2 Sep
2011
2 Sep
'11
2:36 a.m.
-----Original Message-----
From: Rob Jarratt [mailto:robert.jarratt at ntlworld.com]
Sent: 01 September 2011 21:44
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: RQDX3 DEVOFFLINE Problems
low-level
Sounds like the software has a problem rather
than the hardware. I
looked back at earlier posts; you said you tested the RD53 in a
MicroVAX 2000, and the RQDX3 in a BA23 uVAX II. But did that test use
the same
RQDX3 with the RD53 in the uVAX II? I /think/ the format put on an
RDxx by any revision of RQDX3 is the same, though new firmware might
change things like RCTs in ways not transparent to old firmware. But
the format used by
RQDX1 and RQDX2 is quite different to RQDX3 and I wonder if the drive
is the "wrong" format? Isn't a uVAX 2000 the same format as RQDX1/2?
The format did occur to me, but I thought that being readable in a 2000 it
would be OK in a II since the 2000 came later than the II. I have not formatted this RD53 as it worked in the 2000 without
issue once I had
unstuck
the heads. I will try the problem RD53 in my working
II and see if it is
readable
there. If not then I'll reformat the RD53 in the
2000 because I did this
once
before on an RD53 that I use in my working machine.
Just tried this, I put the RD53 that won't work into the BA23 and it worked
fine. So I think the M9058 must be faulty. I will see if I can identify a
faulty component on the board.
> The last possibility I can think of is that there are a few active
> devices on an M9058. They're mostly Schmitt triggers and
> open-collector inverters used to buffer signals from RQDX to drive
> (and v.v.), but some are differential buffers for the MFM data. Maybe
one
of those has gone.
Further thought on this suggestion is that it would be physically difficult
to achieve this because the M9058 has to be in a Qbus slot and it would be
impossible to connect the RD53 to the connectors as the cables I have are
way too short. I am not convinced that this test is worth the effort of
making some cables to fit because I have already eliminated everything
except the M9058, I think my best bet now is to check for faulty components
and see if I can buy or borrow a spare M9058.
You could of course test the M9058 in the BA23.
Just ignore the
BA23's normal drive cabling and connect the RQDX in the BA23 via the
50-pin cable to the M9058, and cable the drive to that as if it were
in a BA123. The M9058 has no connections to the backplane except for
power and won't interfere with anything else.
If the formatting things above do not work I will try
this. I am also
hoping to
borrow an M9058 from a friend, that may also help to
narrow down the
problem. There are not many ICs on the M9058 and most of them look to be
easily replaceable, but I would need to diagnose which one is the faulty
one.