to get a
> 11/10 from 16kw to 32kw of memory? Apparently I can't use a MM11-B as
> it requires +20 and -5, both of which are not provided by the power
> supply or sourced on a DD11-B backplane module. The 11/10 has +15,
> -15, and +5.
>
> On a related note, where did +20 come from for Unibus and which
> systems even supported it? Was it an 11/45,11/70 thing?
>
> Thoughts?
> C
>
> (Yes, I could build a regulator to take the 30 volts between +15 and
> -15 and create an independent 20 volts. Maybe. Likewise I could
> generate -5 from the -15 and a 7815 regulator. Maybe.)