pdp 11/34 - a little help, please.

roberttx said:

... (though I'm not sure about the M7821 Interrupt Controller) from its previous life as a DAQ system.

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Your ordering & labeling is perfect. The fact that the SU-power is supplied "over the top" through a connector in Slot 3A indicates that these are all fairly early DD11-CK -- along with the use of pure wire-wrap in many cases. The M7821 in Slot 4 isn't significant. Early on DEC designed single-height "component level" modules that were used in C-D-E-F to assemble a number of different device controllers -- since they often share common subsystems (like interrupt control and addressing). Shortly thereafter they changed to quad-height device-controller-specific modules. However you'll still occasionally encounter "mix-n-match" situations with equipment-specific controllers, like yours.

roberttx said:

I'm not sure what to make of the huge void in the middle backplane. There's no grant cards, though they seem to be everywhere else they're needed, so I'm guessing that some cards were pulled prior to it being sold.

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In your case, probably yes ... but not necessarily. For reasons of economy sometimes folks hand-wired the chain from the underside and skipped the cost of the "knuckle-busters" -- so the modules might have been "wired out" during system life-cycle -- perhaps coincident to when the UNIBUS Repeater came into use? Flip the chassis over and check for a line of (probably) different colored hand-wrapped wiring in a daisy-chain configuration at some point. You never know ...

roberttx said:

I'm not sure how useful this part of the exercise was, but I feel better for having some drawings showing what's where, anyhow.

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Well, *I* found them useful, I appreciate you preparing them ... and I suspect that you'll find them to be useful too over the long-haul. Any idea what the M5864 and M6865 might be?

Also, while an M92 is presumably a predecessor to the M920, it's not simultaneously single- and double-height :->. Should be double-height in both positions there in the DB11-A.

Thanks for the kind words, guys.

pbirkel@gmail.com said:

The M7821 in Slot 4 isn't significant. Early on DEC designed single-height "component level" modules that were used in C-D-E-F to assemble a number of different device controllers -- since they often share common subsystems (like interrupt control and addressing). Shortly thereafter they changed to quad-height device-controller-specific modules. However you'll still occasionally encounter "mix-n-match" situations with equipment-specific controllers, like yours.

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I see. So the M7821, M1500, M1501 and W974 (which is just a ribbon cable connector) together form the functional equivalent of one quad height I/O card.

pbirkel@gmail.com said:

Any idea what the M5864 and M6865 might be?

Also, while an M92 is presumably a predecessor to the M920, it's not simultaneously single- and double-height :->. Should be double-height in both positions there in the DB11-A.

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Yep, that was a drafting error on my part. I've corrected the drawing to show both the M92 cards as double height. Apparently it's some kind of bus terminator? The M5864 and M6865 are described as Opto-isolated Input and Output cards, respectively.

Marty said:

Hi All;

Robert, Could You keep this in mind, I don't expect You to know what You will need, nor want at the present..
But, as long as the price isn't too high.. Would You be willing to sell ONE of Your DD11-CK ?? I need a pure Wire-wrap unit..
A DD11-DK would be OK as long as it is pure Wire-wrap and the price isn't too high..
Please keep this in mind, I don't need an answer at present, Until after You have decided what You need for Your working System and what You can get rid of that are spares..

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Yes, the plan is to sell off what I don't need for my system, though as you say, it may take some time to figure out what is surplus to requirements.

Along those lines, I do have a few questions that might help me with that.

1. How hot do these things get? The original racks had a couple of McLean blowers in them - would I need them for just one chassis?

2. Power requirements - I've seen some mention of this, either in the 11/34 manual or the BA23 manual, but the info I have is incomplete. I think that the CPU chassis has enough slots (9+4) to accommodate everything I want (and I could always add another 4 if needed) but will a single H765 provide enough current to drive it all? Any pointers here would be welcome.

3. However many chassis end up spare, I can't see me wanting to pack and ship a whole one! The key would be to break them down, but what level of granularity is optimal? At one end of the scale, it would be just splitting them in two and selling a card cage with backplanes as one lot and an H765 PSU as another. At the other, its selling an empty cage, several backplanes, a PSU box and several regulators, all individually. Where's the sweet spot?

4. The spare cards will, I think, have to go individually. It would seem wise to hold off on selling the second RS232 card until I have a working system to test it in, but what are the chances of it being feasible to test the funky I/O cards without dedicating an unreasonable amount of time to the project?

5. The power supplies. I've seen conflicting opinions, both here and in wider googling, about whether a load is essential for all of the testing, or just part of it. Does anybody have any strong views on this that they'd like to argue for?

That's all I can think of, for now, but I'm sure I'll be back with more questions as this project progresses.

Hi All;

Robert, "" 3. However many chassis end up spare, I can't see me wanting to pack and ship a whole one! The key would be to break them down, but what level of granularity is optimal? At one end of the scale, it would be just splitting them in two and selling a card cage with backplanes as one lot and an H765 PSU as another. At the other, its selling an empty cage, several backplanes, a PSU box and several regulators, all individually. ""

I could use a Backplane with a Card cage, I don't need a Power Supply, as I use modern Switchers.. But, just a Backplane would be fine as well..
My PDP 11/45 doesn't have anything, as far as card cages..
Thanks for Your Response..

THANK YOU Marty

roberttx said:

I see. So the M7821, M1500, M1501 and W974 (which is just a ribbon cable connector) together form the functional equivalent of one quad height I/O card.

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In the case of a DD11-CK, definitely. For example, originally the PC11 High-speed Reader/Punch controller was composed of M781 (basic PC11 Control) + M105 (Address Selector) + M7821 (Fast Interrupt Control), but later replaced by the quad-height M7810. However I suspect that the backplane labeled "Chassis1b" is *NOT* wired as a DD11-CK -- that is, with 4 standard SPC slots. The M7821 would be in row F in that case (not C) and a W974 in any of rows C-D-E-F indicates non-standard wiring. I doubt that particular backplane will work in any other configuration than its current configuration (which you have now documented ;->).

"Chassis2a" & "Chassis2b" are both also likely non-standard, as a M105 doesn't belong in a B row. Appears to be intended as a device selector spanning a set of 4 M1801. It would be interesting to see a schematic for that module. Without schematics you'll need to reverse engineer the modules from the parts-n-traces and experiment. Whether that's an "unreasonable amount of time" depends on your patience & priorities :->.

Anyway, I'd say that only "Chassis2c" (4 slot) " and "Chassis3c" (9 slot) are actually DD11 SPC backplanes. All of the other 4-slot backplanes are special-wired for that I/O interface, excepting "Chassis3d" which is specific to the modules in it & which together form the DB11 Unibus Repeater.

BTW, you can ship a whole chassis for ~$110-120 FedEx. Just pad it with foam-board and then a well-taped carton.

WRT blowers, the fans in the actual chassis should be fine so long as you have good ventilation around the cabinet and a "household" ambient temperature.

WRT power, it's reasonable to assume that the original configuration had a full module complement, so unless you load it back up again "to the brim" -- particularly with older power-hungry modules, you're probably fine.

I'd keep the spare serial I/O card on-hand as a spare.

Since you're probably less enamored with the lab-I/O modules than the CPU, you might use them as your "dummy loads" until you think that you have a good P.S. ;->. Only then start risking your prize possessions ...

roberttx said:

I think that the CPU chassis has enough slots (9+4) to accommodate everything I want (and I could always add another 4 if needed)

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I meant to point out more specifically that the 4-slot backplane in your CPU chassis is probably *not* what you want as it's custom -- unless you plan to reverse-engineer the lab-I/O modules. More likely what you want to do is to swap at least the 9-slot SPC-backplane ("chassis3c") there, plus optionally the 4-slot SPC-backplane ("chassis2c") -- which would then give you a standard 5 SU complement of SPC slots. You'll notice that both of those backplanes have their power supplied from below, as well as the DB11 backplane.

All of your specialty-backplanes have the power supplied from the top through slot 3A. One of those is what Marty is angling for -- perhaps "chassis2b" since we're not entirely sure how that is wired (most likely like "chassis2a", but who knows until you flip them all over and take some pictures from the underside :->).

Aha! So, at minimum, I need to remove "chassis1b" and replace it with "chassis2c". That should be enough slots for everything that I need, without having to use "chassis3c". Then, I suppose I'll have to follow the "over the top" power connector back and remove or otherwise make it safe.

And I guess I'll have to add pictures of the undersides to my to-do list.

roberttx said:

Aha! So, at minimum, I need to remove "chassis1b" and replace it with "chassis2c". That should be enough slots for everything that I need, without having to use "chassis3c". Then, I suppose I'll have to follow the "over the top" power connector back and remove or otherwise make it safe.

And I guess I'll have to add pictures of the undersides to my to-do list.

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Looking forward to that. As long as you need to move *some* backplane, I urge you to make it the 9-slot "chassis3c". You never know what the future will hold and someday you may wish to kick yourself for lack-of-foresight (and you decide to sell it to someone else, *they* may be doing the kicking :->). Most "interesting" peripherals are 6U modules -- and whereas the 9-slot choice gives you support for 7 more of those, the 4-slot gives you support for only 2 more. It's really no contest when making the choice when you have both in-hand.

WRT the power, I suspect that you'll find that the SPC-type backplanes used Faston (those spade-thingy) connectors and you'll want to remove the PCB-end and instead crimp on Faston connectors on those power wires -- possibly after extending them where necessary. Save the PCB end and keep it with the old-style backplane.

Been a bit tied up, but I'm back, briefly. I may not get an answer to this question in time, but I'll never get one if I don't ask it.

I have a chance at a half height rack that's perfect, except it's only 24" deep - so about 23" between front & back rails. DEC wants 25" between the rails for the BA11-K.

Think I'd get away with it? I'd be very grateful for prompt replies as there's not much time - I figure maybe 17 to 18 hours as of time of this posting, max.

Thanks!

roberttx said:

I have a chance at a half height rack that's perfect, except it's only 24" deep - so about 23" between front & back rails. DEC wants 25" between the rails for the BA11-K.

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Well, it will hang out the back a bit and you'll need to tie up your cables in a hanging-loop arrangement to allow you to pull the chassis forward to full extension (and rotate if you have those types of slides) but you can definitely finesse the slide mountings to fit. Your basic options are to invert the rear angle-bracket -- possibly needing to get/build a longer one -- or simply add a spacer-block between wherever you can reach with the rear angle-bracket and the rear rail. Sounds like you may need to do both. The block can be a nice chunk of aluminum (relatively easy to machine) or a scrap of hardwood. I've used hardwood as a gap-filler on several occasions and it works great, although I've always had a full 24" face-to-face between my front and rear rails. Plan on using more than two fasteners for each rear-rail attachment -- four never hurt anyone :->.

Thanks. That one didn't play out - somebody else wanted it more than I did. But an auction buddy said that he might have something suitable. I'll keep you posted.

It lives! Not the 11/34, yet, but this thread.

Yesterday, I found a rack for my pdp11/34. It cost me $5, plus $50 freight and a promised ass-kicking from the auctioneer, who didn't want to haul it (we have an arrangement where he'll haul stuff from remote sites to their warehouse that's closest to me, for me to pick up). It's identical to the rack that it came in when I got it, except it's single-wide and 3/4 height, which is more compatible with my space constraints.

AFAICT, they were both part of a custom run made for Sandia Labs, a spin-off from Los Alamos. That makes sense because Sandia maintains a blast-proof chamber at Pantex, where they periodically detonate the conventional explosive components of our nukes and measure the results. Back in the 1970s, my 11/34 was one of the DAQs for all of that.

So, my first task is going to be clearing some floor space to accommodate it. Next, I'll have to get my bench clear so that I can recap one of the power supplies, decide which of the expansion backplanes I'm going to transplant into the main chassis and start looking for an RL11 controller for the RL02 that I got the other month (it came with rails - yay!).

I have too many projects on the go right now. Aside from this one, there's the IBM 5110 that I need to address the disk drive and (when I can no longer avoid it) the printer, a PET 4016 with an 8050 floppy drive that some parts came for this week, an Epson Geneva that the cells for rebuilding the battery packs just arrived and two pdp11/73s that I need to build or buy cases for.

This might take a while...

roberttx said:

It lives! Not the 11/34, yet, but this thread.

Yesterday, I found a rack for my pdp11/34. ...

This might take a while...

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Isn't that the "fun" part? Glad to hear that you're making a little more progress towards the destination. The "mechanical stuff" is always more hassle than one expects. And getting the brackets/mountings "just so" is ... so much fun!

What do you have in the way of the 11/73 systems? I have an old Micro Vax II that I would love to downgrade to an 11/73 and need the control panel and CPU card.
Having the proper full depth rack will make life a lot better. You have all that stuff on a sturdy floor?

Qbus said:

What do you have in the way of the 11/73 systems? I have an old Micro Vax II that I would love to downgrade to an 11/73 and need the control panel and CPU card.

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I have two minimalist systems that came out of industrial controllers. No case, front panels or power supplies, so I need to make those. It's on the back burner right now, but the thread is here: http://www.vcfed.org/forum/showthread.php?54082-I-can-has-Qbus&highlight=

Qbus said:

Having the proper full depth rack will make life a lot better. You have all that stuff on a sturdy floor?

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It hasn't arrived, yet, but when it does it will be going in the part of my workshop that's a solid slab.