KL10-A/KL10-B differences

Noel Chiappa jnc at mercury.lcs.mit.edu
Mon Jul 8 14:29:57 CDT 2019

So I'm a little puzzled by something, and I was wondering if anyone
here knows the answer.

So early KL10's (KL10-A's, to be precise) only support a single DTE20, and
no RH20's. Later ones supported up to 4 of the former, and up to 8 of the

I always supposed this to be part and parcel of the 'Model A/Model B' CPU
difference, but no... EK-0KL10-02 Part 1 (no title, seems to be notes for
F/S) pg. 9, says both KL10-A and KL10-B's are PA (DEC jargon for the Model
A CPU - below), but the former has no RH20's, the latter does.

(A note at the bottom of the page says that a PA is a 'Model A', and
describes it as having "internal channels". The PV is a 'Model B' -
extended addressing, larger ucode, faster clock.) 

So my new theory is that it's the MBox (either the backplane, the boards,
or the wiring from it to connectors, etc) that is the difference between
the KL10-A and the KL10-B.

Can anyone confirm this and/or provide details of the differences? Pictures
of the MBox in a KL10-A would be good, too.


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