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From: burton@parcvax.Xerox.COM (Philip M. Burton)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Help with 3COM Ethernet network and
Message-ID: <441@parcvax.Xerox.COM>
Date: Fri, 21-Aug-87 03:27:07 EDT
Article-I.D.: parcvax.441
Posted: Fri Aug 21 03:27:07 1987
Date-Received: Sun, 23-Aug-87 01:29:50 EDT
References: <18598J5U@PSUVM> <174200063@uxc.cso.uiuc.edu>
Reply-To: burton@parcvax.xerox.com.UUCP (Philip M. Burton)
Organization: Xerox PARC
Lines: 32

In article <174200063@uxc.cso.uiuc.edu> german@uxc.cso.uiuc.edu writes:
>
>
>One possible cuprit would the the interrupt level of the ethernet card
>conflicting with that of the COM port you are using.  I am not positive
>that the AT&T 6300's COM ports would use the same interrupt level, but
>on the IBM PC & PC/ATs COM1 is IRQ 4 and COM2 is IRQ 3.  You would probably
>want to use IRQ 2 on the ethernet cards unless that conflicted with
>some other piece of hardware in the machine. (3270 emulation cards for example)
>I have not tried your exact configuration, but this is the type of problem
>you run accross from time to time when dealing the PC networks.


Greg is absolutely right on.  Xerox has software that connects PC's to our
XNS networks, and we use cards supplied by 3COM.  We have run into a number
of compatibility problems that all come down to interrupt level conflicts.

The very first "Etherlink" card can be set for IRQ 3 and 5 only, but the
second (full length) and third (half length) allow any interrupt between
2 and 7.  Just be sure that your DMA settings are both one.

One other source of problems is the "DIX" setting (DEC-Intel-Xerox).  If you
are using "thin" Ethernet you must set the jumper differently than if you
are using standard Ethernet with a 15 pin drop cable.

Hope this helps.


-- 
Philip Burton
Xerox Corporation    408 737 4635
 ... usual disclaimers apply ...