9 track reel tapes

From: Nico de Jong <nico_at_farumdata.dk>
Date: Mon Sep 29 23:19:31 2003

> This one says Endura 800 BPI to 6250 CPI BASF
>
> It has an inner diameter of about 3.5" and an outer of about 7"
>
>
> A quick look on ebay last night turned up some disappointing results.

I've never had problems with BASF tapes, so that would be ok. 800 to 6250 means in fact that they can be used on all 9 track drives.
However, I dont think you can sell 7" tapes. The capacity is too limited,
A wild guess is that the tape length is about 600 ft = (600 x 12) = 7.200 inches.
Even at 6250 bpi and without interblock gaps, the capacity would be only 45 MB. As interblock gaps are 0.6" at least, a datablock of 6250 bytes would occupy 1.6".
So, 7200 / 1.6 = 4500 blocks = 28 MBbyte

Another example : datablocks of 1600 bytes would occupy (0.4 + 0.6) = 1.0"
Again: 7200 / 1 = 7200 blocks of 1600 bytes = 11.5 MB....

I've only _seen_ those tapes used in connection with software patches from IBM, and on data-entry equipment like the Mohawk . Horrible system.

My (biased) opinion is that _if_ 9-track tapes can be sold, it will only be the full size (2400 or 3600 feet)

Nico
Received on Mon Sep 29 2003 - 23:19:31 BST