Subject: paper tape

From: [email-masked] (Charles Lasner)
Date: 22 Mar 1994 18:54:52 GMT

Here's another small issue from the back pages of the lovers list.

>Date: Fri,  4 Aug 89 19:51:36 EDT
>From: "Robert E. Seastrom" <[email-masked]>
>Subject:  [jmbaldwi: I've got a pdp8 that I'd like to use.]
>To: [email-masked]
>cc: [email-masked], 
>    [email-masked]
>In-reply-to: Msg of Fri  4 Aug 89 19:04:02 EDT from Christopher R. Zach 
<CZ%AI.AI.MIT.EDU at MINTAKA.lcs.mit.edu>

>Re: papertape in boxes...

>Last time I called DECdirect to inquire about this (was about
>2 years ago), they were selling paper tape for $120/case.  I
>think that there are something like 20 boxes in a case - in other
>words, this is not cheap stuff.  If anyone out there knows where
>we can get fan-folded, non-oiled, 1" paper tape for cheaper, I'd
>really like to know about it.  I've been kicking around the idea
>of trying to get tyvek (yes, I know it's hard on the punch) tape
>and putting things like RIM and BIN loaders on it, but I haven't
>had the time to try to track this stuff down.  Keep in mind that
>I have a couple of boxes of 9 rolls each of oiled yellow paper tape
>that we could use...  the only reason not to use oiled paper tape
>in a high speed reader is that the lint from the tape will gunk
>up the photodiodes that actually read the tape...  you can clean
>these off; it is just a pain.

>                   ---Rob

Well, that's not the entire story:

You shouldn't use oiled paper-tape on the high-speed reader because it
won't work!  Most oiled yellow tape is too translucent to use with the
reader which works photo-electrically, not mechanically.  Notice that
oiled tape is usually yellow (and a cheaper grade of paper) while
non-oiled is usually either grey or black (and clearly an opaque piece of
paper).  Fan-fold is preferable, but not absolutely required, although
it's what you have to feed through the DEC punch if you don't want to
resort to external spools, etc.

I've also seen some green paper tape that some readers can/cannot read.
Later vintage PC04/05 readers have an ECO which helps channel the light
source, etc.  I think these newer readers *cannot* read this marginal
stuff!

cjl

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From: [email-masked] (PDP11 Hacker .....)
Date: Tue, 22 Mar 1994 19:28:00 GMT

In article <[email-masked]>, [email-masked] (Charles Lasner) writes...
>reader which works photo-electrically, not mechanically.  Notice that

Now, I've not done much with my PC05 (OK, so it's a PDP11 system, but don't
flame me too much), as I use the English Trend readers. I'm not sure if they
made it across the Pond, but they're actually quite nice. There are 10 (not 9)
photodiodes in the read head - 2 on the sprocket track 2.5 character spaces
apart. The reader electronics uses the signals from these 2 sensors (one is
light, the other dark when a character is being read) to determine a threshold
for the data tracks (and I assume the sprocket track - but the service manual
is not here). They are trivial to set up (put a filter in the light path,
connect a multimeter to some pins on the board, and tweak for 0 voltage), and
simple mechanically (the Unidirectional UDR350 and UDR700 (the numbers are the
speed in chars/sec) have the capstan roller on the end of the motor spindle, a
solenoid-controlled pinch roller under the chassis, and an electromacnetic
break to stop the tape, while the bidirectional HSR500 has 2 capstans with a
belt drive, but is otherwise similar). Yes, they can stop on a character, even
going at full speed.
They are (of course) photoelectric, and I've yet to find a tape they can't
read. I really like them. Oh, and there was a PDP8 interface - the schematic
was in one of the manuals I got with one of my 700's

>I've also seen some green paper tape that some readers can/cannot read. 

I've seen green, red, and blue tape. Never had any trouble with it. Most of my
tapes are white oiled stuff. 

>source, etc.  I think these newer readers *cannot* read this marginal

What does this consit of, so I can find out if it was done to my poor PC05? 

>cjl
-tony

Bristol University takes no responsibility for the views expressed in this
posting. They are the personal views of the user concerned.

---

From: [email-masked] (Charles Lasner)
Date: 23 Mar 1994 07:55:45 GMT

In article <[email-masked]>,

>What does this consit of, so I can find out if it was done to my poor PC05?

The PC04 and PC05 are the same reader.  The difference is in the
interface block which you could transplant.  The -12, -15, and -11 use
the PC05, and all else use the 04.  The 04 is able to be configured to
more machines such as the 8/e, -8, -8/s, -8/i, -8/l, etc.  It's a matter
of "leaning" negative while the 05 is strictly positive, etc.  (Some PC04
configurations are more negative than others; this also allows the
machines where the ptr interface is built into the wrap such as the -8/i
and -8/l, etc.)

The newest 04/05's should have a form of fiber-optics light "funnel" over
the light source that comes down close to the read station.  Without it,
the bulb orientation can be critical as well as the ability to adjust for
reliable reading, etc.  In fact, it becomes hard to *misadjust* when you
have the ECO!

But it also makes the reader pass too much light through translucent
tape, such as oiled yellow or that light-green stuff.  Thus, those tapes
always read back all ones, etc.

cjl

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From: [email-masked] (Douglas W. Jones,201H MLH,3193350740,3193382879)
Date: 23 Mar 1994 15:48:48 GMT

>From article <[email-masked]>,
by [email-masked] (Charles Lasner):
> tape, such as oiled yellow or that light-green stuff.

I have cases and cases of paper tape in storage, oiled black fanfold tape,
rolls of black unoiled tape, and perhaps some unoiled black fanfold.

If the only problem with oiled tape is translucency in a photoelectric
reader, my stocks of oiled black tape should pose no problems.  Are there
problems with oil other than translucency?  That is, when the manual says
DO NOT USE OILED TAPE, are they afraid of the oil eating the plastic or
something?

Also, for commonly used tapes such as the BIN loader, the traditional
material was mylar.  I have the tag end of a spool of aluminized mylar
tape that could be used to punch such things, but I don't know what
punches are able to handle it (and I don't have any working punch of my
own).
					Doug Jones
					[email-masked]

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From: [email-masked] (PDP11 Hacker .....)
Date: Wed, 23 Mar 1994 22:11:00 GMT

In article <[email-masked]>, [email-masked] (Charles Lasner) writes...
>reliable reading, etc.  In fact, it becomes hard to *misadjust* when you 

OK, so I think mine is the other one - there's a tubular (festoon ?) bulb with
one end cap located in the reader panel, the other in an insulated spring clip.
Below the bulb there's a plastic cylinder parallel to the bulb, to focus the
light on the tape.

>always read back all ones, etc.

Well, on my reader there's a resistor in series with the bulb, just inside the
front panel. It consists of a wirewound resistor with an adustable clip on it,
so that you can vary the resistance. It's currently set to minimum. Would
increasing that resistor (so dimming the lamp) help on ECO'd readers?

-tony

---

From: [email-masked] (Charles Lasner)
Date: 24 Mar 1994 01:04:34 GMT

In article <[email-masked]>,
>Below the bulb there's a plastic cylinder parallel to the bulb, to focus the

That's definitely the old one.  You have to tinker with the focus to get
it to work.  It can be quite finicky, etc.

>increasing that resistor (so dimming the lamp) help on ECO'd readers?

I think minimum setting is too much even on the old reader!  You are
sacrificing bulb life for adjustment slop, etc.  Considering the
difficulty in getting another bulb, I would set it down regardless, etc.
before you burn it out!

On ECO'd readers, the bulb can be dimmed even more, since more of the
light gets efficiently to the read station just where it's needed.  I
don't think the adjusting down is mandatory, just recommended in that
case though.

It's conceivable that the translucent tape can be read if the light level
is trickily adjusted, but for best overall results, you want to favor the
more common opaque variety, etc.

cjl

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From: [email-masked] (PDP11 Hacker .....)
Date: Thu, 24 Mar 1994 09:39:00 GMT

In article <[email-masked]>, [email-masked] (Charles Lasner) writes...
>it to work.  It can be quite finicky, etc.

OK. I read the description in the service manual, and it didn't seem _too_ bad.
You needed a 'scope I think for some of the adjustments, but otherwise it seems
OK. Is it really that touchy. It didn't seem to be after I reassembled my
reader, but then again, I don't use it that much, so an intermittant read error
would probably be undetected.

[Lamp resistor]

>difficulty in getting another bulb, I would set it down regardless, etc. 

Right. I _think_ it's at minimum - it's certainly at one end, and I guess
maximum resistance would read nothing. Is the bulb that hard to obtain? I can;t
remember the rating, but I'm sure I found a supplier of them. That's another
area where my favourite Trend readers score. The bulbs are standard car bulbs
(12V 21W in the UDRs/self powered HSR, 24V 24W in the separately powered
HSR/puch/reader station. The 12V bulbs are available from _any_ car shop over
here, and the 24V ones are a standard lorry bulb.) 

>don't think the adjusting down is mandatory, just recommended in that 

If it would work, then I'm sure it would majorly increase lamp life. 

>more common opaque variety, etc.

Not for day-to-day use, but if someone gives you an unreadable tape, then it
might be nice to adjust the reader to be able to copy it.

-tony

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From: [email-masked] (Jim Cook)
Date: 25 Mar 94 16:36:58 GMT

In article <[email-masked]>, [email-masked] (Charles Lasner) writes:
> ... I've been kicking around the idea
> >had the time to try to track this stuff down.  

Don't use tyvek.  It stretches and it deteriorates over time from
ultraviolet light (the latter has become an issue for duPont in
the housing industry).

Many years ago, I saw some mylar stuff.  Silver on one side and I
don't know what (green?) on the other.  It worked with teletypes.
No idea where it came from.

Jim

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From: [email-masked] (John Wilson)
Date: 27 Mar 1994 22:22:00 GMT

Inmac used to sell the mylar stuff.  They had quite a fine paper tape
section in the catalog, back when there was a market for it.  I never
felt the need to order any, my 8/E came with 11.9 miles of DEC paper tape!

John