Plessy core memory

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.)