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That will be the next round of debugging…

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Looking into the seek error

Both drives share the read and write logic, so we can continue with just drive 1.

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These can easily have to do with the quality of the tapes. tapes…

TU85 Tape problems

I have found a set of new old-stock tapes:

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This means the magnetic layer will have trouble there. It does not end there though; the magnetic layer itself has not really survived well either so it’s not that likely that we can actually read data off the tape. This is made worse by the fact that DEC TU58 tapes cannot be formatted: they came preformatted from the factory, and the TU58 firmware does not have any code in it that can format a tape. There is supposed to be firmware called tu58-i which can format- but the Internets do not seem to have it.

Let’s finish with some more images. This is a read that did several retries but ended with a seek error:

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I’m going to assume it has been repaired, but the tapes are unreadable..

Formatting TU58 tapes

There has been some discussion about whether a TU58 can be “updated” with new firmware to format tapes. Some discussions exist where people say that there was a “tu58-i” ROM for the machine which exposed a format command.

This, however, seems unlikely to me. The tape units in the tu58 do not have any optical sensors for the BOT and EOT tape holes, i.e. these:

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In other tape drives, like the HP drives used in the 9825A/B/T and the HP-85A, there is an optical sensor which can detect these holes. The TU58 cannot. And when the tape is rewound too far it will come loose from the wheel, as the tape is not glued or hard fixed on it: the tape gets stuck to the wheel solely by being wound on it.

For me this proves that formatting tapes is impossible on a TU58.

It should, however, be possible to format them using one of the HP drives…..