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Posted by Herb Stein on October 31, 2007, 7:45 pm
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>
>>
>>>>
>>>>Now here's a bonus question: Who invented the chadless process? Was it
>>>>the
>>>>Bell System (via Western Electric and Teletype) or was it Klienschmidt
>>>>or
>>>>some other company? (I don't know the answer but I'd like to know!)
>>>>
>>> I don't have a definitive answer, but it must have been Teletype/Bell
>>> System, because Kleinschmidt made typing reperforators that used 7/8"
>>> tape and typed on the edge where there was no punching. The reason
>>> for chadless tape was to provide a surface to print on, with a typing
>>> reperforator.
>>>
>>>
>>> ***** Moderator's Note *****
>>>
>>> That brings back a memory: the Model 19 I learned on had a typing
>>> reperforator, the Model 14 IIRC, which used "chadless" tape and
>>> printed on the chads. It also had a type wheel very much like the one
>>> later used on the Model 32/33. It was very useful for making "Brag"
>>> tapes, which were sometimes played during radio contacts: if you
>>> realized you'd make a mistake in the tape, you could run it through
>>> the reader on the Model 19, up to the point of the mistake, and type a
>>> corretion, and then run the rest: the reperforator would produce a
>>> correct copy.
>>>
>>> The hams at M.I.T. had to wind replacement ribbons themselves, because
>>> the reels used by TeleType cost too much.
>>>
>>> Trivia question: when first establishing contact, the stations would
>>> often send a series of "RY" characters repeatedly. Why?
>>
>> We're going back into the mental archives here. As I recall, that
>> string was as close as you can get to equal numbers of marks and
>> spaces. So whatever the loop current was (maybe 20ma), RYRYRY, etc
>> would cause to current meter to register half of the always-on loop
>> current. I've forgotten the name of that big relay (bi-polar?) that we
>> all got from the old Bell System. If it was out of whack, you would
>> get something more or less than the10ma in my example. Of course, you
>> could do the same thing locally with your model 15 tape distributor.
>>
>> If this is right, do I win a prize? :-)
>>
>> Herb Stein
>> herb@herbstein.com
>>
>>
>> ***** Moderator's Note *****
>>
>> Herb, you're very close. Yes, the sequence "RY" _is_ an alternating
>> stream of Mark/Space signals, i.e., a "101010101010101010101010 ..."
>> pattern.
>>
>> However, it wasn't used to measure current.
>
> I've thought about this all day. And it is the pattern above, but
> you're ignoring the start and stop bits. But it is as close to your
> pattern as is possible. I'm going back to 1961 or so my memory
> fades. I can't remember if I have socks on! I don't remember what it
> measured, but I had a small meter which would be at about half the
> normal reading when the famous RYRY... was sent from the model 14 TD
> on the local loop. I guess I "misremember" what the meter was reading.
>
> I still have the home-brew thing with the polar relay ans associated
> socket, H-88 Bell load coils, etc. I gave away the hardware years ago.
>
> In any event, great flashback!
>
>> Bill Horne
>> Temporary Moderator
>>
>> P.S. The prize is too incredible to mention!
>
> --
> Herb Stein
> herb@herbstein.com
>
>
> ***** Moderator's Note *****
>
> Herb, you're the closest, so you win. You're right: I didn't count the
> start and stop bits.
>
> If you had a current meter in the loop and watched it during an RY
> sequence, I understand how it would show about half scale. I don't
> think that would be a good tuning indicator, though.
>
> In radio, the RY sequence was used to produce a "cross" pattern on a
> monitoring scope, or to guide a discrimator output meter to the
> center.
I never had that kind of fancy hardware, but I can see that working.
> Trivia question #2: what is the equivalent character pattern when
> using a Model 35?
>
> Trivia question #3: what key combination would produce a
> blank tape, with only feed holes punched, on a Model 33ASR?
I never had anything new enough to use the 8-level ASCII tape.
Just the WWII surplus 5-level Baudot stuff. The old stuff was free
from the Military Affiliate Radio System (MARS).
Being 15 in 1961, I had no contacts in the phone company to get
the new stuff from.
> Bill Horne
> Temporary Moderator
--
Herb Stein
herb@herbstein.com
***** Moderator's Note *****
Truth be told, I never had that kind of fancy hardware, either: my
first TU was a two-tube unit that I tuned by watching the copy! I had
a model 15 TeleType, which I'd bought for about $40, from a service
which redistributed them to hams on a "Not For Resale" basis. It had a
pin-feed platten, and so I was always scronging pin-feed paper.
I would still have it today, except that my father put it in the
trash while I was in Vietnam.
My first experience with ASCII was with the PDP-8 "Edusystem" computer
used in local schools, which had a 33 ASR as a terminal. I got a job
maintaining the TeleTypes, and they sent me to North Wacker Drive in
Chicago to learn how.
That was during the time I was laid off from NET&T, so I didn't have
any contact in the phone company, either, but if it's any comfort,
they were still using Model 28's well into the Seventies: the first
contact many of their own repairmen had with ASCII was in fixing the
Model 35's that came with the 1A ESS, and they'd still use "RY" as a
test pattern, even though "U*" was the equivalent ASCII sequence.
Bill Horne
Temporary Moderator
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