Re: imaging/duplicating HP tape cartridges - lots of questions


Paul Berger
 

The HP-IB command set for the drive is documented in the users manual so I would guess in theory you could use it to just read blocks of data from the tape, but I suspect that if the tape is physically damaged, such as when the drive band peels off some oxide you would not be able to read them.  It does say it supports SIF format and I think that is the format that 9825 uses.  The 9875 uses a  TACO to drive the tape drives, but since the TACO chip manages a number of the low level functions on its own, I suspect that it too would have problems with damaged tapes.  You could talk directly to it by replacing the processor card or writing custom code for the processor in it  (BPC only version of the processor in 9825), but it would probably take some probing to discover how to talk to the TACO.  For damaged tapes the best would probably be to talk directly to the drive and just capture the bit stream.  There is a good description of the SIF tape format in the 9875 users guide.  From what I can see in the manuals the drive units in the 9875 are the same as the ones in 9825/35/45.  There seems to be two versions of these drives, one that uses incandescent bulbs for light source for sensor and on that uses IR LEDs, the drives in both my 9825T and 9835A use the IR LEDs.   

Paul.
   

On 2017-02-20 12:58 PM, Jack Rubin wrote:

For archival imaging, no need, at least initially, to do anything with the bit stream other than to capture it. At that point, either one could attempt to read the image itself or else write it back to another tape, hopefully allowing the creation of a new generation of system tapes.

What would be the "best" FACT drive to use from the standpoint of reliability and ease of control?

Does any other machine that uses these cartridges have a richer command set that allows full tape duplication? Does the 9875 dual drive allow this?

Jack


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