DEC MKA11 and/or M8261/M8163

Paul Birkel pbirkel at
Fri Feb 6 06:16:09 CST 2015

I don't understand the role of the M8162 "Port MUX A module" and M8163
"Port MUX B module" that the field-guide claims to be part of the MK11.
They aren't part of the MK11 as far as any documentation that I've read
regarding it.  At least the M8162 has a pair of 20ma-style SLU connectors
on it, but no UARTs that I can see.

Do these modules really belong to the MKA11, rather than the MK11?  Or to
something else entirely?

Is the MKA11 (which I can't find documented online) a revised MK11?  The
field-guide seems to imply this given its entry for the M8164 which
basically reads like this:

M8158       MK11                       U   Address buffer module

M8159       MK11                       U   Data buffer module

M8160       MK11                       U   Control A module

M8161       MK11                       U   Control B module

M8162       MK11                       U   Port MUX A module

M8163       MK11                       U   Port MUX B module

M8164       MK11/MKA11           U   Data buffer module (Replaces M8159)

It seems to me that something is incorrect in the field-guide, but none of
my researches have identified where the error is and what the right
answer(s) might be.

Anyone here have any experience/knowledge with/of the MKA11 and/or the

Thank you,


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