From: Charles H Sauer <sauer@technologists.com>
To: tuhs@minnie.tuhs.org
Subject: Re: [TUHS] PL/I stuff - was: Book Recommendation
Date: Sat, 27 Nov 2021 09:53:10 -0600 [thread overview]
Message-ID: <1ae0c3f8-fc2b-84a9-442b-e591dca591fd@technologists.com> (raw)
In-Reply-To: <20211127152527.591D518C07B@mercury.lcs.mit.edu>
On 11/27/2021 9:25 AM, Noel Chiappa wrote:
> > From: "Charles H. Sauer"k <sauer@technologists.com>
>
> > I haven't done anything with 9 ktrack tapes for a long time ...
> > I don't recall problems reading any of them. ...
> > IMNSHO, it all depends on the brand/formulation of the tape. I've been
> > going through old audio tapes and digitizing them
>
> The vintage computer community has considerable experience with old tapes; in
> fact Chuck Guzis has a business reading them (which often includes converting
> old file formats to something modern software can grok).
>
> We originally depended heavily on the work of the vintage audio community, who
> pioneered working with old tapes, including the discovert of 'baking' them to
> improve their mechanical playability. ("the binder used to adhere the magnetic
> material to the backing ... becomes unstable" - playing such a tape will
> transfer much of the magnetic material to the head, destroying the tape's
> contents.)
The notion of "baking" is slightly misleading. When done with audio
tapes, the practice is to use a dehydrating oven at about 130F for about
24 hours.
> It's amazing how bad a tape can be, and still be readable. I had a couple of
> dump tapes of the CSR PWB1 machine at MIT, which I had thoughtlessly stored in
> my (at one period damp) basement, and they were covered in mold - and not just
> on the edges! Chuck had to build a special fixture to clean off the mold, but
> we read most of the first tape. (I had thoughtfully ade a second copy, which
> read perfectly.)
>
> Then I had to work out what the format was - it turned out that even though
> the machine had a V6 filesystem, my tape was a 'dd' of a BSD4.1c filesystem
> (for reasons I eventually worked out, but won't bore you all with). Dave
> Bridgham managed to mount that under Linux, and transform it into a TAR
> file. That was the source of many old treasures, including the V6 NCP UNIX.
>
> Noel
>
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next prev parent reply other threads:[~2021-11-27 15:55 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-27 15:25 Noel Chiappa
2021-11-27 15:53 ` Charles H Sauer [this message]
2021-11-27 15:58 ` [TUHS] tape "baking" [was " Charles H Sauer
2021-11-27 16:07 ` Steve Nickolas
2021-11-27 17:39 ` Al Kossow
2021-11-27 17:42 ` Al Kossow
-- strict thread matches above, loose matches on Subject: below --
2021-11-24 23:54 [TUHS] " Douglas McIlroy
2021-11-25 16:35 ` Paul Winalski
2021-11-25 18:15 ` Steve Nickolas
2021-11-26 16:59 ` Paul Winalski
2021-11-26 20:30 ` Tom Ivar Helbekkmo via TUHS
2021-11-26 21:22 ` John Cowan
2021-11-27 0:01 ` George Michaelson
2021-11-27 16:12 ` Paul Winalski
2021-11-16 14:57 [TUHS] " Douglas McIlroy
2021-11-23 2:28 ` Mary Ann Horton
2021-11-23 21:54 ` Thomas Paulsen
2021-11-24 15:18 ` Richard Salz
2021-11-24 22:19 ` Charles Anthony
2021-11-24 22:29 ` [TUHS] PL/I stuff - was: " Will Senn
2021-11-24 23:00 ` Rob Pike
2021-11-24 23:13 ` Richard Salz
2021-11-25 1:48 ` Nelson H. F. Beebe
2021-11-25 2:03 ` George Michaelson
2021-11-25 14:47 ` Clem Cole
2021-11-26 22:20 ` Alan Glasser
2021-11-26 22:33 ` Alan Glasser
2021-11-27 0:23 ` Dennis Boone
2021-11-27 0:30 ` Larry McVoy
2021-11-27 0:47 ` Charles H. Sauer
2021-11-27 2:43 ` Alan Glasser
2021-11-27 0:56 ` Warner Losh
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