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From: bruce@think.ARPA (Bruce J. Nemnich)
Newsgroups: net.unix-wizards,net.dcom,net.lan
Subject: Re: DEQNA for MicroVAXen--help!
Message-ID: <5092@think.ARPA>
Date: Sun, 4-May-86 01:30:02 EDT
Article-I.D.: think.5092
Posted: Sun May  4 01:30:02 1986
Date-Received: Tue, 6-May-86 04:16:28 EDT
References: <16@mtxinu.UUCP>
Reply-To: bruce@think.UUCP (Bruce J. Nemnich)
Organization: Thinking Machines, Cambridge, MA
Lines: 27
Keywords: DEQNA, ethernet
Xref: watmath net.unix-wizards:17944 net.dcom:1862 net.lan:1456


I remember my DEQNAs coming (about 18 months ago) with a DEQNA manual
addendum that says two DEQNAs are not supported in a backplane yet.
Presumably this is becuase of a hardware bug.  This wouldn't surprise
me, since there are rather serious other hardware bugs in the DEQNA.

The most serious bug is that the device hangs every once in a while.
How often seems to be proportional to the general amount of traffic on
the net (not necessarily addressed to the card) and to the speed of
the processor (only 2 data points here, but it hangs with a KDJ-11
much more frequently than with a KDF-11), and quite possibly with the
length of the ether (much more frequent wedgings after doubling the
length of our ether from about 500-1000 feet).  The symptom I check
for in my driver is that a transmit command never completes--I check
it every 5 seconds, and do a device initialization if it appears hung.
The machine I am on now has hung and been reset 6 times in 310 hours
and 1.3 million packets.

There are other bugs with respect to handshaking flags in the Buffer
Descriptor Lists.  The bugs are either in the documentation or the card;
but they aren't too bad since one can program around them.



-- 
--Bruce Nemnich, Thinking Machines Corporation, Cambridge, MA
--bruce@think.com, ihnp4!think!bruce; +1 617 876 1111