Help with UNIBUS information

[RetroNewbie]

After getting my QBUS PDP-11 assembled from boards up and running, I decided to slowly get all the bargains that I can on UNIBUS cards to hopefully (one day) replicate what I did with QBUS, even if I know it'll be much harder. I still have to learn a lot about UNIBUS and I wanted to know your opinion about what big differences should I be in the lookout for between the two buses.
Some of my questions are:

• is board compatibility as straight forward as in qbus systems?
• is wire-wrapping the backplane needed for a working system and it is always configuration dependant?

The boards

This is the only really interesting board, it's an M8727-CX. It should have 256KB of memory, and I have some questions about it:

• does it need a controller board to get interfaced with a system?
• Does anyone have a part number or a datasheet for this RAM ic?

This should be one board out of two that is part of a controller for SDI disk driver.

• How hard would it be to get the other board?
• Is it even worth it and usable?

I also got two RA81 SERVO CONTROL board that I was planning on using to scavange parts, unless anyone needs them for replacement parts or anything else.

'

Thank you in advance for the help!

 

[saipan59]

The disk controller board you have is half of a UDA50:

UDA50 Disk Controller - Computer History Wiki

gunkies.org

A UDA50 is probably "essential" in a Unibus system IF you will have SDI drives.

Pete

 

[MattisLind]

Not sure if it is a typo or not, but the memory board looks like a M8728, 256k memory array for 11/70 and VAX-11/750. The chips are 16 k DRAM chips. It will require a memory controller. The VAX 11/750 used the L0011 board for the 256 k arrays.

 

[gslick]

If you wanted to build up a UNIBUS PDP-11 from bits and pieces, one of the easier ways might be to put together an 11/84 system from pieces. It would still end up being expensive by the time it was functional.

Special parts are the backplane and the M8191 KTJ11-B UNIBUS adapter, then you need to add an M8190 KDJ11-B and one or two M8637 MSV11-J memory boards, which are the same as the Q-BUS versions. Putting an appropriate power supply together could take a bit of work too.

For example currently on eBay:

DEC DIGITAL 54-18045-01 PDP 11/84 9 SLOT BACKPLANE
https://www.ebay.com/itm/225862763873

DEC Digital Equipment Corporation M8191 PDP-11/84 UNIBUS ADAPT KDJ11B (B15)
https://www.ebay.com/itm/225955348847

 

[saipan59]

[EDIT: 11/24, not 11/04]
Isn't an 11/24 the simplest Unibus PDP? One hex module for CPU, another for memory.
As I recall, the BP is a bit unique, but perhaps can be made from a DD11-DK or similar??

Pete

 

[MattisLind]

11/04 is the simplest being just one board. As far as I understand an 11/24 need a unibus map board as well. The M7133 and M7134 and a special backplane.

 

[pbirkel@gmail.com]

11/04 is the simplest being just one board. As far as I understand an 11/24 need a unibus map board as well. The M7133 and M7134 and a special backplane.

And with the M7263 (KD11-D 11/04 processor) you can use a generic DD11 backplane ...

 

[RetroNewbie]

Not sure if it is a typo or not, but the memory board looks like a M8728, 256k memory array for 11/70 and VAX-11/750. The chips are 16 k DRAM chips. It will require a memory controller. The VAX 11/750 used the L0011 board for the 256 k arrays.

Yes it was a typo. Thank you for the info, does it require a special backplane too if you know?

 

[RetroNewbie]

Thank you everyone for the suggestions, I guess I'll have to decide a model and stick with that one. The 11/04 seems the most promising so far.

 

[pbirkel@gmail.com]

Yes it was a typo. Thank you for the info, does it require a special backplane too if you know?

For the 11/70 it requires a whole special "box" (which isn't Unibus); see the MK11.
For the 11/750 it requires a whole special computer; the L0011 controller isn't a Unibus module.

 

[RetroNewbie]

For the 11/70 it requires a whole special "box" (which isn't Unibus); see the MK11.
For the 11/750 it requires a whole special computer; the L0011 controller isn't a Unibus module.

Both seems like expensive options...

 

[pbirkel@gmail.com]

Both seems like expensive options...

Indeed! The lesson here is that not all hex-height modules are designed for direct use on the Unibus with PDP-11 processors. One needs to research the specific module to determine where it can be used, and how. Just seeing six tabs isn't nearly specific enough; that mechanical design was used by DEC in many modules serving a wide variety of purposes.

 

[RetroNewbie]

Indeed! The lesson here is that not all hex-height modules are designed for direct use on the Unibus with PDP-11 processors. One needs to research the specific module to determine where it can be used, and how. Just seeing six tabs isn't nearly specific enough; that mechanical design was used by DEC in many modules serving a wide variety of purposes.

I guess I learned the hard way

 

[qcook]

11/04 is the simplest being just one board. As far as I understand an 11/24 need a unibus map board as well. The M7133 and M7134 and a special backplane.

The 11/24 backplane is now (and has been for some time, mislabelled as a DD11-DK) available on ebay. The 11/24 should also be more capable than an 11/04 — memory management, EIS, floating point, etc. Memory map is only required when using greater than 256 KB of memory.

VINTAGE DEC DD11-DK 9 SLOT UNIBUS EXPANSION BACKPLANE, 70-16905-00 | eBay

Find many great new & used options and get the best deals for VINTAGE DEC DD11-DK 9 SLOT UNIBUS EXPANSION BACKPLANE, 70-16905-00 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[gslick]

For example currently on eBay:

DEC DIGITAL 54-18045-01 PDP 11/84 9 SLOT BACKPLANE
https://www.ebay.com/itm/225862763873

View attachment 1276178

At first glance I thought that 9-slot PDP-11/84 backplane was the same one that I have in my PDP-11/84-E, but it is slightly different and I cannot find any documentation that exactly matches that one.

The 9-slot backplane that I have in my PDP-11/84-E must be an H9277-B 54-17228-01 version. It matches the figure below in a PDP-11/94 manual. One difference is that that eBay PDP-11/84-AC backplane only has 4 cable connectors next to the CPU and memory slots while the PDP-11/84-E backplane has 5 connectors. J4 is not a cable connector, it has pins for NPG jumpers for slots 5 through 9. J5 and J6 connect to the M8190 CPU board, J2 connects to the front panel, J3 connects somehow to the power supply, and J1 connects to the console panel. I don't know how that eBay PDP-11/84-AC backplane would connect to the console panel.

Does anyone have a scan of this manual: EK-1184E-MG PDP-11/84-E User's and Maintenance Guide
Back in 2015 "tradde" said they had a hard copy of EK-1184E-MG-002. It would be nice to find a scan of that.

https://forum.vcfed.org/index.php?t...s-and-card-interoperability.46921/post-567332


http://www.bitsavers.org/pdf/dec/pdp11/1194/EK-PDP94-MG-001_Sep90.pdf

 

[pbirkel@gmail.com]

The diagram seems to imply that the MLM is optional; I didn't think that was ever the case with the 11/84? Perhaps there's a missing footnote to the effect that slots 5-8 should first be populated and then "if you must" an SPC can be used instead of the MLM.

 

[gslick]

The diagram seems to imply that the MLM is optional; I didn't think that was ever the case with the 11/84? Perhaps there's a missing footnote to the effect that slots 5-8 should first be populated and then "if you must" an SPC can be used instead of the MLM.

The main reason why I shared that particular Figure 8-19 from the EK-PDP94-MG-001 PDP-11/94-E System User and Maintenance Guide is that it shows the H9277-B 54-17228-01 9-slot backplane with the 5 ribbon cable connectors J1, J2, J3, J5, J6 to contrast it with the 9-slot backplane photos in that eBay listing, which only has 4 ribbon cable connectors, and doesn't appear to have the NPG jumpers in the position where J4 is. That figure also shows that the J5 and J6 backplane connectors connect to the M8190 KDJ11-B, which is being replaced by the M8981 KDJ11-E in the upgrade, which is useful information when trying to figure out how everything is wired up.

That Figure 8-19 isn't the reference on the minimum load module rules. The EK-PDP94-MG-001 PDP-11/94-E manual has a section 4.2.1 Backplane Configuration Rules, which mentions the M9713 minimum load module requirements.

If the PDP-11/84-E MLM rules are the same, or any different, I assume they would be detailed in the EK-1184E-MG-002 PDP-11/84-E User's and Maintenance Guide, which unfortunately no one has shared a scan of that anywhere that I have found yet.

 

[pbirkel@gmail.com]

That Figure 8-19 isn't the reference on the minimum load module rules.

I agree. However once they went to the trouble of pointing out the optionality IMO they should have been more specific by establishing conditionality (just a simple asterisk and "it depends" footnote would have been fine) rather than being inconsistent within their technical documentation. A lesson here is that one needs to grok *all* relevant documentation before one can become completely sure what DEC intended. But when it's *all* no longer accessible, well that's a problem.

 

[dalmill]

I have the PDP1184-E User and Maint on microfiche.

Attached phone pics are from the System Overview chapter.

Dale