FCO for KDA50-Q?

Johnny Billquist bqt at update.uu.se
Mon Nov 3 08:55:33 CST 2014

On 2014-11-03 15:12, Noel Chiappa wrote:
>       > From: Nigel Williams
>      > I have some Emulex SD590 drives which require a controller like the DEC
>      > KDA50-Q (M7164+M7165) or KDA50-QA.
> Can one really plug such drives into an Standard Disk Interconnect directly,
> or is the interface standard merely 'close'? (I don't know, merely raising
> the question.)

I know that other manufacturers did make SDI drives. I've had a few in 
the past. Can't remember what manufacturer, though. Might have been 
Emulex. Might have been SI...

>      > the KDA50-Q has a rather bad (show-stopper) bug that was fixed in later
>      > revisions, detailed here:
> I'm not sure that's a fatal issue; maybe it just causes the controller to have
> to re-read that last block? One could certainly write a hack work-around (re-read,
> extending the transfer size one block).

Most bugs I've ever seen have been minor things that didn't prevent 
operation. But it might degrade performance, or not provide correct 
information during error logging and such.
That said, I don't know what this specific FCO/ECO fixed. But if it 
really was a show/stopper, I would expect all KDA50s have had it applied 

>      > I need either revision D1 or D2 of the M7164 module. What should I be
>      > looking for on the board that would indicate it has had the FCO
>      > applied?
> Generally DEC indicates the ECO level by a stamp or something similar on the
> module handle(s) on the back side.

Sometimes. I would look for such information, but I would not take the 
lack of it as a sure indication of it not having a specific ECO level.
If it's just firmware, then the only clue might just be the part numbers 
on the EPROMs.

>      > joined with the 40-pin and 50-pin cables) along with the cab-kit up for
>      > sale
> The two short cables are pretty generic, from what I can see. Ground plane
> backing, but other than that, stock 40- and 50-pin flat cables. Those should
> be easy to make.

Yes. Bog standard short flat cables.

> The bigger issue is the cab-kit, which is almost unobtanium. There's a guy on
> eBay selling a bunch of NOS UDA50 board sets, which include a cab-kit, which
> is, I'm pretty sure, the same as the KDA50's - alas, the KDA50 User's Guide
> doesn't give the part number, so I can't be positive (the UDA-50 one is
> 70-18455-6K). Alas, he wants a ton of money...

They are not the same, but you can use it. The cable is the same, but 
the UDA50 one is usually much longer. However, the mounting plate and 
kit is different, since the mounting panel style is totally different 
between Unibus machines and Qbus ones. So you'll probably have to leave 
the actual plate will probably have to just lie on the ground or 
something. Less than ideal, but as I said - it will work.


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