Nine track tape BOT sensing foil

Al Kossow aek at bitsavers.org
Fri Mar 2 08:52:29 CST 2007


 > After a recent fight with some Cipher tape drives,
 > trying to boot a system, I managed to badly mangle the
 > leader of my boot tape.

 > The BOT on a nine track is
 > just a hunk of sensing foil

True, but on tapes 1600 bpi and higher there is a burst
recorded over the BOT marker on one of the tracks to identify
the density. You obviously can't move the mark very far into
the tape without running into the first data block either, even
if you force the read density, which you can't really do on auto
loading Ciphers.

I have spliced new leader onto damaged tape before, using
analog tape splicing techniques (diagonal cut with two overlapping
pieces, then tape on the back). From memory, Cipher drives don't
have flux gates (little door over the top of the head). Thin clear
packing tape works OK, but don't plan on reusing the tape after you
get the data off.






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