New find: pdp-11/05

From: Guy Sotomayor <>
Date: Fri Feb 14 02:48:00 2003

On Thu, 2003-02-13 at 23:52, Michael Robinson wrote:
> Hello,
> Today a friend of mine acquired a pdp-11/05 from our school's
> engineering department. Unfortunately, it isn't in too good shape.
> Fortunately for him, I've spent the last three years restoring
> (sucessfully!) a pdp-11/45. So I offered to help. However, this machine
> is somewhat of a different animal, so questions:
> Could someone scan the engineering drawings for an H217C stack?

Go to or one or both will have drawings for
the 11/05.

> This is partly for my own edification (I have one such board in my
> machine), and partly because of the fact that this "new" pdp-11/05 has no
> core with it. Its engineering drawings seem to indicate that it wants
> 4 or 8kW of core (one or more of H213-H216), *not* the 16kW of a H217.
> (Granted, by placing two H214s into a chassis we get 16kW, but I
> digress.)

It will depend upon which backplane you have. If it's an 11/05-S
backplane then it's the same as what I have and you can go to to see how to use an
H217C (which is what I have in mine).

> That would have been enough to shut me up, but I looked a little further.
> It appears that the H213 (4kW) stack is a proper subset of the H214 (8kW)
> stack. The schematics appear to indicate that the H214 has all of
> the lines, bus connections, etc. as the H213, plus a few more. Indeed, it
> appears that if I were to place an H214 in the machine, but tell it that
> it was an H213, it would be fine (and see 4kW of course). Am I right?
> If so, the next question is, can I do this with an H217? (Drop in an
> H217C, and tell the machine that it's really an H214/H215.) This might
> sound like a gratuitous waste of core, which it is, but I happen to have
> another core board (not in my machine) that could be used... So anyway,
> the engineering drawings would answer this question really fast.

It's not so much the drawings but the wirelist for the backplane. You
really need to know which backplane you have.

> If not, I guess we'll be looking for an H213-H216... :)
> Thanks,
> Michael Robinson
> RPI Electronics Club Vaxherd/PDP-11 Fixer
TTFN - Guy
Received on Fri Feb 14 2003 - 02:48:00 GMT

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