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From: ed@mtxinu.UUCP (Ed Gould)
Newsgroups: comp.unix.wizards
Subject: Re: Problems with two UDA controllers in a MicroVAX
Message-ID: <426@mtxinu.UUCP>
Date: Wed, 6-May-87 17:09:43 EDT
Article-I.D.: mtxinu.426
Posted: Wed May  6 17:09:43 1987
Date-Received: Sat, 9-May-87 01:47:27 EDT
References: <7253@brl-adm.ARPA>
Reply-To: ed@mtxinu.UUCP (Ed Gould)
Organization: mt Xinu, Berkeley
Lines: 51

>I just purchased a Systems Industries QDA4EC/4382 combination.  The
>controller emulates a UDA/KDA50.  I'm installing it on a MicroVAX-II that
>already has an RQDX3/RD54 combination running BSD 4.3 Unix (Mt Xinu's
>43+nfs).
>
>I generated a system to support the current rqdx3/rd54 disk AND the new
>controller/disk.  The new disk is not yet installed but I booted anyway
>to check the configuration. I was very surprized to watch it configure
>uda0 and uda1 at the same address (172150). I wasn't that surprized to see
>the system lock up after that point though.
>
>After rebooting my old vmunix I looked at the uda driver code.  It has
>a section of conditional code delimited by VAX630 (i.e. MicroVAX) that
>checks for (cpu == VAX_630) and assumes that there is one controller at
>172150.  Normally this code would init the controller at the gened in
>address and wait for it to initialize.

No such code exists in our distribution.  Perhaps someone at your
site added it?  Guessing, I might think that it was added because
the DEC controllers take an annoyingly long time to initialize.
Since the microvax was almost certainly bootstrapped with the same
controller, then maybe someone thought they could avoid initializing
it again.  I have no idea if this will really work, or if it is why
the code was added, but it sounds plausible to me.

>If it is not a limitation of the Q-BUS, but of one of the DEC
>controllers I belive I could modify the code to assume that a
>controller at 772150 is a dumb controller and controllers at other
>addresses respond the same as a UDA50.  If it is a limitation of the
>RQDX1 or 2 I can take the code out or add conditional compilation if an
>RQDX1/2 is present.

The second mscp controller on a microvax is usually addressed at
0160334.  We have run systems with two controllers, but have
occasionally had difficulties configuring DEC RQDX[23]s as the
second controller.  Other manufacturer's controllers configured
second seem to work correctly.









-- 
Ed Gould                    mt Xinu, 2560 Ninth St., Berkeley, CA  94710  USA
{ucbvax,decvax}!mtxinu!ed   +1 415 644 0146

"A man of quality is not threatened by a woman of equality."