Frank Gribbin wrote:
>
> Hi Art,
>
> Our SHOWDEV once reported a tape with none loaded.
> It disappeared with a START NORECOVERY.

AFAIK, :SHOWDEV has never detected the "absence" of a tape unless it was
explicitly closed by MPE.  Well, wait, that doesn't quite explain what I
mean.

Mount a tape in a DDS drive.  The system performs AVR (Auto Volume
Recognition) and you get tape message saying a tape has been mounted on
ldev#x.  Showdev will confirm this.  Now press the unload button and
take the tape out.  No change in :showdev status.  Nothing "informs" the
system that the tape has been removed.

Likewise, if you restart the system with a tape mounted and online, when
MPE comes up, showdev says it's available.  No AVR to pick it up.

This was true way back to 9-track 1600bpi days :-)

I know this because we used to have a 7980 (HP-IB) shared between two
systems (we had HP's HP-IB "A B C switch).  You had to insure that the
corresponding ldevs were "AVAIL" on both systems and nothing in the
drive before throwing the switch, else "unpleasant things" could happen.

Jeff

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