Formatting Digital Tape


Does someone know how to format an 82161 digital cassette on an HP71B? The commands in the original manual are not described very well. Perhaps one needs a general decription of HP-IL.
Applying "cat:tape" get´s the response "invalid media" but the electric part may be ok.





the command is


but I don't have any other parameters here right now.



Hello Raymond,
thank you for your help. Now it seems to "format" the drive
(it winds it through two times) but the message "invalid media" appears again when I try to make "cat:tape".
So I think I have the common problem of "looking for a good tape"...




That is the usual message you get when you have bad media (tape). I have heard that most bad tapes are the felt pad but I have my doubts. I have some that behave this way, and the felt pads are great condition.

Very many of these old tapes are bad. I'm not sure what the percentage is but I have more bad ones than good ones.


I think it´s the common problem with the tapes, too. But I am happy that my drive seems to be ok. Now I can try to refurbish the tapes like mentioned some threads before.
I think the pad is ok and has enough pressure from the bronze plate.
Sometimes I have the impression that the HP calculator and computer equipment (ref. the "gummy wheel problem") is simple consumer quality which is not comparable to the high standards of the measurement equipment.
But it´s both nice to refurbish and to play with :)




When the pressure pad in a 82176 cassette fails, it's not the felt that goes, it's the foam pad under it. The felt will still look fine -- it is fine.
But it's not pressed against the tape properly. Try moving the felt around with a pointed tool. If it almost falls off, then the foam has decayed.
I've handled many cassettes in the HPCC library, and I think I've seen one with tape problems (flaking-off oxide), about 10 with pressure pad problems, 5 or so where the tape has separated from the leader and a couple with BOT/EOT mirror problems.


Hi Tony,

you are right, the felt is some sort of spinning around in the holder. But I thought it gets pressed by the read/write head. I will try to replace it from a part of a normal Cassette. Do you have any hints how to open the HP cassette without destroying it?

Bye... Stefan


To open the HP cassettes, I normally use a non-magnetic tool (e.g. the handle of a cotton bud) inserted in the small square holes at the ends of the 'window' side of the cassette. And then prise (pry) the housing apart. Once it's started to separate, I run a finger nail (or if it's really well stuck, a thin blade) round the joint.
Always dismantle these cassettes label-side up. The case halves are not identical, and the bits stay in place better if you do it that way.
I replace the pressure pad with a piece of felt stuck on a double-sided adhesive foam pad (Maplin sell (sold?) them in the UK, called 'Quickstick pads).
As I mentiond a short time ago, I have an article I wrote for DataFile describing how to repair these tapes. My web browser won;t let me include it in a posting like this, but I'd be happy to ftp it, or e-mail it somewhere. Is there some way it could then be posted to the articles forum here?

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