On Jun 10, 22:19, Jerome H. Fine wrote:
> >Pete Turnbull wrote:
>
> > > On Jun 8, 19:18, Jerome H. Fine wrote:
> > > Controller Model Max RD5n Drive
> > > RQDX3 (M8639-YB) RD53
> > M8639-YB is not RQDX3, it's RQDX2.
>
> YOU ARE CORRECT!! I did not check the details enough!!
> I almost always seem to have at least ONE typo in anything
> over 50 words.
:-) I have that trouble too.
> And even the RQDX3 is difficult
> to use with any MFM drive except DEC RD5n and DEC RD3n
> drives. As for the RQDX1 and RQDX2, I don't ever seem to
> remember seeing one without a real DEC drive, although I have
> heard that XXDP has been patched to use a non-standard (i.e.
> non-DEC MFM drive). With regard to being able to FORMAT
> a drive with an RQDXn controller, normally special XXDP programs
> from DEC are REQUIRED!
The RQDX1 and RQDX2 do tricks at startup to try to figure out what kind
of drive they have connected (things like selecting unusual head
numbers, seeking to high-numbered tracks) and if the results aren't
what they expect, they won't recognise the drive. You can use many
non-DEC 10MB drives with an RQDX1, given a suitable (early) version of
the ROMs, but other sizes are tricky (and a drive that works with one
version won't necessarily work with another). All the relevant drive
parameters are fixed in the RQDX1/2 firmware.
Things are much easier with the RQDX3, as it stores the drive
parameters on the drive, so if you can once format it, it works. The
table of values for approved drives is in the formatter program. In
the later versions of the RQDX3 firmware, there is the capability to
accept a new table entry from the formatter, and later versions of the
XXDP formatter (ZRQCG0 and later) allow you to feed it values. If you
do that, you also have to tell the formatter NOT to read the defect
list (because there isn't one on a non-DEC drive, and when it tries to
read it near the end of the 15-30 minute format operation, it will fall
over). Working out the right values, however, is non-trivial. I've
done it twice. The first time, in about 1990, it took days to work out
what some of the entries meant. Now I just use drives it knows about
already.
You can also format a drive on an RQDX3 on a Vaxstation with VS2000
diagnostics. I don't know if that lets you bypass the UIT (Unit
Identifier Table) as well, but I expect so.
--
Pete Peter Turnbull
Network Manager
University of York
Received on Fri Jun 11 2004 - 02:23:30 BST