Cartridge tape compatibility

[Jamie Watson]

I seem to have fallen behind the cartridge tape market again.  A number
of manufacturers are now shipping systems with cartridge tape drives
that are higher than 60 Mb.  I've heard claims of 120 to 150 Meg.

What is the story on these drives, and the media they use, in terms of
compatibility with existing QIC-24 tapes, as found in Sun, IBM RT/PC,
NCR Tower and others?  Can the new drives read QIC-24 tapes?  Perhaps
by some stroke of luck, the old drives can read the new tapes, up to
some limit of length, as was the case when we went from 20Mb to 45Mb?
What about the cartridges?  Lately I have started seeing (or noticing)
two different maximum recording densities specified on cartridges -
some say 10000 ftpi, others say 12500 ftpi.  Perhaps the new drives
will only use the higher rated tapes?  I hope not, or at least I hope
they have a way of sensing, and using at lower density, the 10000ftpi
cartridges.

Failing all these frail hopes of compatibility, are there any systems
available today which can read (and write?) both formats?  The RT/PC
can read both QIC-24 and QIC-11, and automatically detects which is
present.  Sun can read/write QIC-11 on rst0 and QIC-24 on rst8.  It
would at least be some consolation if something similar happens with
the new higher capacity units.

jw