DEC boards unearthed - I have some info

From: daniel <daniel_at_internet.look.ca>
Date: Sun Oct 17 16:10:02 1999

-----Original Message-----
From: Tony Duell <ard_at_p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Sunday, October 17, 1999 2:54 PM
Subject: Re: DEC boards unearthed - I have some info


>> >> One of the other interesting items are a M7260/M7251 pair, one marked
>> >> "datapath", one marked "11/05 control". These are clearly the CPU for
an
>> >> 11/05, but will they go into an 11/04 or short (not BA-11) 11/34
chassis
>> >> for testing?
>> >
>> >You need the 11/05 (or 11/10 -- they're the same) backplane and
>> >frontpanel for these. There was a 5.25" box versions and a 10.5" box
>> >version with _different_ backplanes. They won't work in an 11/04 or
11/34
>> >backplane, though
>> >
>> >
>>
>> Actually the 11/05 and the 11/10 have two different backplanes (as I have
>> both) and the cards are fitted differently in each one. Keep your H214
>
>There are at least 3 different backplanes, but the 11/05 and 11/10 can
>use any of them. The 11/05 and 11/10 are really the same machine -- the
>differences seem to be what was included when the machine was originally
>shipped.
>
>The first backplane goes in the 5.25" box. The CPU cards go at the bottom
>(in slots 8 and 9).

No, CPU goes in slots 2&3, the maintenance board goes in slot 1.

The next 3 slots are for one set of core memory
>boards. And then 4 SPC slots, with Unibus out on slot 1 (top of box --
>yes, I do have this the right way round!).
>
>The second backplane is similar, and also goes in the 5.25" box. Again
>the CPU goes in the bottom. The next 6 slots are for 2 sets of core
>memory, with a single SPC (and unibus out) at the top (slot 1)
>
>The third backplane goes in the BA11-K 10.5" box. The CPU goes on the far
>right (slots 1 and 2). Unibus out is on slot 9 (as you'd expect). One of
>the A+B slots is for a paddleboard that connects to the the console
>cable. I can't remember how many core memory sets you can put into it.
>
>> 74 - if the back of the boards are green (solder masked)
>> 72/73 - if there is no baud selection switch
>
>Hmmm... They're strictly different systems -- the rotary switch implies
>it's an 11/05S board set. This has 2 extra features, firstly you can
>easily disable the on-board console port (if you want to use a DL11 for
>some reason) and secondly you can disable the unibus arbiter so that the
>CPU can be a slave device on the unibus of another machine.
>
>>
>> The best backplane I have is from someone who completely modified a PDP
>> 11/05 (16K backplane).He took out the second core memory set and
completely
>> hand wired the RK11-D on it. Yikes. It works and I still have the plane
if
>
>Seems reasonable. Modifying backplanes isn't _that_ hard if you are
>careful. I've done a couple of major backplane mods. The best thing to do
>is to make a wirelist and tick off each wire as you do it. Oh, and don't
>bother with one of those slit-n-wrap tools -- the general experience of
>those is that about 10% of the connections are actually good. Do the job
>properly, and it will work.
>
>-tony
>
Received on Sun Oct 17 1999 - 16:10:02 BST

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