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From: durham@w2xo.pgh.pa.us (Jim Durham)
Newsgroups: sci.electronics
Subject: Dec Drive Mystery
Keywords: RD53 DEC DRIVE
Message-ID: <140@w2xo.pgh.pa.us>
Date: 30 Mar 91 21:06:33 GMT
Organization: Jim's Basement, Gibsonia, PA
Lines: 23

This is a long shot, but I thought I'd try this group, as most of
the 'computer' groups are software types and this is definitely a
hardware question:

On a DEC RQDX2 disk controller, the controller 'knows' when you are
using an 'official' DEC drive (RD52,RD53). These are ST-506 drives
that work just fine in PCs or whatever as ST-506 drives. The reverse
is *not* true, you can't put another brand of ST-506 drive on the
DEC controller. Even if the physical characteristics of the drive
are the same; ie; number of heads, cylinders, etc. WHY? How do it
know? It refuses to acknowledge the existance of anything but
an 'official' DEC drive.

There is a parameter block that is written out to the drive that
will not allow one simple format program to work. I am aware of this.
This isn't the problem.

Anyone ever run into this and maybe *know the answer?*. I really don't
want to buy another 71 meg drive just because the controller needs
some edge connector pin tied high or some such thing.

Thanks for reading!
-Jim Durham  (durham@w2xo.pgh.pa.us)