TK70 tape drive media?

Patrick Finnegan pat at
Thu Jan 26 16:55:15 CST 2006

On Thursday 26 January 2006 17:33, Richard wrote:
> In article <200601262230.k0QMU7qR005246 at>,
>     "Zane H. Healy" <healyzh at>  writes:
> > > What do you use in this thing?  I've got a VAX 4000/300 with a
> > > TK70, but it didn't come with any media and I'm wondering what I
> > > should be looking for to feed it :)
> >
> > Compact Tape II's (aka TK70's :^)
> >
> > Might be easier to find a TK50 drive, and controller, or get a
> > CD-ROM hooked in there.  I have to question weather a TK70 is worth
> > the effort in this day and age, unless you're trying to *read*
> > tapes.  Sadly, TK50's are still worth the trouble, at least on a
> > PDP-11.
> That's kinda what I figured.  It looked like a weird DEC proprietary
> form factor for the media.  A quick google didn't turn up any obvious

If by "proprietary DEC formfactor", you mean "looks like a DLT tape", 
then yes.

BTW, just any old DLT tape (probably) won't work in the drive.  You need 
to find a TK50 or TK70 cartridge.  As Doc alluded to, you can maybe 
possibly probably use bulk-erased TK50 tapes as if they were TK70 
tapes, but it's a topic for a lot of disagreement... almost like "do 
3.5" HD floppies work reliably as DD floppies?".

> discussion of the media.  The machine has ethernet and I'm not sure,
> but it might also have a SCSI interface.  With ethernet I can get
> data into/out of the machine (heck, even the console interface can do
> that, but ethernet would be more expedient).

Depending on what OS you run, you may want a real QBUS ethernet card.  
I've had limited (read: horrible) luck using the onboard ethernet on my 
4000/300 with NetBSD.  I'm not sure if that's because of the controller 
design, or whether my machine has issues.  VMS might have better luck.

BTW, the male-HD50 "SCSI" connector on the 4000/300 is NOT SCSI, it's 
DSSI, and while somewhat similar electrically, they're nowhere near 
similar enough to be able to take a normal SCSI drive and connect it to 
the bus.  I tried that once, and ended up having to replace the 
terminator fuses on the CPU.  Also, NetBSD doesn't have DSSI support, 
partly because DEC didn't do a very good job of documenting it, and 
it's a fairly complex protocol, even compared to something like SCSI.

You might have a QBUS SCSI card though.  KZQSA's are somewhat common on 
the pedestal VAX 4000's for controlling a CDROM drive.... note that 
while that works OK with VMS, it isn't supported as far as I know under 
NetBSD, etc, and the interface was designed poorly enough that you 
can't reliably run more than about 1 (or maybe 2) device(s) off of it.  
You might also have a 3rd party SCSI controller, which *would* allow 
you to connect SCSI disks to it, and be supported under more than just 

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