> > > What I'm surprised at here is the fact that noone seems to have mentioned
> > > that the VAX really don't see this as a SCSI controller.
> > > Anything you might have read about SCSI controllers just don't apply to
> > > what you have.
> > 
> > But, in the end it seems to work fine as scsi on the hardware via mscp.
> 
> Oh. The SCSI-controllers for Qbus (or Unibus) are usually pretty good. But
> from a software point of view they are not SCSI controllers.
> An easy comparision is the RQDX controllers, which actually use MFM
> drives, but they too are MSCP. MSCP controllers can use different
> technology in and to the drives.
> MSCP gives you another command set, more functionality, and a specific way
> of interacting with the controller.
> Thus, if you have an MSCP controller, you can exchange it for any other
> MSCP controller, and the software should stay the same.
> No matter if you are using MFM, SCSI, or SDI.

I am now aware of it as mostly a bridge between mscp and scsi.
It is a dilogic board, but I dunno whether it is disk only or disk and tape.
I will try to remember to pull the board and look up the numbers on it
tonight.

> > The joke is that none (read zilch) of my DEC drives will work correctly
> > on the silly thing.  But, by the graces, NON-DEC drives work fine after
> > I fiddled with the controller nvram settings.  What is it with these
> > silly DEC RZ56/57ish things?  Motor spinup is what it seems to be.
> 
> DEC is (was?) of the opinions that drives shouldn't spin up on power on.
> There is a specific SCSI command to spin up the drives.
> Some other vendors prefer to spin the drive up directly on power on.
> Most drives usually have a jumper to select how the drive should behave.
> Check your drives!

They are Micropolis drives rebadged for DEC as RZ56 or RZ57.
The other drives that worked were standard Fujitsu, from Sun machines.
I have run into this problem before with RZ 5x drives.

IFF ANYONE HAS the jumper settings (if they exist on these drives)
for motor-on and power-on spinup, do holler.

The drives work fine on all my pmax and xx3100 line VAXen, but not
on Suns or PC's or elsewhere.  Is there some detailed DEC specs
on the RZ56 and RZ57 drives, somewhere, as to jumper settings, etc?
Is it software coded?


> > > This is a MSCP controller, using the SCSI interface to hook up the
> > > drives. So the limits are defined by the MSCP protocol, as far as the OS
> > > is concerned, and by the mapping between MSCP and SCSI for the controller.
> > > 
> > > If this controller handles both tape a disks, it will actually look like
> > > two controllers to the VAX, since tapes are handled by TMSCP controllers,
> > > which are slightly different from MSCP.
> > 
> > OK, for the sake of discussion, I am having fits of problems with my scsi
> > TK50's trying to write tars for the MV2 TK70.  The Ultrix VS3100M38 box is
> > just not liking my available TK50 drives very well.
> 
> A 3100 have a real SCSI controller, so this is another ballpark.
> An easy way to check what you have is by looking at the system at bootup.
> Are your drives called "raX" and tapes "mtX", then you have something
> talking (T)MSCP. If they are called "sdX" and "stX" then you have pure
> SCSI.

My point was my TK50s are just not functional, very well.  I have 5 of them,
and now only 1 works.  The tapes fail to load, but they do pickup the leader
correctly.  It is where they seek to the start of the tape that fails.
The idiot lights for the tape start hole are clean, from what I can tell.
The tapes spin back and forth half a dozen times, after loading, then the
idiot light blinks fast red.  Then it requires 4 pushes to recycle the
thing to force unload (per DS3100 manual).


> There is no special trickery to SCSI termination in DEC equipment compared
> to any other equipment, that I know of. SCSI have termination rules.
> Follow them no matter what manufacturer you are dealing with.

OK, then, can a TKZ10 be used on a MVII off the dilogic scsi controller,
assuming it will talk to tape?

> > Continuing the sakes of discussion...., can an RRD42A cdrom drive be used
> > in a MV2 off the scsi bus?
> 
> Are we speaking of a MV2 or some uVAX3100 here?  

MV2 off the scsi controller, assuming it will use the RRD42A as a quasi
RZ disk.

> I think I read in atleast the CMD docs for a Qbus SCSI controller I have
> that it worked with the RRD40 atleast (about the newest thing existing
> when the manual was written).

That sounds like it might.

Thanks

Bob