13 Jan
2018
13 Jan
'18
6:20 a.m.
So why are reels of DECtape selling for unbelievable prices on eBait? See,
e.g. here:
https://www.ebay.com/itm/372186744906
and here:
https://www.ebay.com/itm/372186745609
I can't believe there are hordes of TU55/TU56 owners out there who desperately
need media; so what is it? People who think DECtapes were super cool and have
to have a reel, even though they don't have a drive? Or are there actually
TU55/TU56 owners (remember, it takes two bidders to put the price up) who
really need media?
Anyway, it looks like this person:
https://www.ebay.com/itm/202183912961
who got four for the 'bargain' price of $80 got a 'deal'!
Noel
13 Jan
13 Jan
6:34 a.m.
So why are reels of DECtape selling for unbelievable
prices on eBait? See,
e.g. here:
I had those on my watch-list and just shake my head at the astonishing
prices for the things.
I've wondered if you might not make DECtape tape from 3/4" video tape.?
I know that DECtape has mylar on both sides but what if you somehow
glued two strips of video tape together with the mylar backing on the
outside.? Probably want to build a jig of some sort and I'm not sure
what glue to use.
8:52 a.m.
So, where were all these people when I was trying to clean out
my old house a couple years ago? I threw out piles of tapes of
various formats because I couldn't find anyone to take them for
postage. I also threw out piles of other stuff (some of it old DEC
and Sun kit) after offering it on eBay and getting zero bids. The
only thing I have successfully sold thru eBay was an antique
claw-foot bathtub. I have stuff now that will likely go in the trash
because I really can't affords the space to be a storage locker
any more.
bill
________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of David Bridgham via
cctalk <cctalk at classiccmp.org>
Sent: Saturday, January 13, 2018 9:34 AM
To: Noel Chiappa via cctalk
Subject: Re: DECtape madness
So why are reels of DECtape selling for unbelievable
prices on eBait? See,
e.g. here:
I had those on my watch-list and just shake my head at the astonishing
prices for the things.
I've wondered if you might not make DECtape tape from 3/4" video tape.
I know that DECtape has mylar on both sides but what if you somehow
glued two strips of video tape together with the mylar backing on the
outside. Probably want to build a jig of some sort and I'm not sure
what glue to use.
10:54 a.m.
On Jan 13, 2018, at 08:52, Bill Gunshannon via cctalk
<cctalk at classiccmp.org> wrote:
So, where were all these people when I was trying to clean out
my old house a couple years ago? I threw out piles of tapes of
various formats because I couldn't find anyone to take them for
postage.
I'm sorry that I missed that event, Bill! I'd be happy to add a DECtape drive and
a handful of usable DECtapes to my PDP-8/M project, but I don't want that dearly
enough to pay the going eBay prices for that kind of gear at this time. Not that I can
really complain, as I'm fortunate to have lots of other cool stuff running the range
from free gifts to expensive purchases; I just haven't been at the right node of place
+ time + checking account balance to have acquired DECtape family gear yet, and I was born
just a bit too late to have experienced it in college or the workplace.
I sure wish that I would have anticipated that I'd become interested in retrocomputing
in the 201x decade, so I wouldn't have gotten rid of a few specific items over the
years that I now wish I still had, and I could have kept my eyes open for other items that
I might have acquired cheap or free at the moment that interest in them was at a minimum.
Naturally, there's plenty of stuff in recent years that I have considered to be
uninteresting junk to be discarded. I wonder if I'll regret having junked it in
another decade or three, or if my sense of nostalgia will remain rooted to my younger
years and earlier?
9:04 a.m.
On 01/13/2018 08:34 AM, David Bridgham via cctalk wrote:
At Washington University, we bought 12" reels of 3/4"
instrumentation tape and made DECtapes out of them.
The tapes were too thin, and if you left them sit too long,
they would get print-through and start to have trouble.
As long as you used them every couple weeks, they would get
rewound and you would not have a problem.
I don't know what you are talking about with Mylar on both
sides. They were conventional magnetic tape, a clear mylar
film with oxide applied to one side. They were definitely
made with a thicker Mylar layer than many magnetic tapes of
the day, possibly to solve the print-through issue, but
maybe also to prevent crimping of the tape on the pack. I
think the oxide formula had a more square-loop hysteresis
curve than analog tapes, which contributed to our problem.
Jon
So why are
reels of DECtape selling for unbelievable prices on eBait? See,
e.g. here:
I had those on my watch-list and just shake my head at the astonishing
prices for the things.
I've wondered if you might not make DECtape tape from 3/4" video tape.
I know that DECtape has mylar on both sides but what if you somehow
glued two strips of video tape together with the mylar backing on the
outside. Probably want to build a jig of some sort and I'm not sure
what glue to use.
9:28 a.m.
On 1/13/18 9:04 AM, Jon Elson via cctalk wrote:
I don't know what you are talking about with Mylar
on both sides. They were conventional magnetic tape, a clear mylar
film with oxide applied to one side.
the actual spec is here:
http://bitsavers.org/pdf/dec/dectape/3M_DECtape_Spec_Nov66.pdf
10:25 a.m.
On Jan 13, 2018, at 12:28 PM, Al Kossow via cctalk
<cctalk at classiccmp.org> wrote:
On 1/13/18 9:04 AM, Jon Elson via cctalk wrote:
And that spec is quite clear, "protective overlay". This is the reason for the
legendary robustness of DECtape media. It was possible to wear it out, but only if you
used it -- as done at Lawrence University for example -- as permanently mounted public
file storage so it was read/written many times per hour for months on end. When used as
private removable storage it was pretty much invulnerable. Stories of DECtapes being
laundered by accident and still working fine afterwards have been around for a long time.
paul
I don't know what you are talking about with
Mylar on both sides. They were conventional magnetic tape, a clear mylar
film with oxide applied to one side.
the actual spec is here:
http://bitsavers.org/pdf/dec/dectape/3M_DECtape_Spec_Nov66.pdf
4:32 p.m.
On 01/13/2018 11:28 AM, Al Kossow via cctalk wrote:
On 1/13/18 9:04 AM, Jon Elson via cctalk wrote:
Ah, looks like a 40 MICRO-Inch protective coating.
Certainly not a couple mils of Mylar on both sides of the Oxide.
Jon
I don't know what you are talking about with
Mylar on both sides. They were conventional magnetic tape, a clear mylar
film with oxide applied to one side.
the actual spec is here:
http://bitsavers.org/pdf/dec/dectape/3M_DECtape_Spec_Nov66.pdf
16 Jan
16 Jan
10:04 a.m.
On Sat, Jan 13, 2018 at 7:34 AM, David Bridgham via cctalk <
cctalk at classiccmp.org> wrote:
I've wondered if you might not make DECtape tape
from 3/4" video tape.
I know that DECtape has mylar on both sides but what if you somehow
glued two strips of video tape together with the mylar backing on the
outside. Probably want to build a jig of some sort and I'm not sure
what glue to use.
I have read on several occasions about the mylar on both faces of the
tape. I have over 300 reels of DECTape in my collection. Most of these
are 3M Scotch branded but around 30 of them are DEC branded in the blue
plastic boxes. I have never seen one with mylar on both sides. This may
have been something that existed early on but certainly wasn't the norm.
--
Doug Ingraham
PDP-8 SN 1175
10:19 a.m.
On Jan 16, 2018, at 1:04 PM, Doug Ingraham via cctalk
<cctalk at classiccmp.org> wrote:
On Sat, Jan 13, 2018 at 7:34 AM, David Bridgham via cctalk <
cctalk at classiccmp.org> wrote:
Well, the spec is clear about a protective layer on top. And I've always been told
that it's mylar. And the fact that DECtape is far more wear resistant than regular
magtape makes it clear it isn't constructed the same way.
It is correct that it doesn't have a glossy top layer matching the glossy substrate.
But that doesn't mean there isn't a top layer present.
paul
I've wondered if you might not make DECtape
tape from 3/4" video tape.
I know that DECtape has mylar on both sides but what if you somehow
glued two strips of video tape together with the mylar backing on the
outside. Probably want to build a jig of some sort and I'm not sure
what glue to use.
I have read on several occasions about the mylar on both faces of the
tape. I have over 300 reels of DECTape in my collection. Most of these
are 3M Scotch branded but around 30 of them are DEC branded in the blue
plastic boxes. I have never seen one with mylar on both sides. This may
have been something that existed early on but certainly wasn't the norm. 
13 Jan
13 Jan
12:43 p.m.
On 1/13/2018 6:20 AM, Noel Chiappa via cctalk wrote:
So why are reels of DECtape selling for unbelievable
prices on eBait?
The ones in the post are from Bill Donzelli.? I'd imagine
he's happy.? I
looked at acquiring another one, but they went way high as you pointed
out.? My friend with some of the TU-55 and TU-56's has several boxes and
said not to bother, but I figured what the heck.
Bill didn't sell the 4 piece one.? I bought a single item last year for
$5 bucks or so plus shipping.? I'm not sure why these have gone so high.
We are talking to a local fellow here in Los Angeles who is in the
business of renting out a studio with ancient tape drives for production
as needed and he has contact with a couple of guys who may be able to
fab up heads.? We are interested in exploring that if it is feasible to
have replacements made.? They currently make heads for the audio units
there and could possibly make heads to any spec that is available.
I'm mainly asking around because it seems there are a lot of options for
moving tape now days.? Media is scarce, but not unavailable. And unless
you have NOS replacement heads that is one stopper for using original
media with system.? I probably won't pursue it, but will at least know
how hard the head problem is.
Thanks
Jim
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10 comments
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aek＠bitsavers.org -
bill.gunshannon＠hotmail.com -
dab＠froghouse.org -
dpi＠dustyoldcomputers.com -
elson＠pico-systems.com -
jnc＠mercury.lcs.mit.edu -
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paulkoning＠comcast.net