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From: jbn@wdl1.UUCP
Newsgroups: net.wanted
Subject: Re: 4.2 BSD Driver For DUP11 Board (IBM
Message-ID: <659@wdl1.UUCP>
Date: Fri, 23-Aug-85 01:25:34 EDT
Article-I.D.: wdl1.659
Posted: Fri Aug 23 01:25:34 1985
Date-Received: Sun, 25-Aug-85 13:16:45 EDT
Sender: notes@wdl1.UUCP
Organization: Ford Aerospace, Western Development Laboratories
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Nf-ID: #R:riccb:-46800:wdl1:5900016:000:677
Nf-From: wdl1!jbn    Aug 20 16:54:00 1985


     Don't expect too much.  The DUP11 is a synchronous variant on the DL11;
it has one (1) byte buffering on both input and output, and thus must be
serviced every millisecond without fail at 9600 baud.  Not only is it a 
machine hog, there are interrupt lockouts longer than 1ms in 4.xBSD.  
     Some years ago I wrote a driver for this turkey for 4.1BSD for use with 
UNET.  It lost bytes above 600 baud, due to long interrupt lockouts in UNET and 
other parts of the system.  Interestingly, VMS drives DUP11 devices just fine,
but VMS has a less interrupt-lockout oriented internal architecture than Unix.
     You could drive it via a KMC, I suppose...

					John Nagle