9 track tapes and block sizes

J. David Bryan jdbryan at acm.org
Mon Oct 5 00:51:34 CDT 2020

On Sunday, October 4, 2020 at 16:00, Chuck Guzis via cctalk wrote:

> A 16MB tape block is impossibly large in any case. 

The HP 3000 mag tape diagnostic attempts to write a single record from BOT 
to EOT, which unfortunately fails under simulation due to the 16 MB 
limitation.  In hindsight, it would have been better to accommodate record 
lengths corresponding to the highest density and longest reel length, which 
I think would need 28 bits.  Four bits for metadata identifier would still 
have been be good enough, and one of those should have been dedicated to 
"private data" that would appear invisible to programs running under 
simulation (and could be used to include information about the tape image 
with the tape image).

                                      -- Dave

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