>  I was told by HP that as long as compression is turned off and I do not
> use a tape
> length that is invalid, I can create a tape to be read on a
> customers 2gb
> dds dat drive (dds1 or dds2).
>
> Is this info correct?

Yes; subject to the vagaries of misaligned heads and other
mechanism-specific problems, any tape written to the DDS or DDS-2 spec can
be read by any other drive capable of reading that format. Just like QIC, or
cassette tapes.

> Do you turn off the compression thru software or a hardware jumper?

Yes ;-)

The drives are normally set to allow software control of compression by the
host. If you want to, you can open up the case and change the settings on
the DIP switch (well, at least the C1533 mechanism has it on the bottom of
the mech). Many moons ago I had (and posted to the list) a description of
what each switch position does, but I don't seem to be able to find it at
the moment. Perhaps it's in the list archives. As an alternative, the
information at
  http://www.hp.com/isgsupport/pictures/t_rear.gif

may be of interest/value. It seems to indicate that setting position 2 of
the DIP switch to OFF permanently disables compression.

Steve