110 Baud modem

[Pete Lancashire]

The BSPs for Data Set 101C

Identification and Operation March 1963 (Issue 2)

Test and Installation Methods May 1967

Locating Trouble and Test Procedures 1964

http://www.samhallas.co.uk/repository/telegraph/data_set_101c.pdf

Answers the questions about the relays

-pete



On Tue, May 9, 2017 at 7:57 AM, Pete Lancashire <pete at petelancashire.com>
wrote:

> Wikipedia is wrong a lot of times. Usually in the details.
>
> Modem or MOdulator DEModulator had to come about when one could finally
> put a modulator (voltage or current loop) in and get a modulated signal
> out, and the reverse, and thirdly all the control circuitry to automate
> things.
>
> Long before that, each function was separate.
>
> I can find 1958 and SAGE but non have any proof, and many references are
> circular.
>
> On Tue, May 9, 2017 at 7:39 AM, Paul Koning <paulkoning at comcast.net>
> wrote:
>
>> So Wikipedia is wrong, since it claims that it was introduced in 1958 for
>> ASCII and 110 Baud.
>>
>> Then again, 101/103 modem modulation doesn't care about speed (it isn't
>> clocked) up to a limit of 300 baud or so.
>>
>> I wonder if there is also terminology here: what we now call a "modem"
>> was earlier called a "tuning unit" and that term goes back to 5 bit
>> machines and the 1950s.  It may be more a radio TTY term than a landline
>> term, but the concept is identical.  I remember QST articles around 1958 or
>> so about RTTY tuning units, built out of tubes with a relay (differential
>> relay?) thrown in for good measure.
>>
>>         paul
>>
>> > On May 9, 2017, at 10:32 AM, Pete Lancashire <pete at petelancashire.com>
>> wrote:
>> >
>> > The C version came later with the introduction of ASCII ( 5 to 8 bits )
>> and 110 baud. So it does not go back to the 50's.
>> >
>> > I do not know when the C version was released. The ASCII Teletype Model
>> 35 was introduced in 1961.
>> >
>> > -pete
>> >
>> >
>> >
>> >
>> > On Tue, May 9, 2017 at 6:47 AM, Paul Koning <paulkoning at comcast.net>
>> wrote:
>> >
>> > > On May 8, 2017, at 10:27 PM, Pete Lancashire via cctalk <
>> cctalk at classiccmp.org> wrote:
>> > >
>> > > Bell 101C
>> > >
>> > > https://goo.gl/photos/hrhAwvzMBLWWteXu6
>> > >
>> > > https://en.wikipedia.org/wiki/Bell_101
>> >
>> > Interesting.  Released in 1958 but that unit is stamped 10 years later.
>> >
>> > It would be nice to see photos of the circuit boards.  And I sure
>> wonder what those rows of large relays are for.
>> >
>> >         paul
>> >
>> >
>> >
>> >
>>
>>
>>
>