Hello seattle,
Thanks for the question - and the memories. I actually had one of
these Teletype machines at work in the early 70's. I recall them to be
slow, unreliable, and expensive!
Columbia University has a good online museum with pictures of some
models at http://www.columbia.edu/acis/history/teletype.html .
They mention:
"Teletype machines from the Teletype Corporation, Skokie, Illinois.
Left: The Teletype Corporation ASR 33 Teletype (1967). 110 bps,
8-level ASCII encoding (uppercase only); 4-row Automatic Send Receive,
101C Dataset (modem); Bell System TWX service. Right: ASR33 without
built-in telephone: 100% mechanical, no electronics. Regular
maintenance and lubrication is required. "
"Pushing the keys was a good exercise; the keys traveled a good half
inch before making contact, and resistance was considerable. The
Answerback reply was programmed by breaking teeth off a plastic gear.
Teletypes in one form or another go back to about 1909. They were used
originally as automatic Telegraph and Telegram machines. Teletypes
reached their familiar mature form around 1920"
The page links to a History of the Teletype at
http://www.rtty.com/history/nelson.htm
HISTORY OF TELETYPEWRITER DEVELOPMENT
R. A. Nelson
K. M. Lovitt, Editor
October 1963
Teletype Corporation
5555 West Touhy Avenue
Skokie, Illinois
His story begins:
"Area I. In 1902 a young electrical engineer named Frank Pearne
solicited financial support from Joy Morton, head of the Morton Salt
interests. Pearne had been experimenting with a printing telegraph
system and needed sponsorship to continue his work. Morton discussed
the matter with his friend, Charles L. Krum, a distinguished
mechanical engineer and vice president of the Western Cold Storage
Company (which was operated by Joy's brother, Mark Morton). The
verdict for Pearne was favorable, and he was given laboratory space in
the attic of the Western Cold Storage Company.
After about a year of unsuccessful experimenting, Pearne lost
interest and decided to enter the teaching field. Charles Krum
continued the work and by 1906 had developed a promising model. In
that year his son, Howard, a newly graduated electrical engineer,
plunged into the work alongside his father. The fruit of these early
efforts was a typebar page printer (Patent No. 888,335; filed August
22, 1903; issued May 19, 1908) and a typewheel printing telegraph
machine (Patent No. 862,402; filed August 6, 1904; issued August 6,
1907). Neither of these machines used a permutation code.
They experimented with transmitters as well, applications filed in
1904 and 1906 maturing into Patents No. 929,602 and No. 929,603.
These patents covered modes of transmission which depended both on
alternation of polarity and change in current level.
By 1908 the Krums were able to test an experimental printer on an
actual telegraph line. The typing portion of this machine was a
modified Oliver typewriter mounted on a desk with the necessary
relays, contacts, magnets, and interconnecting wires (Patent No.
1,137,146; filed February 4, 1909; issued April 27, 1915). As a result
of the successful test of this printer, Charles and Howard Krum
continued their experiments with a view to developing a direct
keyboard typewheel printer. "
Interesting roots! You will probably enjoy reading the entire report.
TeleType terminals were also used as the "front end" in early computer
development. http://cm.bell-labs.com/cm/cs/who/dmr/picture.html shows
them being used to input into PDP-11's.
Further searching uncovered another example of the same 1963 paper
above, but more complete at
http://www.thocp.net/hardware/history_of_teletype_development_.htm
Additional information here addresses your question on TeleType use
today and includes:
AT & T Telegraph Service
BASKING RIDGE, N.J. -- Familiar to the world over through the
clickety-clack of ticker tape machines and teletypewriters, telegraphy
has been gradually bowing out of the telecommunications picture during
the last twenty years.
The nonstop chatter has been replaced by the hum of laser printers and
the electronic beeps on computer screens. AT&T, a leading innovator
and major service provider of telegraphy, announced this year it is
withdrawing the service due to the universal availability of
lower-cost, higher quality digital telecommunications services.
"The incredible advances in our industry means customers can get more
for less," said Wes Bartlett, AT&T district manager, Business
Communications Services. "Today's digital technology can transmit
information hundreds of thousands times faster than telegraphy and is
considerably more cost-effective for users.
"Telegraphy has been to the twentieth century what state-of-the-art
digital telecommunications services will be to the next century,"
Bartlett added. "We are proud of our contributions in both areas."
The transmission of telegraph service is based on analog technology,
which sends information by continuous electrical waves. Today's
digital technology breaks information into its smallest components,
the binary "ones and zeros" of computer language.
However, telegraphy was the actually the first digital service --
although a very simplified version compared with today's technology --
since it was produced on the customer's premises in terms of "on or
off," or "dash or space." It was converted to analog for transmission.
Most of AT&T's telegraph service customers have been converted to
digital private line services such as DATAPHONE (R) Digital Service
and ACCUNET (R) Spectrum of Digital Services.
"Our name remains American Telephone and Telegraph," Bartlett said.
"It is an historic name and our legacy. We are proud to have a
corporate name that spans generations of communications technology.
"Despite rapid technological change, AT&T remains focused on helping
people communicate," Bartlett added. "Telegraphy helped bring us to
this point. Digital technology is taking us into a new era of global
messaging."
A few interesting facts will be found as the articles and reports
progress:
Here's how it worked:
Customer A sent information to customer B by typing the information on
a teletypewriter keyboard. The teletypewriter converted the message to
a coded signal which was sent out on the local loop to the STC and
central office equipment. There the signal was converted to make it
compatible with the carrier's lines and sent on to the STC serving the
distant city. The central office equipment then converted the signal
again and sent it over the local loop to customer B's teletypewriter
which decoded the signal and printed the information.
The procedure was reversed if customer B wanted to send information to
customer A. This method of sending information, where only one station
could send at a time, was accomplished over a simple half-duplex, or
two-wire circuit. When both customers wanted to send and receive at
the same time a full-duplex, or four-wire circuit, was used.
At its peak in 1970, telegraph service could transmit data at 150 bits
per second.
1887: First private-line telegraph service, for L. H. Taylor & Co.,
brokers, between their offices in New York and Philadelphia.
1888: First service for news media customer, Globe Newspaper Company,
between New York and Boston.
1915: Teletype offers speeds of 30 or 50 words per minute.
1920s: Press and financial markets create a boom for usage of the
service.
1939: Speed reaches 75 words per minute.
1944: Speed reaches 100 words per minute.
1957: Teleprinter introduces speeds of 300 words per minute.
1970s: Decline in usage begins as electronic data processing replaces
many telegraph functions.
1980s: Wireless and digital methods accelerate decline.
1991: AT&T exits telegraph service.
There is a great deal more history on these pages.
Thanks for the interesting question to research. My search strategy
was simple "teletype" and a short scan of my memory banks. If anything
above is unclear, please do ask for clarification.
Regards,
-=clouseau=- |
