Question about PDP-11/70 backplane

[Ioncannon]

Earlier I talked about my interest in the PDP11. I got a few cards for the CPU cabinet (still need a lot more) but I am having trouble figuring out which backplane I need. The installation manual mentions part 7011051 Rev D for the KB-11 C Processor. Is this the part I am looking for? Do they go under another name?

 

[RSX11M+]

Well, you're mighty ambitious.

7011051-D is for the backplane only... no box or power supply. It's referenced separately so that you can be certain to get the correct revision, which is critical for a KB11-C and FP11-C.

You'll be best off if you can locate a decdatasystem-570. The older cabinets will present problems, especially if they were not maintained.

• It has the KB11-C Processor Cabinet
• 30A - 3 Phase Power Supply [QTY=2 H7420]
• UNIBUS I/O Backplane
• various other goodies like power controllers/sequencers
• MK11 Memory [Separate cabinet] unless you happen to have PEP-70 memory

You'll probably want to think about a MASSBUS device or two.

I don't recall any actual cpu box designation because that's all it's good for. A quick look at the installation manual leaves me with the same conclusion. I can look for another designation on the print set if you like, but I think it's only likely to be good as trivia.

 

[Ioncannon]

I understand it's backplane only, I was thinking of building from the ground up over a long period rather then buy a whole system at once (not in my price range). Maybe I am going about this at the wrong way?

If I could find the CPU cabinet /w backplane that would be even better but don't see them appear that often (usually in pieces).

 

[Qbus]

M8631ca???

M8631ca???

Look on EBay under CNC systems, have seen couple PDP-8 for under 1K and I bought a PDP 11/23 that was built around a H9281 backplane that came with a power supply, 8186 cpu, a CA dual port com card and a flock of A to D boards for under $50 so the stuff for building your own is out heir. Incidentally this came with a M8631CA that appears to be a multi function card and if anyone has any idea what that is please share.

 

[RSX11M+]

M8631-CA MCV11-DC Q 16-Kword 16-bit 2k x 8 static CMOS RAM with 96-hour
M8631-CA battery backup (Also M8631-CF, -CL). Q22.
M8631-CA Refs: EK-MCV1D-UG, EK-MCV1D-RC, MP-01309

Doesn't sound like your description though..?

 

[RSX11M+]

I was thinking of building from the ground up over a long period rather then buy a whole system at once (not in my price range). Maybe I am going about this at the wrong way?

I wasn't trying to discourage you... but from your post I had to wonder if you knew what it would entail.

Just "feeding" a pet '70 is daunting enough to discourage many, even if they were giving them out free on street the corner.

Certainly, a complete system is most desirable, mostly because you won't need to discover what's missing. Also, complete systems will be the most economical ones to get, in fact they're usually free for the taking. [except you have to pay to rent the truck] A '70 of the type I suggest is about the size of 2 California king size beds with box springs piled on top of one another, and turned on it's side lengthwise. Weight is about that of a mid-size car.

I am reminded of the story of the fellow who found a bolt lying on the side of the road, and decided to collect the remaining parts until he had the original object it came from.

The bolt was a 747 engine pylon fastener.

 

[Ioncannon]

heh RSX, I would LOVE to get my hands on a complete system (free too? YEA), and have a trailer so transport would be no prob, however I don't think I'd have a good chance finding one in Toronto. Closest I got was my University had a PDP-11/70 rack, but they threw it out before I could get to it.

 

[RSX11M+]

heh RSX, I would LOVE to get my hands on a complete system (free too? YEA), and have a trailer so transport would be no prob, however I don't think I'd have a good chance finding one in Toronto. Closest I got was my University had a PDP-11/70 rack, but they threw it out before I could get to it.

Chase it to the salvage.... you never know.

 

[RSX11M+]

11/70 Service Contract Configuration Documentation...

11/70 Service Contract Configuration Documentation...

Tonight, while scouring my archives for something else, I ran across a folder marked in huge bold letters...

Do Not Remove
From The Computer
Room!!!

Of course, it's no longer with my missing 11/70... apparently I grabbed it when I discovered the machine was to be decommissioned.

This book contains the DEC Service Contract details for our systems that were under contract, among them the 11/70.

The point....

In scanning the information I see much to my surprise, in the configuration section, the system CPU cabinet "BOX Type" is recorded as a BA11F

I report this fact, for what it is worth.


...and just in case God is listening... The system serial number is recorded as 32825... please if there's someone out there who knows what happened to it, guide them to post here?
​

 

[RSX11M+]

Two notes:

First to God - If my '70 is still out there, please tell the current owner that the unexplained system hangs I could never figure out may have to do with this note I recently found from 1994...

If your 11/70 is a KB11-B or was field-upgraded to a KB11-C, you may have an M787 KW11 clock in slot 1. The M787 module must be CS "D" or higher. Older modules may generate spurious requests at priority level 6, which can hang the machine. Quick check - DEC 8881's instead of DEC 381 IC's on module.
​

I realize now that I am probably responsible for this problem. In the first years I was working with the 70, I added a license for SPM [System Performance Monitor] in addition to upgrading our RSX license to M-PLUS. One hardware requirement to run SPM was the addition of a KW11 clock module. I seriously doubt the issue was known when I did this, which would be 1984, and I'd bet dollars to donuts that the module I bought and installed was an insufficient rev and introduced this problem. The hangs occurred unpredictably, but usually 2 times a month or so with 24/7 operation.

P.S. - I miss that machine.
​

Second - To your 11/70 backplane question...

I found a reference to the H960-cabinet as an 11/70 cabinet, and suddenly, this rings a bell with me. With 32 - 4" fans, it pretty much has to be the CPU box.
​

 

[marmotking]

I have an 11/70

I have an 11/70

I think it's pretty much complete. However, I've not had the time to try and fix it up. It's in a bit of a mess. I imagine it will be quite the restoration project, but it is supposedly all there. I have an 11/45 to go with it, which was supposedly working when it was decommissioned by the owner before the owner before me. I've been side tracked lately on a VAX 11/750, which is my all time favorite machine. It too needs some work. I got the 11/750 for free. I had to pay about $700 for the 11/45 and 11/70 together. Not bad, but they're a little rough. What I really need is to find someone who lives in my area who really knows a lot about these machines who might be able to give me some pointers. I have no problem with the 11/750, but the 11/70 and 11/45 are going to be a real challenge.

 

[RSX11M+]

I think it's pretty much complete. However, I've not had the time to try and fix it up. It's in a bit of a mess. I imagine it will be quite the restoration project, but it is supposedly all there. I have an 11/45 to go with it, which was supposedly working when it was decommissioned by the owner before the owner before me. I've been side tracked lately on a VAX 11/750, which is my all time favorite machine. It too needs some work. I got the 11/750 for free. I had to pay about $700 for the 11/45 and 11/70 together. Not bad, but they're a little rough. What I really need is to find someone who lives in my area who really knows a lot about these machines who might be able to give me some pointers. I have no problem with the 11/750, but the 11/70 and 11/45 are going to be a real challenge.

Love to help you, but Seattle is a bit of a trek for me. What's your major need?

 

[marmotking]

No need yet, as I haven't started. However, when I do sometime later this year, I'll make sure to very carefully document and photograph as I go. I want to be very, very careful about this.

 

[RSX11M+]

That will be excellent... photos will help immensely.

In fact, if there's any way you could take a few beforehand, I can begin to gather documentation in advance and perhaps "bone up" a bit in preparation.

• What kind of storage does it have or were you planning?
• Any idea which version you've got?
• Power needs?

...anyway... sounds like fun. I'll be watching for your posts.