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Aucbvax.1982 fa.unix-wizards utzoo!duke!decvax!ucbvax!DEDWARDS@USC-ISI Mon Jun 29 16:02:09 1981 Re: IMP 11-B driver In response to the message sent 23 Jun 1981 1646-PDT from GeoffM@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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