I found a few references to some 3490E talking about the recording density of 37,871 BPI

http://www.sunstarco.com/Tape%20Drives/Overland%20Data/Overland%20Data%20tapexpress_l490e.htm
http://www.archives.gov/records-mgmt/initiatives/transfer-regulation.html
http://webstore.ansi.org/ansidocstore/product.asp?sku=ANSI+INCITS+180-1990+(R2006)

There were many more.

I wonder if the differnce of 32K and 38K is user data vs user data +parity.

Rich Smrcina wrote:
So are you saying that Ditto lies?

R.S. wrote:

Robert Pelletier wrote:

Hi All. Question. Would anyone know the BPI of a 3480 cart running on
3480E drive (mock 3490). We have a request from a user to send us a
38,000 bpi cart. I swear they are 6250 bpi. Can anyone clear this up for
me? Where are they getting the 38,000? Thanks once again all.


<off-topic opinion>
Well, I have never bothered about BPI parameter, since IMHO it's completely irrelevant for the user. Cartridge capacity, mount time, rewind time are important.
</off-topic opinion>

Back to the question: CST cartridge contains 160m of tape. Uncompressed capacity in 36-track drive (3490E) is 400MB.
So 400MB/160m gives 25000 B/cm Inch is 2.54 cm, so the BPI is 63500.
CST in 3480 drive has 31750 BPI.

The values above are without compression.
I don't know exact length of tape and exact capacity, maybe it's not exactly 160m, however it seems the BPI can be approx. 32000. It rather cannot be 38000.

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