9 track tapes and block sizes

jim stephens jwsmail at jwsss.com
Sun Oct 4 22:12:39 CDT 2020

On 10/4/2020 4:00 PM, Chuck Guzis via cctalk wrote:
> On 10/4/20 1:50 PM, J. David Bryan via cctalk wrote:
>> <snip>
> I don't believe that you're missing anything.   When I process these
> files, I mask off the lower 24 bits as the block length.  A 16MB tape
> block is impossibly large in any case.
> --Chuck
Oil logging tapes write 9 tracks with no inter record gaps or file marks 
till EOT.  I'm guessing you've not digitized any of those?

A friend built a custom machine which could be placed on site at the 
well site.  The tapes would be run to the unit, and then the data stream 
transmitted to a US based location for analysis.  Made necessary in 
Canada as they became very aggressive about transmission of such data.

In the 70's and 80s when this was in use it was very difficult to 
transport half inch tapes across the border w/o being challenged because 
customs was tipped off that the tapes were all potentially banned material.

I'm surprised that they have not turned up since they are useful for 
wells when trying to enhance output.


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