HP2648A tape drive capstans
rigdonj at cfl.rr.com
Sat Feb 4 22:38:06 CST 2006
At 11:19 PM 2/4/06 +0000, you wrote:
>> I'm a little curious--what kind of success might one have reading old (20+
>> years) HP tapes written on an HP9835? I was asked this recently and I
>> opined that based on what I'd heard, particularly from the HP calculator
>> group, that the chances of retrieving error-free data was not all that
>> Was I accurate? Or are the 98xx tapes an exception?
>Alas fairly low. The tapes for the 98x5 machines are much the same
>construction as those for the HP85. The problem is that the belt sticks
>to the oxide layer on the tape, and/or the tape sticks together, and you
>get major loss of the magnetic coating when you try to read the tape.
>Needless to say this makes it unreadable.
Tony's right. Two things can happen. First, reading the tape will cause
the media to shed but even worse is that if a tape is used with a gooy
capstan the goo will work it's way into the tape and gets wound up bewteen
the layers of tape on one of the hubs. Then it dries there and the next
time that you unwind the tape to that point the dried goo pulls the media
off the tape. I've also HEARD that some of the tapes also stick together
due to fungus, moisture or other things with the same results. You can
deal with the first problem by absolutely minimizing the tape useage. Read
each file then save it on another tape or drive. DON'T play around with the
drive and tape! As for the second problem I guess you could try
unwinding/rewinding each tape by hand to look for any sticking tape but I
haven't tried it. It seems like it would be pointless since you probably
coudn't do anything about it even if you found a stuck layer.
Also the HP-85 tapes and 98xx tapes are EXACTLY the same and have the
same PN. So are the ones used in the HP protocall analyzers, spectrum
analyzers, 2648 terminals and ALL HP products of that era except for the
big DC-600 type tapes used in the HP 9144, etc. They did use a different
tape in some earlier products but they were VERY different and immediately
recognizable. I have a couple of those drives but I've never seen a tape
for them. It was driven like an audio cassette tape via the hubs.
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