RL02 woes

From: Patrick Finnegan <pat_at_purdueriots.com>
Date: Tue Aug 20 15:43:01 2002

On Tue, 20 Aug 2002, Tony Duell wrote:

> > > The drive is set to ID 3, because I don't have a '0' Ready light cover.
> >
> > Also never done that. Don't remember if it works or not. We were
> > always short of 0s and 1s (but seemed to always have a box of 2s and
> > 3s ;-)
> The drive will work fine if it has a '3' lamp cover and is the only drive
> connected to the controller. But you must have a 'ready' lamp cover
> fitted -- don't assume that if none is installed then the drive will
> default to 3. In fact, it won't work at all -- there's an extra contact
> in the ready lamp holder/select switch that detects that _a_ cover is
> installed.

Yes, it has the '3' ready lamp cover. I also have a 1 or 2 I think, but
definately not a '0'.

> The RK06/RK07 drives use identical covers, but they are numbered from 0
> to 7 (you can have up to 8 such drives on a single controller). These
> covers will work in RLs. The drive number is taken mod 4 in this case, so
> that cover 4 -> drive 0, cover 5 -> drive 1, etc

I'll remember that if I come across any.

> >
> > > Also, I don't have a terminator to use.
> >
> > Major problem.
> >
> Agreed.

I've found someone who will loan me a terminator (thanks Tom!), so once I
get that I can further evaluate the situation.

> > > Previously, when I connected a clock signal to the drive's clock in,
> > > which was anywhere near 4.2MHz, the fault light would go off.
> >
> > Hmm... interesting. Never played with RL drives at the signal level.
> > Not sure what that would do.
> One cause of 'Fault' is if the clock signal from the controller is
> missing. It's around 4.2MHz. But IIRC, if there's no terminator on the
> drive bus then the drive won't properly detect the clock (or any other
> signals from the controller) so you will get this error.
> Incidentally, the clock frequency is critical for running the drive (it
> determines the spindle speed amongst other things), but for testing the
> fault circuit it's not particularly critical.

That's what I thought... now if I run it at a differenct frequency, can I
get a different data rate out of it? I've thought about creating a
controller that is ISA bus or something, but needed the whole setup to do
any reverse-engineering, of course. Also, I've noticed it's hard to find
8.4 or 4.2MHz (or is it 8.2 and 4.1MHz?) oscillators.

> IIRC, the DEC cable doesn't connect all the pins (some are just not used)
> -- the RK06/RK07 uses a similar-looking cable with more pins wired.
> One of the corner pins is deliberately not bussed between the drives.
> It's a 5V output from the drive's PSU and is used to power the
> terminator. Needless to say, connecting 2 power supplies together is
> normally a bad idea. IIRC, though, it's a no-connect on the controller,
> so it shouldn't matter if you connect this pin on single-drive system.

On my PDF version of the RL Pocket Guide, it says that all the non-signal
pins are wired to ground... Hmm. There's a copy of it here:

I'll go home and check this with a multimeter tonight.

> >
> > > I also have tried reversing the cable to ensure I had
> > > pin 1 the same on both ends, to no avail (could that have nuked the
> > > interface on either the controller or drive?).
> >
> > No. DEC built their stuff to withstand upside-down and backwards
> > cables (but not modules - a former boss of mine watched an FE
> I will confirm that the RL's don't mind if you get the cable in
> upside-down. I've done it (using official DEC cables, etc) and never
> damaged anything.

Good. I just wanted to make sure I didn't make a big 'boo-boo'.

-- Pat
Received on Tue Aug 20 2002 - 15:43:01 BST

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