Wanted: SIMH VAX VMS tape image tester, take 2
jws at jwsss.com
Sat Dec 20 13:19:21 CST 2014
On 12/20/2014 8:19 AM, Al Kossow wrote:
> On 12/20/14 2:43 AM, Johnny Billquist wrote:
>> what are people trying to achieve
> Chuck is trying to embed metadata in tape image files.
> The only way to do this and be backwards compatible is to append
> a record to the end of the image.
> The argument is what the contents of that record should look like
> A magic string "TAPEINFO" as the first eight bytes of that record
> and colon separated keywords has been proposed for the rest.
> At a minimum, the actual container format and version
> the image is written in should be there
Might I ask what the end of the image is? Some tapes have and require
more than two EOT markers for a logical end of tape.
Maybe the TAPEINFO and some magic tag should be the very last bytes of a
tape image which has meta data, and an index in how much crap is at the
end of the tape for metadata also is included in that appended bit.
Then you just seek to end of file, look for the marker, then back up by
the length of the meta data to establish the end of the dataset.
I may have just stated the obvious though.
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