i highly doubt this would work. The TK50 interface is pretty simple, and
the controller is most deifnitely a controllER and not a controllable device.
it isnt just passing packets, it is sending commands to advance the tape, 
write bits, etc, i suppose an analogy would be the SCSI ESDI and MFM 
controllers you used to see (there were found in lots of sun boxen) where the
disk is ESDI and theres an ESDI controller with a scsi adapter 
controlling it, and tlkaing to the scsi bus to the outside. it only goes 
one way.. 

isildur

On Thu, 14 Jun 2001, NetBSD Bob wrote:

> > > That is a normal TK50 (or at least all the ones I have are).  But, inside
> > > that box is a scsi-to-tk50 controller, that converts the relatively
> > > normal scsi1 to native tk50speak.  I have used the transports
> > > interchangeably between the TKQ50 and the scsi outboard boxes.
> > > They all seem fine, to me.  The transport even has the black
> > > plastic slide-in tray that the BA23/BA123 boxes use.  All mine
> > > are -GA marked.
> > > 
> > Very interesting!  Has anyone ever tried to use this in reverse?  Like
> > hang a scsi tape drive or disk off a tk50 controller with the converter in
> > between?
> 
> Gee, a real, ``Aw doggiedoo, EUREKA!''.  That would sure be a neat way
> to get a scsi tape drive to work off a TKQ50 controller, IFF it could
> be made to work.
> 
> I am all ears on this one..... and I do have a spare board at home
> that I might could try it on.
> 
> Anyone know of any for-sure gotchas in that sort of approach?
> 
> Theoretically, I would expect it to be possible.  Practically, dunno.
> 
> HD's would probably not work, but tape drives might?
> 
> If that could work, one could hang a scsi 9 track reel deck, or
> maybe an Archive 150mb viper off a TKQ50 card.  My, my, how
> interesting that would be.....
> 
> Someone mentioned they had some TK50 manuals aound?  What about
> for that scsi controller card?  Is it an Emulex thing like was
> used in the Sun systems (3/160 VME chassis)?  The board does not
> look like Emulex built, but more straight DEC built.
> 
> Anyway, food for tinkering.....
> 
> Crazy... maybe?  But.....
> 
> Bob
> 
>