150 Mb tape drive question

[Jim Reilly]

I have a question about our Sparc stations (150 Mb) tape drive, well
actually about the tapes.  The tapes (Sony QD-6150) are 620 ft, 12500
ftpi.

What does ftpi stand for ?  I've assumed it means bpi, and that the
calculation for how much can be stored on it is:

(600 ft)(12500 bits/in)(12 in/ft)(18 tracks)(1 byte/8 bits) =
          202500000 bytes

which should roughly hold 150 Mbytes of real data.  Am I correct, or
hopelessly wrong ?

(please respond to reilly at tel.vtt.fi, as I don't read Usenet too often)

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