> On Jan 23, 2022, at 8:40 PM, Noel Chiappa via cctalk
> wrote:
>
>> From: Gary Oliver
>
>> I've always thought the physical tape wound on a DECtape spool was a
>> fairly conventional 'sandwich' of mylar/oxide/mylar ...
>> Was there some kind of 'lubricating' coat on the data side? It makes
One way to tell is to do an independent test. I have a ton of Dectape,
including some stuff that is probably psychological data from 50 years ago.
So what are the exact steps, I'll replicate on some LincTapes and report
back.
C
On 1/24/2022 10:30 AM, Paul Koning via cctalk wrote:
On Jan
Back in 1971 or so, we had a PDP-5 with DECTapes, and bought
3/4" analog recorder tapes surplus to make up new tapes. It
was much thinner than DECTape, and we had print-through
issues of tapes that were stored for a few weeks. That
seemed to clear up if the tapes were then used again. I
gues
> On Jan 24, 2022, at 10:56 AM, Jon Elson via cctalk
> wrote:
>
> Back in 1971 or so, we had a PDP-5 with DECTapes, and bought 3/4" analog
> recorder tapes surplus to make up new tapes. It was much thinner than
> DECTape, and we had print-through issues of tapes that were stored for a few
On 1/24/22 7:30 AM, Paul Koning via cctalk wrote:
On Jan 23, 2022, at 8:40 PM, Noel Chiappa via cctalk
wrote:
From: Gary Oliver
I've always thought the physical tape wound on a DECtape spool was a
fairly conventional 'sandwich' of mylar/oxide/mylar ...
Was there some kind of 'lubricating' coa
> On Jan 23, 2022, at 8:40 PM, Noel Chiappa via cctalk
> wrote:
>
>> From: Gary Oliver
>> I've always thought the physical tape wound on a DECtape spool was a
>> fairly conventional 'sandwich' of mylar/oxide/mylar ...
>> Was there some kind of 'lubricating' coat on the data side? It makes
>>
It sounds more like some sort of sprayed-on coating of some sort of
abrasion-resistent material. It might well be porous, which would be a
possible explanation for the oxide coming off when rubbed with solvent.
paul
Is it possible we're looking at something called "dirt"?
C
The other thing on my mind is, high end audio tape from the same period had a
coating to reduce static electricity. But that would be on the rear side.
> On 24 Jan 2022, at 20:09, Chris Zach via cctalk wrote:
>
> It sounds more like some sort of sprayed-on coating of some sort of
> abrasion-re
On 1/24/22 11:05, Paul Koning via cctalk wrote:
> Looking at that spec some items pop out.
>
> The coating is quite thin, much thinner than the backing. Not too surprising
> actually, if it were thick it would reduce the max possible bit density.
>
> There is a coating wear spec (as a ratio of
> On Jan 24, 2022, at 2:46 PM, Chuck Guzis via cctalk
> wrote:
>
> On 1/24/22 11:05, Paul Koning via cctalk wrote:
>
>> Looking at that spec some items pop out.
>>
>> The coating is quite thin, much thinner than the backing. Not too
>> surprising actually, if it were thick it would reduce
> From: Gary Oliver
> Paul - thanks for the bitsavers reference.
Ahem!
In any case, it's Al who really deserves the credit, for finding that document,
and
putting it up.
Noel
On 1/24/22 11:50, Paul Koning wrote:
>
> I thought Black Watch has coating on the back, as others mentioned. DECtape
> is not black but brown, so graphite doesn't seem to be involved.
I grabbed a reel of BW out of my stash and you're correct--the black is
on the back.
Still, I can see where a
On 1/24/22 11:09 AM, Chris Zach via cctalk wrote:
It sounds more like some sort of sprayed-on coating of some sort of
abrasion-resistent material. It might well be porous, which would be
a possible explanation for the oxide coming off when rubbed with solvent.
paul
Is it possible we're
On 1/24/22 12:42 PM, Noel Chiappa via cctalk wrote:
> From: Gary Oliver
> Paul - thanks for the bitsavers reference.
Ahem!
In any case, it's Al who really deserves the credit, for finding that document,
and
putting it up.
Noel
Clearly Al is to blame :-) Yes, thanks to al
FYI, that "unpopulated board" is not and never was S100, and has clearly
had some told contact fingers cut off. Perhaps used as a source for
parts at some point.
You might want to join and post this to the "s100computers" Google group.
JRJ
On 1/23/2022 1:42 PM, Stan Sieler via cctalk wrote:
On 2022-01-23 12:47 p.m., Chuck Guzis via cctalk wrote:
On 1/23/22 10:16, Paul Koning via cctalk wrote:
Maybe. But OCR programs have had learning features for decades. I've spent quite a lot of time in
FineReader learning mode. Material produced on a moderate-quality typewriter, like the C
> On Jan 24, 2022, at 5:57 PM, ben via cctalk wrote:
>
>> ...
> Document source is also a problem.
> You would want to keep scan it at the best data format,
> not something in a lossey format.
That's true generally. Anything other than actual photographs (continuous tone
images) should NOT
> That's true generally. Anything other than actual photographs
> (continuous tone images) should NOT be run through JPEG because JPEG
> is not intended for, and unfit for, anything else. Printouts, line
> drawings, and anything else with crisp edges between dark and light
> will be messed u
I've tried to OCR old Fortran Code from DTIC pdf documents. There were
2 big problems;
1. The copies are very poor to start with and all OCR attempts produced
about 75% error rate.
2. Old Fortran code limited variable names to 6 characters so they were
generally not descriptive of what they r
So, can we assume that the words about a "tape sandwich" refer to a
mylar base, oxide coating, and a lubricant/protective coating?
That is not an oxide coating sandwiched between to layers of mylar.
There was such a tape construction, used on the Datamatic 1000. (ca. 1955)
--Chuck
On Sun, Jan 23, 2022 at 03:09:53PM -0800, Gary Oliver wrote:
> Taking the bits of tape, I exposed them to various concentrations of
> isopropanol/water (from about 25% to 99% iso) and found than in all cases,
> some of the data side of the tape came off on the wipe.? The remaining tape
> fragment
On 1/24/22 4:25 PM, David Gesswein via cctech wrote:
On Sun, Jan 23, 2022 at 03:09:53PM -0800, Gary Oliver wrote:
Taking the bits of tape, I exposed them to various concentrations of
isopropanol/water (from about 25% to 99% iso) and found than in all cases,
some of the data side of the tape cam
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