Pertec Tape Drive Interface Musings

Dennis Boone drb at
Wed Jun 10 13:31:28 CDT 2015

 > I particularly like the idea of being able to extract questionable
 > data and CRC/checksum.

That _would_ be really nice.

 > 1) Is it ever acceptable to mix densities on a single tape? I'm not
 > sure that my Kennedy drive will even allow that, but I don't know if
 > that is universal.

As others have indicated, portability of such a tape would be poor.

 > 2) What's the scoop on a final record overlapping the EOT marker? Or
 > even a new record starting after the EOT marker? I seem to recall
 > reading about some applications that stuck data after the EOT, such
 > as backup volume information.

I'll add two thoughts to the other answers:

1. The specs say there's supposed to be quite a bit of tape (10 feet, I
want to say) after the EOT reflector.

2. It was not unheard of for broken applications to run a tape clear off
the source reel.  The drive reports the passage of an EOT marker.  Few
systems enforce any behavior in this regard.  If you keep going, you
keep going.  At least until the tail comes off the source reel.


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