IMP 11-B driver

[utzoo!duke!decvax!ucbvax!DEDWARDS at USC-ISI]

In response to the message sent  23 Jun 1981 1646-PDT from GeoffM at RAND-AI

The IMP11-A is DECs very old ARPAnet interface which was basically
two DR11s which knew how to talk 1822.  The IMP11-B is a totally new
device (circ 1978) which is based on the KMC11 microprocesor
which sits directly on the UNIBUS.  UUnfortunately, the IMP11-B
is a real bear to program, causes a lot of cycle spinning in
the UNIX driver because of its VERY STRANGE interupt structure
and command structure, and also has timing problems in talking
to an 11/70 UNIBUS.  I speak from experience, I have an IMP11-B
on my 11/34 through which I am now talking as well as one
on an 11/70.

Howard Weiss
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