New find: pdp-11/05

From: Michael Robinson <>
Date: Fri Feb 14 01:54:01 2003

   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?
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

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.

If not, I guess we'll be looking for an H213-H216... :)

Michael Robinson
RPI Electronics Club Vaxherd/PDP-11 Fixer
Received on Fri Feb 14 2003 - 01:54:01 GMT

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