9 track tapes and block sizes

Chuck Guzis cclist at sydex.com
Sun Oct 4 22:47:25 CDT 2020

On 10/4/20 8:12 PM, jim stephens via cctalk wrote:
> 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 couple of years ago, one of the NASA logging units turned up for not
much money.  Big flight case.  Basically consisted of a Kennedy
incremental drive (i.e. stepper) brought out to several BNC connectors.

My recollection is that the Kennedy 9000-series unit was NRZI and likely
800 bpi.   Unlikely that you could get 16MB on a 10.5" reel with that.
Probably unreadable on standard tape drives with limited formatter
memory.  I've also mentioned CDC 7-track "long tapes".

I've certainly seen the 9-track analog telemetry tapes also, but they're
a much different kettle of fish.


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