The Teletype machines from the Teletype Corporation, Skokie, Illinois, were
ubiquitous at non-IBM computing installations in the 1960s and 70s.
Notably, they were often supplied with minicomputers such as the Digital
Equipment Corporation PDP-11/20, for example (at the lab where I worked at
Mt. Sinai Hospital in NYC in the early 1970s). Left: An ASR33
without built-in telephone. Right: 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. Teletypes were
nearly 100% mechanical with no electronics to speak of and required regular
maintenance and lubrication.
The ASR33 was by far the most common Teletype model in the mid-to-late
1960s, although we did have an ASR37 in the machine
room for some time. But as to the model 33... The paper is roll-fed.
The paper tape device was be used for sending recorded keysrokes or other
data, or to capture incoming material (thus Automatic Send Receive). The
KSR models (Keyboard Send Receive) lacked the paper tape reader/punch. Most
non-IBM computers of the 1960s until the mid-1970s — such as DEC
PDP-xx minicomputers — came with a Teletype console terminal. The 33
and 35 models were uppercase only; the 37 model had upper and lower case.
To this day certain characteristics of the Telepype live on in the
110-"baud" 2-stop-bits configuration required to synchronize with the
Teletype printing mechanism, still supported by most modems, serial ports,
Pushing the keys was 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 1907. They were used originally as automatic
Telegraph and Telegram machines. Teletypes reached their familiar mature form
in the 1920s and the ASR33 was announced 1962.
In addition to sending and receiving text, Teletypes could also be used to
transcribe text from keyboard to paper tape for storage and eventual re-use,
and also to create line-printer carriage-control tape loops for printers
such as the IBM 1403. In this case
heavy-duty Mylar tape was often used instead of paper tape. At Columbia
during the mainframe era, users could have operators "mount" custom
printer control tapes for their jobs (see a story about this