A teleprinter (teletypewriter, Teletype or TTY) is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the transmission medium. They could also serve as a command line interface to early mainframe computers and minicomputers, sending typed data to the computer with or without printed output, and printing the response from the computer.
The teleprinter evolved through a series of inventions by a number of engineers, including Royal Earl House, David E. Hughes, Edward Kleinschmidt, Charles Krum, Emile Baudot and Frederick G. Creed.
Later versions of the model 7 were introduced to provide the additional facilities that were required by the Telex network, or to improve the performance of the basic machine. The first variant was the model 7D, which incorporated a relay to signal to the controlling equipment when the driving motor had reached its governed speed. The next version, the model 7E, incorporated a completely re-designed receiving cam shaft assembly, known as the overlap cam unit. With all earlier versions of the model 7, the received character was not actually printed until the next character was received. This was due to the limited time available with the 6½ unit receiving cycle. The overlap cam unit overcame this limitation by means of three sequentially operated cam shafts. The first cam shaft included an "Orientation device” (some times called a "Range Finder”) which allowed the sampling periods of the receive mechanism to be optimised to the incoming signal. The second cam shaft carried out the received character sampling and processing as before, and the final cam shaft caused the printing to be carried out whether or not another character was being received.
The model 7 was finally introduced in 1931.
Our model 7E with a serial number of 93897 was very kindly donated by Bill Williams good friend Malcolm Batchelor.
Date : 1968
Manufacturer : Creed
This exhibit has a reference ID of CH16730. Please quote this reference ID in any communication with the Centre for Computing History.
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