Recovering data from 4mm and 8mm tapes

Eric Smith spacewar at
Tue Mar 24 03:30:06 CDT 2015

On Mon, Mar 23, 2015 at 9:59 PM,  <healyzh at> wrote:
> Not every DDS1 drive can read every DDS1 tape.  Not every DDS1 tape can be
> read in a different specimen of the same model drive as which it was written
> in.

I'm not disputing your statement in general, but I've apparently had
better results with DDS interchange than you have. I've used six DDS1
drives from four vendors and three DDS2 drives from two vendors, and
didn't have any interchange problems until one of the DDS1 drives
somehow became seriously misaligned. I believe this must have been the
result of physical trauma causing damage affecting the relative
positions of the head drum and the tape on the vertical axis (along
the width of the tape), or at least with a signifcant component on
that axis, because the track following servo should otherwise be able
to compensate for a fair bit of mechanical variation between drives.
When the DAT and DDS formats were designed, it was intended that they
be robust enough for good interoperation between drives without need
for any manual alignment of individual drives.


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