110 Baud modem
bhilpert at shaw.ca
Tue May 9 13:49:53 CDT 2017
>> 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
>> 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.
>> 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.
On 2017-May-09, at 7:39 AM, Paul Koning via cctalk 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.
If my recollection and interpretation of the limited tech description available is correct, SIGSALY was doing frequency-domain-multi-channel, FSK-digital-transmission during WWII, that is, sending multiple digital bit streams over a radio channel. (Along with a host of other amazing technical achievements for the time, including or esp. in the digital realm).
I haven't looked into whether RTTY was prior to that, or post-war, or whether RTTY may have got some of the ideas from SIGSALY.
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