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From: jch@omnigate.clarkson.EDU (Jeffrey C Honig)
Newsgroups: comp.unix.wizards
Subject: Problems with two UDA controllers in a MicroVAX
Message-ID: <7253@brl-adm.ARPA>
Date: Tue, 5-May-87 23:43:04 EDT
Article-I.D.: brl-adm.7253
Posted: Tue May  5 23:43:04 1987
Date-Received: Thu, 7-May-87 06:37:46 EDT
Sender: news@brl-adm.ARPA
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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.

Why is this code there?  Is it because someone assumed that the uVAX
will only ever have one controller, because of a Q-BUS limitation, or
because the uda controllers used in development of the MicroVAX (RQDXn)
support don't respond the same as a UDA50?

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.

Thanks

Jeff