Thanks, Brian.
If it is a tape that I wrote (and which then found its way to the CL to
be read at some point) it would have been ASCII files. And
ours was a 9-track.
I've heard the same thing about tapes needing to be exercised, and have
seen 1/2" tapes that are far less than 30 years old go
"bad" such that they can't be read by ordinary means. So
we'll see.
John
At 11:11 AM 3/26/2013, Brian Baer wrote:
Hi John,
Based on my hazy memories of the 80's. I have certainly not handled a
1/2" open reel tape in this century.
The MSU Perm. Tape ID doesn't necessarily mean it was create at the MSU
CL. It just means that it was stored there. If you needed the
information on that tape you would put a request in in your job control
to have that tape mounted, and assigned a unit number(?) before your
program ran to read or write that tape.
I would think that 6250 BPI is pretty much anyone that can recover a tape
needs to know. At some level these things are pretty standard. I think
they are 9 track with normally 8 tracks being data and the 9th being
parity.
Assuming this is some text based data I guess there is a 50/50 chance of
the data being ASCII or EBCDIC. Of course if the data is binary all bets
are off. I spent my first job at MSU writing programs to unpack
satellite data. I remember one data set had 10-bit bytes so it was packed
on the tape as 3 10-bit bytes per 4 8-bit bytes on the tape.
Of course tapes were never suppose to be stored for more than a few years
without be "exercised" -- basically run through a tape drive
and then rewound back to the original reel. The point of this was that
the data from the tape would have a tendency to bleed to/from the layer
of tape above/below it. When you took it off the reel and put it
back on again you were betting that the tape would be shifted a little
bit so that exact same bytes were not on top of each other to reduce the
effect of the bleeding. Don't know if this was really a problem or not,
but would worry about a tape that has sat in a drawer for ~30
years.
Anyhow my $0.05 worth.
Brian
On 3/26/13 10:40 AM, John Gorentz wrote:
Youngsters under age 50 can
ignore this message. It's only for old-timers.
If an old tape reel from the 1980s has a label on it that reads,
"Memorex Cubic 6250 BPI SuperReel" and a typed tag saying
"MSU Permanent Tap ID Number B 577" does that mean it was
created at the Computer Lab, as it was then called?
A former faculty member is interested in having a data recovery company
try to recover files from it. I've run the possibility past the
folks at werecoverdata.com (which I used a couple of years ago to recover
data from a crashed disk) and they didn't outright laugh at me .
But we need to supply information about the tape. Maybe 6250bpi
will suffice, but maybe other information about the system that would
have been used to write the data would be useful. Does anyone
remember the systems that would have been used to write such
tapes?
When the faculty member brought this up, I first thought she was talking
about a tape that I remember writing for her when she moved to Australia
back in the mid 80s. But I think our tape drive was a 1600 bpi
thing. I can't remember the model of the tape drive, but it was
purchased with an early VAX-11/780 computer. Googling has led me to
mentions of a model TU81, which is a model name I sort-of recognize, but
ours might have been older than that. But it probably doesn't
matter, because now this doesn't look like one of ours. I haven't seen
the tape at first hand. It's still in Australia or some such
place.
Any information would be appreciated, including any stories you know
about recovering data from tapes that old.
John Gorentz
